---
_id: '13974'
abstract:
- lang: eng
text: The Tverberg theorem is one of the cornerstones of discrete geometry. It states
that, given a set X of at least (d+1)(r−1)+1 points in Rd, one can find a partition
X=X1∪⋯∪Xr of X, such that the convex hulls of the Xi, i=1,…,r, all share a common
point. In this paper, we prove a trengthening of this theorem that guarantees
a partition which, in addition to the above, has the property that the boundaries
of full-dimensional convex hulls have pairwise nonempty intersections. Possible
generalizations and algorithmic aspects are also discussed. As a concrete application,
we show that any n points in the plane in general position span ⌊n/3⌋ vertex-disjoint
triangles that are pairwise crossing, meaning that their boundaries have pairwise
nonempty intersections; this number is clearly best possible. A previous result
of Álvarez-Rebollar et al. guarantees ⌊n/6⌋pairwise crossing triangles. Our result
generalizes to a result about simplices in Rd, d≥2.
acknowledgement: "Part of the research leading to this paper was done during the 16th
Gremo Workshop on Open Problems (GWOP), Waltensburg, Switzerland, June 12–16, 2018.
We thank Patrick Schnider for suggesting the problem, and Stefan Felsner, Malte
Milatz, and Emo Welzl for fruitful discussions during the workshop. We also thank
Stefan Felsner and Manfred Scheucher for finding, communicating the example from
Sect. 3.3, and the kind permission to include their visualization of the point set.
We thank Dömötör Pálvölgyi, the SoCG reviewers, and DCG reviewers for various helpful
comments.\r\nR. Fulek gratefully acknowledges support from Austrian Science Fund
(FWF), Project M2281-N35. A. Kupavskii was supported by the Advanced Postdoc.Mobility
Grant no. P300P2_177839 of the Swiss National Science Foundation. Research by P.
Valtr was supported by the Grant no. 18-19158 S of the Czech Science Foundation
(GAČR)."
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Radoslav
full_name: Fulek, Radoslav
id: 39F3FFE4-F248-11E8-B48F-1D18A9856A87
last_name: Fulek
orcid: 0000-0001-8485-1774
- first_name: Bernd
full_name: Gärtner, Bernd
last_name: Gärtner
- first_name: Andrey
full_name: Kupavskii, Andrey
last_name: Kupavskii
- first_name: Pavel
full_name: Valtr, Pavel
last_name: Valtr
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Fulek R, Gärtner B, Kupavskii A, Valtr P, Wagner U. The crossing Tverberg theorem.
Discrete and Computational Geometry. 2023. doi:10.1007/s00454-023-00532-x
apa: Fulek, R., Gärtner, B., Kupavskii, A., Valtr, P., & Wagner, U. (2023).
The crossing Tverberg theorem. Discrete and Computational Geometry. Springer
Nature. https://doi.org/10.1007/s00454-023-00532-x
chicago: Fulek, Radoslav, Bernd Gärtner, Andrey Kupavskii, Pavel Valtr, and Uli
Wagner. “The Crossing Tverberg Theorem.” Discrete and Computational Geometry.
Springer Nature, 2023. https://doi.org/10.1007/s00454-023-00532-x.
ieee: R. Fulek, B. Gärtner, A. Kupavskii, P. Valtr, and U. Wagner, “The crossing
Tverberg theorem,” Discrete and Computational Geometry. Springer Nature,
2023.
ista: Fulek R, Gärtner B, Kupavskii A, Valtr P, Wagner U. 2023. The crossing Tverberg
theorem. Discrete and Computational Geometry.
mla: Fulek, Radoslav, et al. “The Crossing Tverberg Theorem.” Discrete and Computational
Geometry, Springer Nature, 2023, doi:10.1007/s00454-023-00532-x.
short: R. Fulek, B. Gärtner, A. Kupavskii, P. Valtr, U. Wagner, Discrete and Computational
Geometry (2023).
date_created: 2023-08-06T22:01:12Z
date_published: 2023-07-27T00:00:00Z
date_updated: 2023-12-13T12:03:35Z
day: '27'
department:
- _id: UlWa
doi: 10.1007/s00454-023-00532-x
external_id:
arxiv:
- '1812.04911'
isi:
- '001038546500001'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.1812.04911
month: '07'
oa: 1
oa_version: Preprint
project:
- _id: 261FA626-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: M02281
name: Eliminating intersections in drawings of graphs
publication: Discrete and Computational Geometry
publication_identifier:
eissn:
- 1432-0444
issn:
- 0179-5376
publication_status: epub_ahead
publisher: Springer Nature
quality_controlled: '1'
related_material:
record:
- id: '6647'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: The crossing Tverberg theorem
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2023'
...
---
_id: '14445'
abstract:
- lang: eng
text: "We prove the following quantitative Borsuk–Ulam-type result (an equivariant
analogue of Gromov’s Topological Overlap Theorem): Let X be a free ℤ/2-complex
of dimension d with coboundary expansion at least ηk in dimension 0 ≤ k < d. Then
for every equivariant map F: X →ℤ/2 ℝd, the fraction of d-simplices σ of X with
0 ∈ F (σ) is at least 2−d Π d−1k=0ηk.\r\n\r\nAs an application, we show that for
every sufficiently thick d-dimensional spherical building Y and every map f: Y
→ ℝ2d, we have f(σ) ∩ f(τ) ≠ ∅ for a constant fraction μd > 0 of pairs {σ, τ}
of d-simplices of Y. In particular, such complexes are non-embeddable into ℝ2d,
which proves a conjecture of Tancer and Vorwerk for sufficiently thick spherical
buildings.\r\n\r\nWe complement these results by upper bounds on the coboundary
expansion of two families of simplicial complexes; this indicates some limitations
to the bounds one can obtain by straighforward applications of the quantitative
Borsuk–Ulam theorem. Specifically, we prove\r\n\r\n• an upper bound of (d + 1)/2d
on the normalized (d − 1)-th coboundary expansion constant of complete (d + 1)-partite
d-dimensional complexes (under a mild divisibility assumption on the sizes of
the parts); and\r\n\r\n• an upper bound of (d + 1)/2d + ε on the normalized (d
− 1)-th coboundary expansion of the d-dimensional spherical building associated
with GLd+2(Fq) for any ε > 0 and sufficiently large q. This disproves, in a rather
strong sense, a conjecture of Lubotzky, Meshulam and Mozes."
article_processing_charge: Yes (via OA deal)
article_type: original
author:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Pascal
full_name: Wild, Pascal
id: 4C20D868-F248-11E8-B48F-1D18A9856A87
last_name: Wild
citation:
ama: Wagner U, Wild P. Coboundary expansion, equivariant overlap, and crossing numbers
of simplicial complexes. Israel Journal of Mathematics. 2023;256(2):675-717.
doi:10.1007/s11856-023-2521-9
apa: Wagner, U., & Wild, P. (2023). Coboundary expansion, equivariant overlap,
and crossing numbers of simplicial complexes. Israel Journal of Mathematics.
Springer Nature. https://doi.org/10.1007/s11856-023-2521-9
chicago: Wagner, Uli, and Pascal Wild. “Coboundary Expansion, Equivariant Overlap,
and Crossing Numbers of Simplicial Complexes.” Israel Journal of Mathematics.
Springer Nature, 2023. https://doi.org/10.1007/s11856-023-2521-9.
ieee: U. Wagner and P. Wild, “Coboundary expansion, equivariant overlap, and crossing
numbers of simplicial complexes,” Israel Journal of Mathematics, vol. 256,
no. 2. Springer Nature, pp. 675–717, 2023.
ista: Wagner U, Wild P. 2023. Coboundary expansion, equivariant overlap, and crossing
numbers of simplicial complexes. Israel Journal of Mathematics. 256(2), 675–717.
mla: Wagner, Uli, and Pascal Wild. “Coboundary Expansion, Equivariant Overlap, and
Crossing Numbers of Simplicial Complexes.” Israel Journal of Mathematics,
vol. 256, no. 2, Springer Nature, 2023, pp. 675–717, doi:10.1007/s11856-023-2521-9.
short: U. Wagner, P. Wild, Israel Journal of Mathematics 256 (2023) 675–717.
date_created: 2023-10-22T22:01:14Z
date_published: 2023-09-01T00:00:00Z
date_updated: 2023-12-13T13:09:07Z
day: '01'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.1007/s11856-023-2521-9
external_id:
isi:
- '001081646400010'
file:
- access_level: open_access
checksum: fbb05619fe4b650f341cc730425dd9c3
content_type: application/pdf
creator: dernst
date_created: 2023-10-31T11:20:31Z
date_updated: 2023-10-31T11:20:31Z
file_id: '14475'
file_name: 2023_IsraelJourMath_Wagner.pdf
file_size: 623787
relation: main_file
success: 1
file_date_updated: 2023-10-31T11:20:31Z
has_accepted_license: '1'
intvolume: ' 256'
isi: 1
issue: '2'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
month: '09'
oa: 1
oa_version: Published Version
page: 675-717
publication: Israel Journal of Mathematics
publication_identifier:
eissn:
- 1565-8511
issn:
- 0021-2172
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Coboundary expansion, equivariant overlap, and crossing numbers of simplicial
complexes
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 256
year: '2023'
...
---
_id: '10776'
abstract:
- lang: eng
text: 'Let K be a convex body in Rn (i.e., a compact convex set with nonempty interior).
Given a point p in the interior of K, a hyperplane h passing through p is called
barycentric if p is the barycenter of K∩h. In 1961, Grünbaum raised the question
whether, for every K, there exists an interior point p through which there are
at least n+1 distinct barycentric hyperplanes. Two years later, this was seemingly
resolved affirmatively by showing that this is the case if p=p0 is the point of
maximal depth in K. However, while working on a related question, we noticed that
one of the auxiliary claims in the proof is incorrect. Here, we provide a counterexample;
this re-opens Grünbaum’s question. It follows from known results that for n≥2,
there are always at least three distinct barycentric cuts through the point p0∈K
of maximal depth. Using tools related to Morse theory we are able to improve this
bound: four distinct barycentric cuts through p0 are guaranteed if n≥3.'
acknowledgement: The work by Zuzana Patáková has been partially supported by Charles
University Research Center Program No. UNCE/SCI/022, and part of it was done during
her research stay at IST Austria. The work by Martin Tancer is supported by the
GAČR Grant 19-04113Y and by the Charles University Projects PRIMUS/17/SCI/3 and
UNCE/SCI/004.
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Zuzana
full_name: Patakova, Zuzana
id: 48B57058-F248-11E8-B48F-1D18A9856A87
last_name: Patakova
orcid: 0000-0002-3975-1683
- first_name: Martin
full_name: Tancer, Martin
last_name: Tancer
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Patakova Z, Tancer M, Wagner U. Barycentric cuts through a convex body. Discrete
and Computational Geometry. 2022;68:1133-1154. doi:10.1007/s00454-021-00364-7
apa: Patakova, Z., Tancer, M., & Wagner, U. (2022). Barycentric cuts through
a convex body. Discrete and Computational Geometry. Springer Nature. https://doi.org/10.1007/s00454-021-00364-7
chicago: Patakova, Zuzana, Martin Tancer, and Uli Wagner. “Barycentric Cuts through
a Convex Body.” Discrete and Computational Geometry. Springer Nature, 2022.
https://doi.org/10.1007/s00454-021-00364-7.
ieee: Z. Patakova, M. Tancer, and U. Wagner, “Barycentric cuts through a convex
body,” Discrete and Computational Geometry, vol. 68. Springer Nature, pp.
1133–1154, 2022.
ista: Patakova Z, Tancer M, Wagner U. 2022. Barycentric cuts through a convex body.
Discrete and Computational Geometry. 68, 1133–1154.
mla: Patakova, Zuzana, et al. “Barycentric Cuts through a Convex Body.” Discrete
and Computational Geometry, vol. 68, Springer Nature, 2022, pp. 1133–54, doi:10.1007/s00454-021-00364-7.
short: Z. Patakova, M. Tancer, U. Wagner, Discrete and Computational Geometry 68
(2022) 1133–1154.
date_created: 2022-02-20T23:01:35Z
date_published: 2022-12-01T00:00:00Z
date_updated: 2023-08-02T14:38:58Z
day: '01'
department:
- _id: UlWa
doi: 10.1007/s00454-021-00364-7
external_id:
arxiv:
- '2003.13536'
isi:
- '000750681500001'
intvolume: ' 68'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/2003.13536
month: '12'
oa: 1
oa_version: Preprint
page: 1133-1154
publication: Discrete and Computational Geometry
publication_identifier:
eissn:
- 1432-0444
issn:
- 0179-5376
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
scopus_import: '1'
status: public
title: Barycentric cuts through a convex body
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 68
year: '2022'
...
---
_id: '12129'
abstract:
- lang: eng
text: 'Given a finite point set P in general position in the plane, a full triangulation
of P is a maximal straight-line embedded plane graph on P. A partial triangulation
of P is a full triangulation of some subset P′ of P containing all extreme points
in P. A bistellar flip on a partial triangulation either flips an edge (called
edge flip), removes a non-extreme point of degree 3, or adds a point in P∖P′ as
vertex of degree 3. The bistellar flip graph has all partial triangulations as
vertices, and a pair of partial triangulations is adjacent if they can be obtained
from one another by a bistellar flip. The edge flip graph is defined with full
triangulations as vertices, and edge flips determining the adjacencies. Lawson
showed in the early seventies that these graphs are connected. The goal of this
paper is to investigate the structure of these graphs, with emphasis on their
vertex connectivity. For sets P of n points in the plane in general position,
we show that the edge flip graph is ⌈n/2−2⌉-vertex connected, and the bistellar
flip graph is (n−3)-vertex connected; both results are tight. The latter bound
matches the situation for the subfamily of regular triangulations (i.e., partial
triangulations obtained by lifting the points to 3-space and projecting back the
lower convex hull), where (n−3)-vertex connectivity has been known since the late
eighties through the secondary polytope due to Gelfand, Kapranov, & Zelevinsky
and Balinski’s Theorem. For the edge flip-graph, we additionally show that the
vertex connectivity is at least as large as (and hence equal to) the minimum degree
(i.e., the minimum number of flippable edges in any full triangulation), provided
that n is large enough. Our methods also yield several other results: (i) The
edge flip graph can be covered by graphs of polytopes of dimension ⌈n/2−2⌉ (products
of associahedra) and the bistellar flip graph can be covered by graphs of polytopes
of dimension n−3 (products of secondary polytopes). (ii) A partial triangulation
is regular, if it has distance n−3 in the Hasse diagram of the partial order of
partial subdivisions from the trivial subdivision. (iii) All partial triangulations
of a point set are regular iff the partial order of partial subdivisions has height
n−3. (iv) There are arbitrarily large sets P with non-regular partial triangulations
and such that every proper subset has only regular triangulations, i.e., there
are no small certificates for the existence of non-regular triangulations.'
acknowledgement: "This is a full and revised version of [38] (on partial triangulations)
in Proceedings of the 36th Annual International Symposium on Computational Geometry
(SoCG‘20) and of some of the results in [37] (on full triangulations) in Proceedings
of the 31st Annual ACM-SIAM Symposium on Discrete Algorithms (SODA‘20).\r\nThis
research started at the 11th Gremo’s Workshop on Open Problems (GWOP), Alp Sellamatt,
Switzerland, June 24–28, 2013, motivated by a question posed by Filip Mori´c on
full triangulations. Research was supported by the Swiss National Science Foundation
within the collaborative DACH project Arrangements and Drawings as SNSF Project
200021E-171681, and by IST Austria and Berlin Free University during a sabbatical
stay of the second author. We thank Michael Joswig, Jesús De Loera, and Francisco
Santos for helpful discussions on the topics of this paper, and Daniel Bertschinger
and Valentin Stoppiello for carefully reading earlier versions and for many helpful
comments.\r\nOpen access funding provided by the Swiss Federal Institute of Technology
Zürich"
article_processing_charge: No
article_type: original
author:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Emo
full_name: Welzl, Emo
last_name: Welzl
citation:
ama: Wagner U, Welzl E. Connectivity of triangulation flip graphs in the plane.
Discrete & Computational Geometry. 2022;68(4):1227-1284. doi:10.1007/s00454-022-00436-2
apa: Wagner, U., & Welzl, E. (2022). Connectivity of triangulation flip graphs
in the plane. Discrete & Computational Geometry. Springer Nature. https://doi.org/10.1007/s00454-022-00436-2
chicago: Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs
in the Plane.” Discrete & Computational Geometry. Springer Nature,
2022. https://doi.org/10.1007/s00454-022-00436-2.
ieee: U. Wagner and E. Welzl, “Connectivity of triangulation flip graphs in the
plane,” Discrete & Computational Geometry, vol. 68, no. 4. Springer
Nature, pp. 1227–1284, 2022.
ista: Wagner U, Welzl E. 2022. Connectivity of triangulation flip graphs in the
plane. Discrete & Computational Geometry. 68(4), 1227–1284.
mla: Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs in the
Plane.” Discrete & Computational Geometry, vol. 68, no. 4, Springer
Nature, 2022, pp. 1227–84, doi:10.1007/s00454-022-00436-2.
short: U. Wagner, E. Welzl, Discrete & Computational Geometry 68 (2022) 1227–1284.
date_created: 2023-01-12T12:02:28Z
date_published: 2022-11-14T00:00:00Z
date_updated: 2023-08-04T08:51:08Z
day: '14'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.1007/s00454-022-00436-2
external_id:
isi:
- '000883222200003'
file:
- access_level: open_access
checksum: 307e879d09e52eddf5b225d0aaa9213a
content_type: application/pdf
creator: dernst
date_created: 2023-01-23T11:10:03Z
date_updated: 2023-01-23T11:10:03Z
file_id: '12345'
file_name: 2022_DiscreteCompGeometry_Wagner.pdf
file_size: 1747581
relation: main_file
success: 1
file_date_updated: 2023-01-23T11:10:03Z
has_accepted_license: '1'
intvolume: ' 68'
isi: 1
issue: '4'
keyword:
- Computational Theory and Mathematics
- Discrete Mathematics and Combinatorics
- Geometry and Topology
- Theoretical Computer Science
language:
- iso: eng
month: '11'
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oa_version: Published Version
page: 1227-1284
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issn:
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publication_status: published
publisher: Springer Nature
quality_controlled: '1'
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- id: '7990'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Connectivity of triangulation flip graphs in the plane
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 68
year: '2022'
...
---
_id: '14381'
abstract:
- lang: eng
text: Expander graphs (sparse but highly connected graphs) have, since their inception,
been the source of deep links between Mathematics and Computer Science as well
as applications to other areas. In recent years, a fascinating theory of high-dimensional
expanders has begun to emerge, which is still in a formative stage but has nonetheless
already lead to a number of striking results. Unlike for graphs, in higher dimensions
there is a rich array of non-equivalent notions of expansion (coboundary expansion,
cosystolic expansion, topological expansion, spectral expansion, etc.), with differents
strengths and applications. In this talk, we will survey this landscape of high-dimensional
expansion, with a focus on two main results. First, we will present Gromov’s Topological
Overlap Theorem, which asserts that coboundary expansion (a quantitative version
of vanishing mod 2 cohomology) implies topological expansion (roughly, the property
that for every map from a simplicial complex to a manifold of the same dimension,
the images of a positive fraction of the simplices have a point in common). Second,
we will outline a construction of bounded degree 2-dimensional topological expanders,
due to Kaufman, Kazhdan, and Lubotzky.
article_processing_charge: No
article_type: original
author:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Wagner U. High-dimensional expanders (after Gromov, Kaufman, Kazhdan, Lubotzky,
and others). Bulletin de la Societe Mathematique de France. 2022;438:281-294.
doi:10.24033/ast.1188
apa: Wagner, U. (2022). High-dimensional expanders (after Gromov, Kaufman, Kazhdan,
Lubotzky, and others). Bulletin de La Societe Mathematique de France. Societe
Mathematique de France. https://doi.org/10.24033/ast.1188
chicago: Wagner, Uli. “High-Dimensional Expanders (after Gromov, Kaufman, Kazhdan,
Lubotzky, and Others).” Bulletin de La Societe Mathematique de France.
Societe Mathematique de France, 2022. https://doi.org/10.24033/ast.1188.
ieee: U. Wagner, “High-dimensional expanders (after Gromov, Kaufman, Kazhdan, Lubotzky,
and others),” Bulletin de la Societe Mathematique de France, vol. 438.
Societe Mathematique de France, pp. 281–294, 2022.
ista: Wagner U. 2022. High-dimensional expanders (after Gromov, Kaufman, Kazhdan,
Lubotzky, and others). Bulletin de la Societe Mathematique de France. 438, 281–294.
mla: Wagner, Uli. “High-Dimensional Expanders (after Gromov, Kaufman, Kazhdan, Lubotzky,
and Others).” Bulletin de La Societe Mathematique de France, vol. 438,
Societe Mathematique de France, 2022, pp. 281–94, doi:10.24033/ast.1188.
short: U. Wagner, Bulletin de La Societe Mathematique de France 438 (2022) 281–294.
date_created: 2023-10-01T22:01:14Z
date_published: 2022-01-01T00:00:00Z
date_updated: 2023-10-03T08:04:03Z
day: '01'
department:
- _id: UlWa
doi: 10.24033/ast.1188
intvolume: ' 438'
language:
- iso: eng
month: '01'
oa_version: None
page: 281-294
publication: Bulletin de la Societe Mathematique de France
publication_identifier:
eissn:
- 2102-622X
issn:
- 0037-9484
publication_status: published
publisher: Societe Mathematique de France
quality_controlled: '1'
scopus_import: '1'
status: public
title: High-dimensional expanders (after Gromov, Kaufman, Kazhdan, Lubotzky, and others)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 438
year: '2022'
...
---
_id: '10220'
abstract:
- lang: eng
text: "We study conditions under which a finite simplicial complex K can be mapped
to ℝd without higher-multiplicity intersections. An almost r-embedding is a map
f: K → ℝd such that the images of any r pairwise disjoint simplices of K do not
have a common point. We show that if r is not a prime power and d ≥ 2r + 1, then
there is a counterexample to the topological Tverberg conjecture, i.e., there
is an almost r-embedding of the (d +1)(r − 1)-simplex in ℝd. This improves on
previous constructions of counterexamples (for d ≥ 3r) based on a series of papers
by M. Özaydin, M. Gromov, P. Blagojević, F. Frick, G. Ziegler, and the second
and fourth present authors.\r\n\r\nThe counterexamples are obtained by proving
the following algebraic criterion in codimension 2: If r ≥ 3 and if K is a finite
2(r − 1)-complex, then there exists an almost r-embedding K → ℝ2r if and only
if there exists a general position PL map f: K → ℝ2r such that the algebraic intersection
number of the f-images of any r pairwise disjoint simplices of K is zero. This
result can be restated in terms of a cohomological obstruction and extends an
analogous codimension 3 criterion by the second and fourth authors. As another
application, we classify ornaments f: S3 ⊔ S3 ⊔ S3 → ℝ5 up to ornament concordance.\r\n\r\nIt
follows from work of M. Freedman, V. Krushkal and P. Teichner that the analogous
criterion for r = 2 is false. We prove a lemma on singular higher-dimensional
Borromean rings, yielding an elementary proof of the counterexample."
acknowledgement: Research supported by the Swiss National Science Foundation (Project
SNSF-PP00P2-138948), by the Austrian Science Fund (FWF Project P31312-N35), by the
Russian Foundation for Basic Research (Grants No. 15-01-06302 and 19-01-00169),
by a Simons-IUM Fellowship, and by the D. Zimin Dynasty Foundation Grant. We would
like to thank E. Alkin, A. Klyachko, V. Krushkal, S. Melikhov, M. Tancer, P. Teichner
and anonymous referees for helpful comments and discussions.
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Sergey
full_name: Avvakumov, Sergey
id: 3827DAC8-F248-11E8-B48F-1D18A9856A87
last_name: Avvakumov
- first_name: Isaac
full_name: Mabillard, Isaac
id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
last_name: Mabillard
- first_name: Arkadiy B.
full_name: Skopenkov, Arkadiy B.
last_name: Skopenkov
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Avvakumov S, Mabillard I, Skopenkov AB, Wagner U. Eliminating higher-multiplicity
intersections. III. Codimension 2. Israel Journal of Mathematics. 2021;245:501–534.
doi:10.1007/s11856-021-2216-z
apa: Avvakumov, S., Mabillard, I., Skopenkov, A. B., & Wagner, U. (2021). Eliminating
higher-multiplicity intersections. III. Codimension 2. Israel Journal of Mathematics.
Springer Nature. https://doi.org/10.1007/s11856-021-2216-z
chicago: Avvakumov, Sergey, Isaac Mabillard, Arkadiy B. Skopenkov, and Uli Wagner.
“Eliminating Higher-Multiplicity Intersections. III. Codimension 2.” Israel
Journal of Mathematics. Springer Nature, 2021. https://doi.org/10.1007/s11856-021-2216-z.
ieee: S. Avvakumov, I. Mabillard, A. B. Skopenkov, and U. Wagner, “Eliminating higher-multiplicity
intersections. III. Codimension 2,” Israel Journal of Mathematics, vol.
245. Springer Nature, pp. 501–534, 2021.
ista: Avvakumov S, Mabillard I, Skopenkov AB, Wagner U. 2021. Eliminating higher-multiplicity
intersections. III. Codimension 2. Israel Journal of Mathematics. 245, 501–534.
mla: Avvakumov, Sergey, et al. “Eliminating Higher-Multiplicity Intersections. III.
Codimension 2.” Israel Journal of Mathematics, vol. 245, Springer Nature,
2021, pp. 501–534, doi:10.1007/s11856-021-2216-z.
short: S. Avvakumov, I. Mabillard, A.B. Skopenkov, U. Wagner, Israel Journal of
Mathematics 245 (2021) 501–534.
date_created: 2021-11-07T23:01:24Z
date_published: 2021-10-30T00:00:00Z
date_updated: 2023-08-14T11:43:55Z
day: '30'
department:
- _id: UlWa
doi: 10.1007/s11856-021-2216-z
external_id:
arxiv:
- '1511.03501'
isi:
- '000712942100013'
intvolume: ' 245'
isi: 1
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1511.03501
month: '10'
oa: 1
oa_version: Preprint
page: '501–534 '
project:
- _id: 26611F5C-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: P31312
name: Algorithms for Embeddings and Homotopy Theory
publication: Israel Journal of Mathematics
publication_identifier:
eissn:
- 1565-8511
issn:
- 0021-2172
publication_status: published
publisher: Springer Nature
quality_controlled: '1'
related_material:
record:
- id: '8183'
relation: earlier_version
status: public
- id: '9308'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Eliminating higher-multiplicity intersections. III. Codimension 2
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 245
year: '2021'
...
---
_id: '7806'
abstract:
- lang: eng
text: "We consider the following decision problem EMBEDk→d in computational topology
(where k ≤ d are fixed positive integers): Given a finite simplicial complex K
of dimension k, does there exist a (piecewise-linear) embedding of K into ℝd?\r\nThe
special case EMBED1→2 is graph planarity, which is decidable in linear time, as
shown by Hopcroft and Tarjan. In higher dimensions, EMBED2→3 and EMBED3→3 are
known to be decidable (as well as NP-hard), and recent results of Čadek et al.
in computational homotopy theory, in combination with the classical Haefliger–Weber
theorem in geometric topology, imply that EMBEDk→d can be solved in polynomial
time for any fixed pair (k, d) of dimensions in the so-called metastable range
.\r\nHere, by contrast, we prove that EMBEDk→d is algorithmically undecidable
for almost all pairs of dimensions outside the metastable range, namely for .
This almost completely resolves the decidability vs. undecidability of EMBEDk→d
in higher dimensions and establishes a sharp dichotomy between polynomial-time
solvability and undecidability.\r\nOur result complements (and in a wide range
of dimensions strengthens) earlier results of Matoušek, Tancer, and the second
author, who showed that EMBEDk→d is undecidable for 4 ≤ k ϵ {d – 1, d}, and NP-hard
for all remaining pairs (k, d) outside the metastable range and satisfying d ≥
4."
article_processing_charge: No
author:
- first_name: Marek
full_name: Filakovský, Marek
id: 3E8AF77E-F248-11E8-B48F-1D18A9856A87
last_name: Filakovský
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Stephan Y
full_name: Zhechev, Stephan Y
id: 3AA52972-F248-11E8-B48F-1D18A9856A87
last_name: Zhechev
citation:
ama: 'Filakovský M, Wagner U, Zhechev SY. Embeddability of simplicial complexes
is undecidable. In: Proceedings of the Annual ACM-SIAM Symposium on Discrete
Algorithms. Vol 2020-January. SIAM; 2020:767-785. doi:10.1137/1.9781611975994.47'
apa: 'Filakovský, M., Wagner, U., & Zhechev, S. Y. (2020). Embeddability of
simplicial complexes is undecidable. In Proceedings of the Annual ACM-SIAM
Symposium on Discrete Algorithms (Vol. 2020–January, pp. 767–785). Salt Lake
City, UT, United States: SIAM. https://doi.org/10.1137/1.9781611975994.47'
chicago: Filakovský, Marek, Uli Wagner, and Stephan Y Zhechev. “Embeddability of
Simplicial Complexes Is Undecidable.” In Proceedings of the Annual ACM-SIAM
Symposium on Discrete Algorithms, 2020–January:767–85. SIAM, 2020. https://doi.org/10.1137/1.9781611975994.47.
ieee: M. Filakovský, U. Wagner, and S. Y. Zhechev, “Embeddability of simplicial
complexes is undecidable,” in Proceedings of the Annual ACM-SIAM Symposium
on Discrete Algorithms, Salt Lake City, UT, United States, 2020, vol. 2020–January,
pp. 767–785.
ista: 'Filakovský M, Wagner U, Zhechev SY. 2020. Embeddability of simplicial complexes
is undecidable. Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms.
SODA: Symposium on Discrete Algorithms vol. 2020–January, 767–785.'
mla: Filakovský, Marek, et al. “Embeddability of Simplicial Complexes Is Undecidable.”
Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms, vol.
2020–January, SIAM, 2020, pp. 767–85, doi:10.1137/1.9781611975994.47.
short: M. Filakovský, U. Wagner, S.Y. Zhechev, in:, Proceedings of the Annual ACM-SIAM
Symposium on Discrete Algorithms, SIAM, 2020, pp. 767–785.
conference:
end_date: 2020-01-08
location: Salt Lake City, UT, United States
name: 'SODA: Symposium on Discrete Algorithms'
start_date: 2020-01-05
date_created: 2020-05-10T22:00:48Z
date_published: 2020-01-01T00:00:00Z
date_updated: 2021-01-12T08:15:38Z
day: '01'
department:
- _id: UlWa
doi: 10.1137/1.9781611975994.47
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1137/1.9781611975994.47
month: '01'
oa: 1
oa_version: Published Version
page: 767-785
project:
- _id: 26611F5C-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: P31312
name: Algorithms for Embeddings and Homotopy Theory
publication: Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms
publication_identifier:
isbn:
- '9781611975994'
publication_status: published
publisher: SIAM
quality_controlled: '1'
scopus_import: 1
status: public
title: Embeddability of simplicial complexes is undecidable
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 2020-January
year: '2020'
...
---
_id: '7807'
abstract:
- lang: eng
text: "In a straight-line embedded triangulation of a point set P in the plane,
removing an inner edge and—provided the resulting quadrilateral is convex—adding
the other diagonal is called an edge flip. The (edge) flip graph has all triangulations
as vertices, and a pair of triangulations is adjacent if they can be obtained
from each other by an edge flip. The goal of this paper is to contribute to a
better understanding of the flip graph, with an emphasis on its connectivity.\r\nFor
sets in general position, it is known that every triangulation allows at least
edge flips (a tight bound) which gives the minimum degree of any flip graph for
n points. We show that for every point set P in general position, the flip graph
is at least -vertex connected. Somewhat more strongly, we show that the vertex
connectivity equals the minimum degree occurring in the flip graph, i.e. the minimum
number of flippable edges in any triangulation of P, provided P is large enough.
Finally, we exhibit some of the geometry of the flip graph by showing that the
flip graph can be covered by 1-skeletons of polytopes of dimension (products of
associahedra).\r\nA corresponding result ((n – 3)-vertex connectedness) can be
shown for the bistellar flip graph of partial triangulations, i.e. the set of
all triangulations of subsets of P which contain all extreme points of P. This
will be treated separately in a second part."
article_processing_charge: No
arxiv: 1
author:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Emo
full_name: Welzl, Emo
last_name: Welzl
citation:
ama: 'Wagner U, Welzl E. Connectivity of triangulation flip graphs in the plane
(Part I: Edge flips). In: Proceedings of the Annual ACM-SIAM Symposium on Discrete
Algorithms. Vol 2020-January. SIAM; 2020:2823-2841. doi:10.1137/1.9781611975994.172'
apa: 'Wagner, U., & Welzl, E. (2020). Connectivity of triangulation flip graphs
in the plane (Part I: Edge flips). In Proceedings of the Annual ACM-SIAM Symposium
on Discrete Algorithms (Vol. 2020–January, pp. 2823–2841). Salt Lake City,
UT, United States: SIAM. https://doi.org/10.1137/1.9781611975994.172'
chicago: 'Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs
in the Plane (Part I: Edge Flips).” In Proceedings of the Annual ACM-SIAM Symposium
on Discrete Algorithms, 2020–January:2823–41. SIAM, 2020. https://doi.org/10.1137/1.9781611975994.172.'
ieee: 'U. Wagner and E. Welzl, “Connectivity of triangulation flip graphs in the
plane (Part I: Edge flips),” in Proceedings of the Annual ACM-SIAM Symposium
on Discrete Algorithms, Salt Lake City, UT, United States, 2020, vol. 2020–January,
pp. 2823–2841.'
ista: 'Wagner U, Welzl E. 2020. Connectivity of triangulation flip graphs in the
plane (Part I: Edge flips). Proceedings of the Annual ACM-SIAM Symposium on Discrete
Algorithms. SODA: Symposium on Discrete Algorithms vol. 2020–January, 2823–2841.'
mla: 'Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs in
the Plane (Part I: Edge Flips).” Proceedings of the Annual ACM-SIAM Symposium
on Discrete Algorithms, vol. 2020–January, SIAM, 2020, pp. 2823–41, doi:10.1137/1.9781611975994.172.'
short: U. Wagner, E. Welzl, in:, Proceedings of the Annual ACM-SIAM Symposium on
Discrete Algorithms, SIAM, 2020, pp. 2823–2841.
conference:
end_date: 2020-01-08
location: Salt Lake City, UT, United States
name: 'SODA: Symposium on Discrete Algorithms'
start_date: 2020-01-05
date_created: 2020-05-10T22:00:48Z
date_published: 2020-01-01T00:00:00Z
date_updated: 2023-08-04T08:51:07Z
day: '01'
department:
- _id: UlWa
doi: 10.1137/1.9781611975994.172
external_id:
arxiv:
- '2003.13557'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.1137/1.9781611975994.172
month: '01'
oa: 1
oa_version: Submitted Version
page: 2823-2841
publication: Proceedings of the Annual ACM-SIAM Symposium on Discrete Algorithms
publication_identifier:
isbn:
- '9781611975994'
publication_status: published
publisher: SIAM
quality_controlled: '1'
related_material:
record:
- id: '12129'
relation: later_version
status: public
scopus_import: 1
status: public
title: 'Connectivity of triangulation flip graphs in the plane (Part I: Edge flips)'
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 2020-January
year: '2020'
...
---
_id: '7990'
abstract:
- lang: eng
text: 'Given a finite point set P in general position in the plane, a full triangulation
is a maximal straight-line embedded plane graph on P. A partial triangulation
on P is a full triangulation of some subset P'' of P containing all extreme points
in P. A bistellar flip on a partial triangulation either flips an edge, removes
a non-extreme point of degree 3, or adds a point in P ⧵ P'' as vertex of degree
3. The bistellar flip graph has all partial triangulations as vertices, and a
pair of partial triangulations is adjacent if they can be obtained from one another
by a bistellar flip. The goal of this paper is to investigate the structure of
this graph, with emphasis on its connectivity. For sets P of n points in general
position, we show that the bistellar flip graph is (n-3)-connected, thereby answering,
for sets in general position, an open questions raised in a book (by De Loera,
Rambau, and Santos) and a survey (by Lee and Santos) on triangulations. This matches
the situation for the subfamily of regular triangulations (i.e., partial triangulations
obtained by lifting the points and projecting the lower convex hull), where (n-3)-connectivity
has been known since the late 1980s through the secondary polytope (Gelfand, Kapranov,
Zelevinsky) and Balinski’s Theorem. Our methods also yield the following results
(see the full version [Wagner and Welzl, 2020]): (i) The bistellar flip graph
can be covered by graphs of polytopes of dimension n-3 (products of secondary
polytopes). (ii) A partial triangulation is regular, if it has distance n-3 in
the Hasse diagram of the partial order of partial subdivisions from the trivial
subdivision. (iii) All partial triangulations are regular iff the trivial subdivision
has height n-3 in the partial order of partial subdivisions. (iv) There are arbitrarily
large sets P with non-regular partial triangulations, while every proper subset
has only regular triangulations, i.e., there are no small certificates for the
existence of non-regular partial triangulations (answering a question by F. Santos
in the unexpected direction).'
alternative_title:
- LIPIcs
article_number: 67:1 - 67:16
article_processing_charge: No
arxiv: 1
author:
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Emo
full_name: Welzl, Emo
last_name: Welzl
citation:
ama: 'Wagner U, Welzl E. Connectivity of triangulation flip graphs in the plane
(Part II: Bistellar flips). In: 36th International Symposium on Computational
Geometry. Vol 164. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2020.
doi:10.4230/LIPIcs.SoCG.2020.67'
apa: 'Wagner, U., & Welzl, E. (2020). Connectivity of triangulation flip graphs
in the plane (Part II: Bistellar flips). In 36th International Symposium on
Computational Geometry (Vol. 164). Zürich, Switzerland: Schloss Dagstuhl -
Leibniz-Zentrum für Informatik. https://doi.org/10.4230/LIPIcs.SoCG.2020.67'
chicago: 'Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs
in the Plane (Part II: Bistellar Flips).” In 36th International Symposium on
Computational Geometry, Vol. 164. Schloss Dagstuhl - Leibniz-Zentrum für Informatik,
2020. https://doi.org/10.4230/LIPIcs.SoCG.2020.67.'
ieee: 'U. Wagner and E. Welzl, “Connectivity of triangulation flip graphs in the
plane (Part II: Bistellar flips),” in 36th International Symposium on Computational
Geometry, Zürich, Switzerland, 2020, vol. 164.'
ista: 'Wagner U, Welzl E. 2020. Connectivity of triangulation flip graphs in the
plane (Part II: Bistellar flips). 36th International Symposium on Computational
Geometry. SoCG: Symposium on Computational Geometry, LIPIcs, vol. 164, 67:1-67:16.'
mla: 'Wagner, Uli, and Emo Welzl. “Connectivity of Triangulation Flip Graphs in
the Plane (Part II: Bistellar Flips).” 36th International Symposium on Computational
Geometry, vol. 164, 67:1-67:16, Schloss Dagstuhl - Leibniz-Zentrum für Informatik,
2020, doi:10.4230/LIPIcs.SoCG.2020.67.'
short: U. Wagner, E. Welzl, in:, 36th International Symposium on Computational Geometry,
Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2020.
conference:
end_date: 2020-06-26
location: Zürich, Switzerland
name: 'SoCG: Symposium on Computational Geometry'
start_date: 2020-06-22
date_created: 2020-06-22T09:14:19Z
date_published: 2020-06-01T00:00:00Z
date_updated: 2023-08-04T08:51:07Z
day: '01'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SoCG.2020.67
external_id:
arxiv:
- '2003.13557'
file:
- access_level: open_access
checksum: 3f6925be5f3dcdb3b14cab92f410edf7
content_type: application/pdf
creator: dernst
date_created: 2020-06-23T06:37:27Z
date_updated: 2020-07-14T12:48:06Z
file_id: '8003'
file_name: 2020_LIPIcsSoCG_Wagner.pdf
file_size: 793187
relation: main_file
file_date_updated: 2020-07-14T12:48:06Z
has_accepted_license: '1'
intvolume: ' 164'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
publication: 36th International Symposium on Computational Geometry
publication_identifier:
isbn:
- '9783959771436'
issn:
- '18688969'
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
quality_controlled: '1'
related_material:
record:
- id: '12129'
relation: later_version
status: public
scopus_import: 1
status: public
title: 'Connectivity of triangulation flip graphs in the plane (Part II: Bistellar
flips)'
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 164
year: '2020'
...
---
_id: '7992'
abstract:
- lang: eng
text: 'Let K be a convex body in ℝⁿ (i.e., a compact convex set with nonempty interior).
Given a point p in the interior of K, a hyperplane h passing through p is called
barycentric if p is the barycenter of K ∩ h. In 1961, Grünbaum raised the question
whether, for every K, there exists an interior point p through which there are
at least n+1 distinct barycentric hyperplanes. Two years later, this was seemingly
resolved affirmatively by showing that this is the case if p=p₀ is the point of
maximal depth in K. However, while working on a related question, we noticed that
one of the auxiliary claims in the proof is incorrect. Here, we provide a counterexample;
this re-opens Grünbaum’s question. It follows from known results that for n ≥
2, there are always at least three distinct barycentric cuts through the point
p₀ ∈ K of maximal depth. Using tools related to Morse theory we are able to improve
this bound: four distinct barycentric cuts through p₀ are guaranteed if n ≥ 3.'
alternative_title:
- LIPIcs
article_number: 62:1 - 62:16
article_processing_charge: No
arxiv: 1
author:
- first_name: Zuzana
full_name: Patakova, Zuzana
id: 48B57058-F248-11E8-B48F-1D18A9856A87
last_name: Patakova
orcid: 0000-0002-3975-1683
- first_name: Martin
full_name: Tancer, Martin
id: 38AC689C-F248-11E8-B48F-1D18A9856A87
last_name: Tancer
orcid: 0000-0002-1191-6714
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: 'Patakova Z, Tancer M, Wagner U. Barycentric cuts through a convex body. In:
36th International Symposium on Computational Geometry. Vol 164. Schloss
Dagstuhl - Leibniz-Zentrum für Informatik; 2020. doi:10.4230/LIPIcs.SoCG.2020.62'
apa: 'Patakova, Z., Tancer, M., & Wagner, U. (2020). Barycentric cuts through
a convex body. In 36th International Symposium on Computational Geometry
(Vol. 164). Zürich, Switzerland: Schloss Dagstuhl - Leibniz-Zentrum für Informatik.
https://doi.org/10.4230/LIPIcs.SoCG.2020.62'
chicago: Patakova, Zuzana, Martin Tancer, and Uli Wagner. “Barycentric Cuts through
a Convex Body.” In 36th International Symposium on Computational Geometry,
Vol. 164. Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2020. https://doi.org/10.4230/LIPIcs.SoCG.2020.62.
ieee: Z. Patakova, M. Tancer, and U. Wagner, “Barycentric cuts through a convex
body,” in 36th International Symposium on Computational Geometry, Zürich,
Switzerland, 2020, vol. 164.
ista: 'Patakova Z, Tancer M, Wagner U. 2020. Barycentric cuts through a convex body.
36th International Symposium on Computational Geometry. SoCG: Symposium on Computational
Geometry, LIPIcs, vol. 164, 62:1-62:16.'
mla: Patakova, Zuzana, et al. “Barycentric Cuts through a Convex Body.” 36th
International Symposium on Computational Geometry, vol. 164, 62:1-62:16, Schloss
Dagstuhl - Leibniz-Zentrum für Informatik, 2020, doi:10.4230/LIPIcs.SoCG.2020.62.
short: Z. Patakova, M. Tancer, U. Wagner, in:, 36th International Symposium on Computational
Geometry, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2020.
conference:
end_date: 2020-06-26
location: Zürich, Switzerland
name: 'SoCG: Symposium on Computational Geometry'
start_date: 2020-06-22
date_created: 2020-06-22T09:14:20Z
date_published: 2020-06-01T00:00:00Z
date_updated: 2021-01-12T08:16:23Z
day: '01'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SoCG.2020.62
external_id:
arxiv:
- '2003.13536'
file:
- access_level: open_access
checksum: ce1c9194139a664fb59d1efdfc88eaae
content_type: application/pdf
creator: dernst
date_created: 2020-06-23T06:45:52Z
date_updated: 2020-07-14T12:48:06Z
file_id: '8004'
file_name: 2020_LIPIcsSoCG_Patakova.pdf
file_size: 750318
relation: main_file
file_date_updated: 2020-07-14T12:48:06Z
has_accepted_license: '1'
intvolume: ' 164'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
publication: 36th International Symposium on Computational Geometry
publication_identifier:
isbn:
- '9783959771436'
issn:
- '18688969'
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
quality_controlled: '1'
scopus_import: 1
status: public
title: Barycentric cuts through a convex body
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 164
year: '2020'
...
---
_id: '9308'
acknowledgement: This research was carried out with the support of the Russian Foundation
for Basic Research(grant no. 19-01-00169)
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Sergey
full_name: Avvakumov, Sergey
id: 3827DAC8-F248-11E8-B48F-1D18A9856A87
last_name: Avvakumov
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Isaac
full_name: Mabillard, Isaac
id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
last_name: Mabillard
- first_name: A. B.
full_name: Skopenkov, A. B.
last_name: Skopenkov
citation:
ama: Avvakumov S, Wagner U, Mabillard I, Skopenkov AB. Eliminating higher-multiplicity
intersections, III. Codimension 2. Russian Mathematical Surveys. 2020;75(6):1156-1158.
doi:10.1070/RM9943
apa: Avvakumov, S., Wagner, U., Mabillard, I., & Skopenkov, A. B. (2020). Eliminating
higher-multiplicity intersections, III. Codimension 2. Russian Mathematical
Surveys. IOP Publishing. https://doi.org/10.1070/RM9943
chicago: Avvakumov, Sergey, Uli Wagner, Isaac Mabillard, and A. B. Skopenkov. “Eliminating
Higher-Multiplicity Intersections, III. Codimension 2.” Russian Mathematical
Surveys. IOP Publishing, 2020. https://doi.org/10.1070/RM9943.
ieee: S. Avvakumov, U. Wagner, I. Mabillard, and A. B. Skopenkov, “Eliminating higher-multiplicity
intersections, III. Codimension 2,” Russian Mathematical Surveys, vol.
75, no. 6. IOP Publishing, pp. 1156–1158, 2020.
ista: Avvakumov S, Wagner U, Mabillard I, Skopenkov AB. 2020. Eliminating higher-multiplicity
intersections, III. Codimension 2. Russian Mathematical Surveys. 75(6), 1156–1158.
mla: Avvakumov, Sergey, et al. “Eliminating Higher-Multiplicity Intersections, III.
Codimension 2.” Russian Mathematical Surveys, vol. 75, no. 6, IOP Publishing,
2020, pp. 1156–58, doi:10.1070/RM9943.
short: S. Avvakumov, U. Wagner, I. Mabillard, A.B. Skopenkov, Russian Mathematical
Surveys 75 (2020) 1156–1158.
date_created: 2021-04-04T22:01:22Z
date_published: 2020-12-01T00:00:00Z
date_updated: 2023-08-14T11:43:54Z
day: '01'
department:
- _id: UlWa
doi: 10.1070/RM9943
external_id:
arxiv:
- '1511.03501'
isi:
- '000625983100001'
intvolume: ' 75'
isi: 1
issue: '6'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1511.03501
month: '12'
oa: 1
oa_version: Preprint
page: 1156-1158
publication: Russian Mathematical Surveys
publication_identifier:
issn:
- 0036-0279
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
related_material:
record:
- id: '8183'
relation: earlier_version
status: public
- id: '10220'
relation: later_version
status: public
scopus_import: '1'
status: public
title: Eliminating higher-multiplicity intersections, III. Codimension 2
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 75
year: '2020'
...
---
_id: '5986'
abstract:
- lang: eng
text: "Given a triangulation of a point set in the plane, a flip deletes an edge
e whose removal leaves a convex quadrilateral, and replaces e by the opposite
diagonal of the quadrilateral. It is well known that any triangulation of a point
set can be reconfigured to any other triangulation by some sequence of flips.
We explore this question in the setting where each edge of a triangulation has
a label, and a flip transfers the label of the removed edge to the new edge. It
is not true that every labelled triangulation of a point set can be reconfigured
to every other labelled triangulation via a sequence of flips, but we characterize
when this is possible. There is an obvious necessary condition: for each label
l, if edge e has label l in the first triangulation and edge f has label l in
the second triangulation, then there must be some sequence of flips that moves
label l from e to f, ignoring all other labels. Bose, Lubiw, Pathak and Verdonschot
formulated the Orbit Conjecture, which states that this necessary condition is
also sufficient, i.e. that all labels can be simultaneously mapped to their destination
if and only if each label individually can be mapped to its destination. We prove
this conjecture. Furthermore, we give a polynomial-time algorithm (with \U0001D442(\U0001D45B8)
being a crude bound on the run-time) to find a sequence of flips to reconfigure
one labelled triangulation to another, if such a sequence exists, and we prove
an upper bound of \U0001D442(\U0001D45B7) on the length of the flip sequence.
Our proof uses the topological result that the sets of pairwise non-crossing edges
on a planar point set form a simplicial complex that is homeomorphic to a high-dimensional
ball (this follows from a result of Orden and Santos; we give a different proof
based on a shelling argument). The dual cell complex of this simplicial ball,
called the flip complex, has the usual flip graph as its 1-skeleton. We use properties
of the 2-skeleton of the flip complex to prove the Orbit Conjecture."
article_processing_charge: Yes (via OA deal)
article_type: original
arxiv: 1
author:
- first_name: Anna
full_name: Lubiw, Anna
last_name: Lubiw
- first_name: Zuzana
full_name: Masárová, Zuzana
id: 45CFE238-F248-11E8-B48F-1D18A9856A87
last_name: Masárová
orcid: 0000-0002-6660-1322
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Lubiw A, Masárová Z, Wagner U. A proof of the orbit conjecture for flipping
edge-labelled triangulations. Discrete & Computational Geometry. 2019;61(4):880-898.
doi:10.1007/s00454-018-0035-8
apa: Lubiw, A., Masárová, Z., & Wagner, U. (2019). A proof of the orbit conjecture
for flipping edge-labelled triangulations. Discrete & Computational Geometry.
Springer Nature. https://doi.org/10.1007/s00454-018-0035-8
chicago: Lubiw, Anna, Zuzana Masárová, and Uli Wagner. “A Proof of the Orbit Conjecture
for Flipping Edge-Labelled Triangulations.” Discrete & Computational Geometry.
Springer Nature, 2019. https://doi.org/10.1007/s00454-018-0035-8.
ieee: A. Lubiw, Z. Masárová, and U. Wagner, “A proof of the orbit conjecture for
flipping edge-labelled triangulations,” Discrete & Computational Geometry,
vol. 61, no. 4. Springer Nature, pp. 880–898, 2019.
ista: Lubiw A, Masárová Z, Wagner U. 2019. A proof of the orbit conjecture for flipping
edge-labelled triangulations. Discrete & Computational Geometry. 61(4), 880–898.
mla: Lubiw, Anna, et al. “A Proof of the Orbit Conjecture for Flipping Edge-Labelled
Triangulations.” Discrete & Computational Geometry, vol. 61, no. 4,
Springer Nature, 2019, pp. 880–98, doi:10.1007/s00454-018-0035-8.
short: A. Lubiw, Z. Masárová, U. Wagner, Discrete & Computational Geometry 61
(2019) 880–898.
date_created: 2019-02-14T11:54:08Z
date_published: 2019-06-01T00:00:00Z
date_updated: 2023-09-07T13:17:36Z
day: '01'
ddc:
- '000'
department:
- _id: UlWa
doi: 10.1007/s00454-018-0035-8
external_id:
arxiv:
- '1710.02741'
isi:
- '000466130000009'
file:
- access_level: open_access
checksum: e1bff88f1d77001b53b78c485ce048d7
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creator: dernst
date_created: 2019-02-14T11:57:22Z
date_updated: 2020-07-14T12:47:14Z
file_id: '5988'
file_name: 2018_DiscreteGeometry_Lubiw.pdf
file_size: 556276
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file_date_updated: 2020-07-14T12:47:14Z
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language:
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month: '06'
oa: 1
oa_version: Published Version
page: 880-898
project:
- _id: B67AFEDC-15C9-11EA-A837-991A96BB2854
name: IST Austria Open Access Fund
publication: Discrete & Computational Geometry
publication_identifier:
eissn:
- 1432-0444
issn:
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publication_status: published
publisher: Springer Nature
quality_controlled: '1'
related_material:
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relation: earlier_version
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scopus_import: '1'
status: public
title: A proof of the orbit conjecture for flipping edge-labelled triangulations
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 61
year: '2019'
...
---
_id: '6647'
abstract:
- lang: eng
text: The Tverberg theorem is one of the cornerstones of discrete geometry. It states
that, given a set X of at least (d+1)(r-1)+1 points in R^d, one can find a partition
X=X_1 cup ... cup X_r of X, such that the convex hulls of the X_i, i=1,...,r,
all share a common point. In this paper, we prove a strengthening of this theorem
that guarantees a partition which, in addition to the above, has the property
that the boundaries of full-dimensional convex hulls have pairwise nonempty intersections.
Possible generalizations and algorithmic aspects are also discussed. As a concrete
application, we show that any n points in the plane in general position span floor[n/3]
vertex-disjoint triangles that are pairwise crossing, meaning that their boundaries
have pairwise nonempty intersections; this number is clearly best possible. A
previous result of Alvarez-Rebollar et al. guarantees floor[n/6] pairwise crossing
triangles. Our result generalizes to a result about simplices in R^d,d >=2.
alternative_title:
- LIPIcs
arxiv: 1
author:
- first_name: Radoslav
full_name: Fulek, Radoslav
id: 39F3FFE4-F248-11E8-B48F-1D18A9856A87
last_name: Fulek
orcid: 0000-0001-8485-1774
- first_name: Bernd
full_name: Gärtner, Bernd
last_name: Gärtner
- first_name: Andrey
full_name: Kupavskii, Andrey
last_name: Kupavskii
- first_name: Pavel
full_name: Valtr, Pavel
last_name: Valtr
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: 'Fulek R, Gärtner B, Kupavskii A, Valtr P, Wagner U. The crossing Tverberg
theorem. In: 35th International Symposium on Computational Geometry. Vol
129. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2019:38:1-38:13. doi:10.4230/LIPICS.SOCG.2019.38'
apa: 'Fulek, R., Gärtner, B., Kupavskii, A., Valtr, P., & Wagner, U. (2019).
The crossing Tverberg theorem. In 35th International Symposium on Computational
Geometry (Vol. 129, p. 38:1-38:13). Portland, OR, United States: Schloss Dagstuhl
- Leibniz-Zentrum für Informatik. https://doi.org/10.4230/LIPICS.SOCG.2019.38'
chicago: Fulek, Radoslav, Bernd Gärtner, Andrey Kupavskii, Pavel Valtr, and Uli
Wagner. “The Crossing Tverberg Theorem.” In 35th International Symposium on
Computational Geometry, 129:38:1-38:13. Schloss Dagstuhl - Leibniz-Zentrum
für Informatik, 2019. https://doi.org/10.4230/LIPICS.SOCG.2019.38.
ieee: R. Fulek, B. Gärtner, A. Kupavskii, P. Valtr, and U. Wagner, “The crossing
Tverberg theorem,” in 35th International Symposium on Computational Geometry,
Portland, OR, United States, 2019, vol. 129, p. 38:1-38:13.
ista: 'Fulek R, Gärtner B, Kupavskii A, Valtr P, Wagner U. 2019. The crossing Tverberg
theorem. 35th International Symposium on Computational Geometry. SoCG 2019: Symposium
on Computational Geometry, LIPIcs, vol. 129, 38:1-38:13.'
mla: Fulek, Radoslav, et al. “The Crossing Tverberg Theorem.” 35th International
Symposium on Computational Geometry, vol. 129, Schloss Dagstuhl - Leibniz-Zentrum
für Informatik, 2019, p. 38:1-38:13, doi:10.4230/LIPICS.SOCG.2019.38.
short: R. Fulek, B. Gärtner, A. Kupavskii, P. Valtr, U. Wagner, in:, 35th International
Symposium on Computational Geometry, Schloss Dagstuhl - Leibniz-Zentrum für Informatik,
2019, p. 38:1-38:13.
conference:
end_date: 2019-06-21
location: Portland, OR, United States
name: 'SoCG 2019: Symposium on Computational Geometry'
start_date: 2019-06-18
date_created: 2019-07-17T10:35:04Z
date_published: 2019-06-01T00:00:00Z
date_updated: 2023-12-13T12:03:35Z
day: '01'
ddc:
- '000'
- '510'
department:
- _id: UlWa
doi: 10.4230/LIPICS.SOCG.2019.38
external_id:
arxiv:
- '1812.04911'
file:
- access_level: open_access
checksum: d6d017f8b41291b94d102294fa96ae9c
content_type: application/pdf
creator: dernst
date_created: 2019-07-24T06:54:52Z
date_updated: 2020-07-14T12:47:35Z
file_id: '6667'
file_name: 2019_LIPICS_Fulek.pdf
file_size: 559837
relation: main_file
file_date_updated: 2020-07-14T12:47:35Z
has_accepted_license: '1'
intvolume: ' 129'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
page: 38:1-38:13
project:
- _id: 261FA626-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: M02281
name: Eliminating intersections in drawings of graphs
publication: 35th International Symposium on Computational Geometry
publication_identifier:
isbn:
- '9783959771047'
issn:
- 1868-8969
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
quality_controlled: '1'
related_material:
record:
- id: '13974'
relation: later_version
status: public
scopus_import: 1
status: public
title: The crossing Tverberg theorem
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 129
year: '2019'
...
---
_id: '7093'
abstract:
- lang: eng
text: "In graph theory, as well as in 3-manifold topology, there exist several width-type
parameters to describe how \"simple\" or \"thin\" a given graph or 3-manifold
is. These parameters, such as pathwidth or treewidth for graphs, or the concept
of thin position for 3-manifolds, play an important role when studying algorithmic
problems; in particular, there is a variety of problems in computational 3-manifold
topology - some of them known to be computationally hard in general - that become
solvable in polynomial time as soon as the dual graph of the input triangulation
has bounded treewidth.\r\nIn view of these algorithmic results, it is natural
to ask whether every 3-manifold admits a triangulation of bounded treewidth. We
show that this is not the case, i.e., that there exists an infinite family of
closed 3-manifolds not admitting triangulations of bounded pathwidth or treewidth
(the latter implies the former, but we present two separate proofs).\r\nWe derive
these results from work of Agol, of Scharlemann and Thompson, and of Scharlemann,
Schultens and Saito by exhibiting explicit connections between the topology of
a 3-manifold M on the one hand and width-type parameters of the dual graphs of
triangulations of M on the other hand, answering a question that had been raised
repeatedly by researchers in computational 3-manifold topology. In particular,
we show that if a closed, orientable, irreducible, non-Haken 3-manifold M has
a triangulation of treewidth (resp. pathwidth) k then the Heegaard genus of M
is at most 18(k+1) (resp. 4(3k+1))."
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Kristóf
full_name: Huszár, Kristóf
id: 33C26278-F248-11E8-B48F-1D18A9856A87
last_name: Huszár
orcid: 0000-0002-5445-5057
- first_name: Jonathan
full_name: Spreer, Jonathan
last_name: Spreer
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Huszár K, Spreer J, Wagner U. On the treewidth of triangulated 3-manifolds.
Journal of Computational Geometry. 2019;10(2):70–98. doi:10.20382/JOGC.V10I2A5
apa: Huszár, K., Spreer, J., & Wagner, U. (2019). On the treewidth of triangulated
3-manifolds. Journal of Computational Geometry. Computational Geometry
Laborartoy. https://doi.org/10.20382/JOGC.V10I2A5
chicago: Huszár, Kristóf, Jonathan Spreer, and Uli Wagner. “On the Treewidth of
Triangulated 3-Manifolds.” Journal of Computational Geometry. Computational
Geometry Laborartoy, 2019. https://doi.org/10.20382/JOGC.V10I2A5.
ieee: K. Huszár, J. Spreer, and U. Wagner, “On the treewidth of triangulated 3-manifolds,”
Journal of Computational Geometry, vol. 10, no. 2. Computational Geometry
Laborartoy, pp. 70–98, 2019.
ista: Huszár K, Spreer J, Wagner U. 2019. On the treewidth of triangulated 3-manifolds.
Journal of Computational Geometry. 10(2), 70–98.
mla: Huszár, Kristóf, et al. “On the Treewidth of Triangulated 3-Manifolds.” Journal
of Computational Geometry, vol. 10, no. 2, Computational Geometry Laborartoy,
2019, pp. 70–98, doi:10.20382/JOGC.V10I2A5.
short: K. Huszár, J. Spreer, U. Wagner, Journal of Computational Geometry 10 (2019)
70–98.
date_created: 2019-11-23T12:14:09Z
date_published: 2019-11-01T00:00:00Z
date_updated: 2023-09-07T13:18:26Z
day: '01'
ddc:
- '514'
department:
- _id: UlWa
doi: 10.20382/JOGC.V10I2A5
external_id:
arxiv:
- '1712.00434'
file:
- access_level: open_access
checksum: c872d590d38d538404782bca20c4c3f5
content_type: application/pdf
creator: khuszar
date_created: 2019-11-23T12:35:16Z
date_updated: 2020-07-14T12:47:49Z
file_id: '7094'
file_name: 479-1917-1-PB.pdf
file_size: 857590
relation: main_file
file_date_updated: 2020-07-14T12:47:49Z
has_accepted_license: '1'
intvolume: ' 10'
issue: '2'
language:
- iso: eng
month: '11'
oa: 1
oa_version: Published Version
page: 70–98
publication: Journal of Computational Geometry
publication_identifier:
issn:
- 1920-180X
publication_status: published
publisher: Computational Geometry Laborartoy
quality_controlled: '1'
related_material:
record:
- id: '285'
relation: earlier_version
status: public
- id: '8032'
relation: part_of_dissertation
status: public
status: public
title: On the treewidth of triangulated 3-manifolds
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 10
year: '2019'
...
---
_id: '7108'
abstract:
- lang: eng
text: We prove that for every d ≥ 2, deciding if a pure, d-dimensional, simplicial
complex is shellable is NP-hard, hence NP-complete. This resolves a question raised,
e.g., by Danaraj and Klee in 1978. Our reduction also yields that for every d
≥ 2 and k ≥ 0, deciding if a pure, d-dimensional, simplicial complex is k-decomposable
is NP-hard. For d ≥ 3, both problems remain NP-hard when restricted to contractible
pure d-dimensional complexes. Another simple corollary of our result is that it
is NP-hard to decide whether a given poset is CL-shellable.
article_number: '21'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Xavier
full_name: Goaoc, Xavier
last_name: Goaoc
- first_name: Pavel
full_name: Patak, Pavel
id: B593B804-1035-11EA-B4F1-947645A5BB83
last_name: Patak
- first_name: Zuzana
full_name: Patakova, Zuzana
id: 48B57058-F248-11E8-B48F-1D18A9856A87
last_name: Patakova
orcid: 0000-0002-3975-1683
- first_name: Martin
full_name: Tancer, Martin
last_name: Tancer
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Goaoc X, Patak P, Patakova Z, Tancer M, Wagner U. Shellability is NP-complete.
Journal of the ACM. 2019;66(3). doi:10.1145/3314024
apa: Goaoc, X., Patak, P., Patakova, Z., Tancer, M., & Wagner, U. (2019). Shellability
is NP-complete. Journal of the ACM. ACM. https://doi.org/10.1145/3314024
chicago: Goaoc, Xavier, Pavel Patak, Zuzana Patakova, Martin Tancer, and Uli Wagner.
“Shellability Is NP-Complete.” Journal of the ACM. ACM, 2019. https://doi.org/10.1145/3314024.
ieee: X. Goaoc, P. Patak, Z. Patakova, M. Tancer, and U. Wagner, “Shellability is
NP-complete,” Journal of the ACM, vol. 66, no. 3. ACM, 2019.
ista: Goaoc X, Patak P, Patakova Z, Tancer M, Wagner U. 2019. Shellability is NP-complete.
Journal of the ACM. 66(3), 21.
mla: Goaoc, Xavier, et al. “Shellability Is NP-Complete.” Journal of the ACM,
vol. 66, no. 3, 21, ACM, 2019, doi:10.1145/3314024.
short: X. Goaoc, P. Patak, Z. Patakova, M. Tancer, U. Wagner, Journal of the ACM
66 (2019).
date_created: 2019-11-26T10:13:59Z
date_published: 2019-06-01T00:00:00Z
date_updated: 2023-09-06T11:10:58Z
day: '01'
department:
- _id: UlWa
doi: 10.1145/3314024
external_id:
arxiv:
- '1711.08436'
isi:
- '000495406300007'
intvolume: ' 66'
isi: 1
issue: '3'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/pdf/1711.08436.pdf
month: '06'
oa: 1
oa_version: Preprint
publication: Journal of the ACM
publication_identifier:
issn:
- 0004-5411
publication_status: published
publisher: ACM
quality_controlled: '1'
related_material:
record:
- id: '184'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Shellability is NP-complete
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 66
year: '2019'
...
---
_id: '184'
abstract:
- lang: eng
text: We prove that for every d ≥ 2, deciding if a pure, d-dimensional, simplicial
complex is shellable is NP-hard, hence NP-complete. This resolves a question raised,
e.g., by Danaraj and Klee in 1978. Our reduction also yields that for every d
≥ 2 and k ≥ 0, deciding if a pure, d-dimensional, simplicial complex is k-decomposable
is NP-hard. For d ≥ 3, both problems remain NP-hard when restricted to contractible
pure d-dimensional complexes.
acknowledgement: 'Partially supported by the project EMBEDS II (CZ: 7AMB17FR029, FR:
38087RM) of Czech-French collaboration.'
alternative_title:
- Leibniz International Proceedings in Information, LIPIcs
author:
- first_name: Xavier
full_name: Goaoc, Xavier
last_name: Goaoc
- first_name: Pavel
full_name: Paták, Pavel
last_name: Paták
- first_name: Zuzana
full_name: Patakova, Zuzana
id: 48B57058-F248-11E8-B48F-1D18A9856A87
last_name: Patakova
orcid: 0000-0002-3975-1683
- first_name: Martin
full_name: Tancer, Martin
id: 38AC689C-F248-11E8-B48F-1D18A9856A87
last_name: Tancer
orcid: 0000-0002-1191-6714
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: 'Goaoc X, Paták P, Patakova Z, Tancer M, Wagner U. Shellability is NP-complete.
In: Vol 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2018:41:1-41:16.
doi:10.4230/LIPIcs.SoCG.2018.41'
apa: 'Goaoc, X., Paták, P., Patakova, Z., Tancer, M., & Wagner, U. (2018). Shellability
is NP-complete (Vol. 99, p. 41:1-41:16). Presented at the SoCG: Symposium on Computational
Geometry, Budapest, Hungary: Schloss Dagstuhl - Leibniz-Zentrum für Informatik.
https://doi.org/10.4230/LIPIcs.SoCG.2018.41'
chicago: Goaoc, Xavier, Pavel Paták, Zuzana Patakova, Martin Tancer, and Uli Wagner.
“Shellability Is NP-Complete,” 99:41:1-41:16. Schloss Dagstuhl - Leibniz-Zentrum
für Informatik, 2018. https://doi.org/10.4230/LIPIcs.SoCG.2018.41.
ieee: 'X. Goaoc, P. Paták, Z. Patakova, M. Tancer, and U. Wagner, “Shellability
is NP-complete,” presented at the SoCG: Symposium on Computational Geometry, Budapest,
Hungary, 2018, vol. 99, p. 41:1-41:16.'
ista: 'Goaoc X, Paták P, Patakova Z, Tancer M, Wagner U. 2018. Shellability is NP-complete.
SoCG: Symposium on Computational Geometry, Leibniz International Proceedings in
Information, LIPIcs, vol. 99, 41:1-41:16.'
mla: Goaoc, Xavier, et al. Shellability Is NP-Complete. Vol. 99, Schloss
Dagstuhl - Leibniz-Zentrum für Informatik, 2018, p. 41:1-41:16, doi:10.4230/LIPIcs.SoCG.2018.41.
short: X. Goaoc, P. Paták, Z. Patakova, M. Tancer, U. Wagner, in:, Schloss Dagstuhl
- Leibniz-Zentrum für Informatik, 2018, p. 41:1-41:16.
conference:
end_date: 2018-06-14
location: Budapest, Hungary
name: 'SoCG: Symposium on Computational Geometry'
start_date: 2018-06-11
date_created: 2018-12-11T11:45:04Z
date_published: 2018-06-11T00:00:00Z
date_updated: 2023-09-06T11:10:57Z
day: '11'
ddc:
- '516'
- '000'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SoCG.2018.41
file:
- access_level: open_access
checksum: d12bdd60f04a57307867704b5f930afd
content_type: application/pdf
creator: dernst
date_created: 2018-12-17T16:35:02Z
date_updated: 2020-07-14T12:45:18Z
file_id: '5725'
file_name: 2018_LIPIcs_Goaoc.pdf
file_size: 718414
relation: main_file
file_date_updated: 2020-07-14T12:45:18Z
has_accepted_license: '1'
intvolume: ' 99'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
page: 41:1 - 41:16
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
publist_id: '7736'
quality_controlled: '1'
related_material:
record:
- id: '7108'
relation: later_version
status: public
scopus_import: 1
status: public
title: Shellability is NP-complete
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 99
year: '2018'
...
---
_id: '285'
abstract:
- lang: eng
text: In graph theory, as well as in 3-manifold topology, there exist several width-type
parameters to describe how "simple" or "thin" a given graph
or 3-manifold is. These parameters, such as pathwidth or treewidth for graphs,
or the concept of thin position for 3-manifolds, play an important role when studying
algorithmic problems; in particular, there is a variety of problems in computational
3-manifold topology - some of them known to be computationally hard in general
- that become solvable in polynomial time as soon as the dual graph of the input
triangulation has bounded treewidth. In view of these algorithmic results, it
is natural to ask whether every 3-manifold admits a triangulation of bounded treewidth.
We show that this is not the case, i.e., that there exists an infinite family
of closed 3-manifolds not admitting triangulations of bounded pathwidth or treewidth
(the latter implies the former, but we present two separate proofs). We derive
these results from work of Agol and of Scharlemann and Thompson, by exhibiting
explicit connections between the topology of a 3-manifold M on the one hand and
width-type parameters of the dual graphs of triangulations of M on the other hand,
answering a question that had been raised repeatedly by researchers in computational
3-manifold topology. In particular, we show that if a closed, orientable, irreducible,
non-Haken 3-manifold M has a triangulation of treewidth (resp. pathwidth) k then
the Heegaard genus of M is at most 48(k+1) (resp. 4(3k+1)).
acknowledgement: Research of the second author was supported by the Einstein Foundation
(project “Einstein Visiting Fellow Santos”) and by the Simons Foundation (“Simons
Visiting Professors” program).
alternative_title:
- LIPIcs
article_number: '46'
article_processing_charge: No
arxiv: 1
author:
- first_name: Kristóf
full_name: Huszár, Kristóf
id: 33C26278-F248-11E8-B48F-1D18A9856A87
last_name: Huszár
orcid: 0000-0002-5445-5057
- first_name: Jonathan
full_name: Spreer, Jonathan
last_name: Spreer
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: 'Huszár K, Spreer J, Wagner U. On the treewidth of triangulated 3-manifolds.
In: Vol 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2018. doi:10.4230/LIPIcs.SoCG.2018.46'
apa: 'Huszár, K., Spreer, J., & Wagner, U. (2018). On the treewidth of triangulated
3-manifolds (Vol. 99). Presented at the SoCG: Symposium on Computational Geometry,
Budapest, Hungary: Schloss Dagstuhl - Leibniz-Zentrum für Informatik. https://doi.org/10.4230/LIPIcs.SoCG.2018.46'
chicago: Huszár, Kristóf, Jonathan Spreer, and Uli Wagner. “On the Treewidth of
Triangulated 3-Manifolds,” Vol. 99. Schloss Dagstuhl - Leibniz-Zentrum für Informatik,
2018. https://doi.org/10.4230/LIPIcs.SoCG.2018.46.
ieee: 'K. Huszár, J. Spreer, and U. Wagner, “On the treewidth of triangulated 3-manifolds,”
presented at the SoCG: Symposium on Computational Geometry, Budapest, Hungary,
2018, vol. 99.'
ista: 'Huszár K, Spreer J, Wagner U. 2018. On the treewidth of triangulated 3-manifolds.
SoCG: Symposium on Computational Geometry, LIPIcs, vol. 99, 46.'
mla: Huszár, Kristóf, et al. On the Treewidth of Triangulated 3-Manifolds.
Vol. 99, 46, Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2018, doi:10.4230/LIPIcs.SoCG.2018.46.
short: K. Huszár, J. Spreer, U. Wagner, in:, Schloss Dagstuhl - Leibniz-Zentrum
für Informatik, 2018.
conference:
end_date: 2018-06-14
location: Budapest, Hungary
name: 'SoCG: Symposium on Computational Geometry'
start_date: 2018-06-11
date_created: 2018-12-11T11:45:37Z
date_published: 2018-06-01T00:00:00Z
date_updated: 2023-09-06T11:13:41Z
day: '01'
ddc:
- '516'
- '000'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SoCG.2018.46
external_id:
arxiv:
- '1712.00434'
file:
- access_level: open_access
checksum: 530d084116778135d5bffaa317479cac
content_type: application/pdf
creator: dernst
date_created: 2018-12-17T15:32:38Z
date_updated: 2020-07-14T12:45:51Z
file_id: '5713'
file_name: 2018_LIPIcs_Huszar.pdf
file_size: 642522
relation: main_file
file_date_updated: 2020-07-14T12:45:51Z
has_accepted_license: '1'
intvolume: ' 99'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Submitted Version
publication_identifier:
issn:
- '18688969'
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
publist_id: '7614'
quality_controlled: '1'
related_material:
record:
- id: '7093'
relation: later_version
status: public
scopus_import: 1
status: public
title: On the treewidth of triangulated 3-manifolds
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: conference
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 99
year: '2018'
...
---
_id: '425'
abstract:
- lang: eng
text: 'We show that the following algorithmic problem is decidable: given a 2-dimensional
simplicial complex, can it be embedded (topologically, or equivalently, piecewise
linearly) in R3? By a known reduction, it suffices to decide the embeddability
of a given triangulated 3-manifold X into the 3-sphere S3. The main step, which
allows us to simplify X and recurse, is in proving that if X can be embedded in
S3, then there is also an embedding in which X has a short meridian, that is,
an essential curve in the boundary of X bounding a disk in S3 \ X with length
bounded by a computable function of the number of tetrahedra of X.'
article_number: '5'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Jiří
full_name: Matoušek, Jiří
last_name: Matoušek
- first_name: Eric
full_name: Sedgwick, Eric
last_name: Sedgwick
- first_name: Martin
full_name: Tancer, Martin
id: 38AC689C-F248-11E8-B48F-1D18A9856A87
last_name: Tancer
orcid: 0000-0002-1191-6714
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Matoušek J, Sedgwick E, Tancer M, Wagner U. Embeddability in the 3-Sphere is
decidable. Journal of the ACM. 2018;65(1). doi:10.1145/3078632
apa: Matoušek, J., Sedgwick, E., Tancer, M., & Wagner, U. (2018). Embeddability
in the 3-Sphere is decidable. Journal of the ACM. ACM. https://doi.org/10.1145/3078632
chicago: Matoušek, Jiří, Eric Sedgwick, Martin Tancer, and Uli Wagner. “Embeddability
in the 3-Sphere Is Decidable.” Journal of the ACM. ACM, 2018. https://doi.org/10.1145/3078632.
ieee: J. Matoušek, E. Sedgwick, M. Tancer, and U. Wagner, “Embeddability in the
3-Sphere is decidable,” Journal of the ACM, vol. 65, no. 1. ACM, 2018.
ista: Matoušek J, Sedgwick E, Tancer M, Wagner U. 2018. Embeddability in the 3-Sphere
is decidable. Journal of the ACM. 65(1), 5.
mla: Matoušek, Jiří, et al. “Embeddability in the 3-Sphere Is Decidable.” Journal
of the ACM, vol. 65, no. 1, 5, ACM, 2018, doi:10.1145/3078632.
short: J. Matoušek, E. Sedgwick, M. Tancer, U. Wagner, Journal of the ACM 65 (2018).
date_created: 2018-12-11T11:46:24Z
date_published: 2018-01-01T00:00:00Z
date_updated: 2023-09-11T13:38:49Z
day: '01'
department:
- _id: UlWa
doi: 10.1145/3078632
ec_funded: 1
external_id:
arxiv:
- '1402.0815'
isi:
- '000425685900006'
intvolume: ' 65'
isi: 1
issue: '1'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://arxiv.org/abs/1402.0815
month: '01'
oa: 1
oa_version: Preprint
project:
- _id: 25681D80-B435-11E9-9278-68D0E5697425
call_identifier: FP7
grant_number: '291734'
name: International IST Postdoc Fellowship Programme
publication: Journal of the ACM
publication_status: published
publisher: ACM
publist_id: '7398'
quality_controlled: '1'
related_material:
record:
- id: '2157'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Embeddability in the 3-Sphere is decidable
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 65
year: '2018'
...
---
_id: '6774'
abstract:
- lang: eng
text: "A central problem of algebraic topology is to understand the homotopy groups
\ \U0001D70B\U0001D451(\U0001D44B) of a topological space X. For the computational
version of the problem, it is well known that there is no algorithm to decide
whether the fundamental group \U0001D70B1(\U0001D44B) of a given finite simplicial
complex X is trivial. On the other hand, there are several algorithms that, given
a finite simplicial complex X that is simply connected (i.e., with \U0001D70B1(\U0001D44B)
\ trivial), compute the higher homotopy group \U0001D70B\U0001D451(\U0001D44B)
\ for any given \U0001D451≥2 . However, these algorithms come with a caveat:
They compute the isomorphism type of \U0001D70B\U0001D451(\U0001D44B) , \U0001D451≥2
\ as an abstract finitely generated abelian group given by generators and relations,
but they work with very implicit representations of the elements of \U0001D70B\U0001D451(\U0001D44B)
. Converting elements of this abstract group into explicit geometric maps from
the d-dimensional sphere \U0001D446\U0001D451 to X has been one of the main
unsolved problems in the emerging field of computational homotopy theory. Here
we present an algorithm that, given a simply connected space X, computes \U0001D70B\U0001D451(\U0001D44B)
\ and represents its elements as simplicial maps from a suitable triangulation
of the d-sphere \U0001D446\U0001D451 to X. For fixed d, the algorithm runs
in time exponential in size(\U0001D44B) , the number of simplices of X. Moreover,
we prove that this is optimal: For every fixed \U0001D451≥2 , we construct a
family of simply connected spaces X such that for any simplicial map representing
a generator of \U0001D70B\U0001D451(\U0001D44B) , the size of the triangulation
of \U0001D446\U0001D451 on which the map is defined, is exponential in size(\U0001D44B)
."
article_type: original
author:
- first_name: Marek
full_name: Filakovský, Marek
id: 3E8AF77E-F248-11E8-B48F-1D18A9856A87
last_name: Filakovský
- first_name: Peter
full_name: Franek, Peter
id: 473294AE-F248-11E8-B48F-1D18A9856A87
last_name: Franek
orcid: 0000-0001-8878-8397
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
- first_name: Stephan Y
full_name: Zhechev, Stephan Y
id: 3AA52972-F248-11E8-B48F-1D18A9856A87
last_name: Zhechev
citation:
ama: Filakovský M, Franek P, Wagner U, Zhechev SY. Computing simplicial representatives
of homotopy group elements. Journal of Applied and Computational Topology.
2018;2(3-4):177-231. doi:10.1007/s41468-018-0021-5
apa: Filakovský, M., Franek, P., Wagner, U., & Zhechev, S. Y. (2018). Computing
simplicial representatives of homotopy group elements. Journal of Applied and
Computational Topology. Springer. https://doi.org/10.1007/s41468-018-0021-5
chicago: Filakovský, Marek, Peter Franek, Uli Wagner, and Stephan Y Zhechev. “Computing
Simplicial Representatives of Homotopy Group Elements.” Journal of Applied
and Computational Topology. Springer, 2018. https://doi.org/10.1007/s41468-018-0021-5.
ieee: M. Filakovský, P. Franek, U. Wagner, and S. Y. Zhechev, “Computing simplicial
representatives of homotopy group elements,” Journal of Applied and Computational
Topology, vol. 2, no. 3–4. Springer, pp. 177–231, 2018.
ista: Filakovský M, Franek P, Wagner U, Zhechev SY. 2018. Computing simplicial representatives
of homotopy group elements. Journal of Applied and Computational Topology. 2(3–4),
177–231.
mla: Filakovský, Marek, et al. “Computing Simplicial Representatives of Homotopy
Group Elements.” Journal of Applied and Computational Topology, vol. 2,
no. 3–4, Springer, 2018, pp. 177–231, doi:10.1007/s41468-018-0021-5.
short: M. Filakovský, P. Franek, U. Wagner, S.Y. Zhechev, Journal of Applied and
Computational Topology 2 (2018) 177–231.
date_created: 2019-08-08T06:47:40Z
date_published: 2018-12-01T00:00:00Z
date_updated: 2023-09-07T13:10:36Z
day: '01'
ddc:
- '514'
department:
- _id: UlWa
doi: 10.1007/s41468-018-0021-5
file:
- access_level: open_access
checksum: cf9e7fcd2a113dd4828774fc75cdb7e8
content_type: application/pdf
creator: dernst
date_created: 2019-08-08T06:55:21Z
date_updated: 2020-07-14T12:47:40Z
file_id: '6775'
file_name: 2018_JourAppliedComputTopology_Filakovsky.pdf
file_size: 1056278
relation: main_file
file_date_updated: 2020-07-14T12:47:40Z
has_accepted_license: '1'
intvolume: ' 2'
issue: 3-4
language:
- iso: eng
month: '12'
oa: 1
oa_version: Published Version
page: 177-231
project:
- _id: 25F8B9BC-B435-11E9-9278-68D0E5697425
call_identifier: FWF
grant_number: M01980
name: Robust invariants of Nonlinear Systems
- _id: 3AC91DDA-15DF-11EA-824D-93A3E7B544D1
call_identifier: FWF
name: FWF Open Access Fund
publication: Journal of Applied and Computational Topology
publication_identifier:
eissn:
- 2367-1734
issn:
- 2367-1726
publication_status: published
publisher: Springer
quality_controlled: '1'
related_material:
record:
- id: '6681'
relation: dissertation_contains
status: public
status: public
title: Computing simplicial representatives of homotopy group elements
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 2
year: '2018'
...
---
_id: '742'
abstract:
- lang: eng
text: 'We give a detailed and easily accessible proof of Gromov’s Topological Overlap
Theorem. Let X be a finite simplicial complex or, more generally, a finite polyhedral
cell complex of dimension d. Informally, the theorem states that if X has sufficiently
strong higher-dimensional expansion properties (which generalize edge expansion
of graphs and are defined in terms of cellular cochains of X) then X has the following
topological overlap property: for every continuous map (Formula presented.) there
exists a point (Formula presented.) that is contained in the images of a positive
fraction (Formula presented.) of the d-cells of X. More generally, the conclusion
holds if (Formula presented.) is replaced by any d-dimensional piecewise-linear
manifold M, with a constant (Formula presented.) that depends only on d and on
the expansion properties of X, but not on M.'
article_processing_charge: Yes (via OA deal)
author:
- first_name: Dominic
full_name: Dotterrer, Dominic
last_name: Dotterrer
- first_name: Tali
full_name: Kaufman, Tali
last_name: Kaufman
- first_name: Uli
full_name: Wagner, Uli
id: 36690CA2-F248-11E8-B48F-1D18A9856A87
last_name: Wagner
orcid: 0000-0002-1494-0568
citation:
ama: Dotterrer D, Kaufman T, Wagner U. On expansion and topological overlap. Geometriae
Dedicata. 2018;195(1):307–317. doi:10.1007/s10711-017-0291-4
apa: Dotterrer, D., Kaufman, T., & Wagner, U. (2018). On expansion and topological
overlap. Geometriae Dedicata. Springer. https://doi.org/10.1007/s10711-017-0291-4
chicago: Dotterrer, Dominic, Tali Kaufman, and Uli Wagner. “On Expansion and Topological
Overlap.” Geometriae Dedicata. Springer, 2018. https://doi.org/10.1007/s10711-017-0291-4.
ieee: D. Dotterrer, T. Kaufman, and U. Wagner, “On expansion and topological overlap,”
Geometriae Dedicata, vol. 195, no. 1. Springer, pp. 307–317, 2018.
ista: Dotterrer D, Kaufman T, Wagner U. 2018. On expansion and topological overlap.
Geometriae Dedicata. 195(1), 307–317.
mla: Dotterrer, Dominic, et al. “On Expansion and Topological Overlap.” Geometriae
Dedicata, vol. 195, no. 1, Springer, 2018, pp. 307–317, doi:10.1007/s10711-017-0291-4.
short: D. Dotterrer, T. Kaufman, U. Wagner, Geometriae Dedicata 195 (2018) 307–317.
date_created: 2018-12-11T11:48:16Z
date_published: 2018-08-01T00:00:00Z
date_updated: 2023-09-27T12:29:57Z
day: '01'
ddc:
- '514'
- '516'
department:
- _id: UlWa
doi: 10.1007/s10711-017-0291-4
external_id:
isi:
- '000437122700017'
file:
- access_level: open_access
checksum: d2f70fc132156504aa4c626aa378a7ab
content_type: application/pdf
creator: kschuh
date_created: 2019-01-15T13:44:05Z
date_updated: 2020-07-14T12:47:58Z
file_id: '5835'
file_name: s10711-017-0291-4.pdf
file_size: 412486
relation: main_file
file_date_updated: 2020-07-14T12:47:58Z
has_accepted_license: '1'
intvolume: ' 195'
isi: 1
issue: '1'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
page: 307–317
project:
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grant_number: PP00P2_138948
name: 'Embeddings in Higher Dimensions: Algorithms and Combinatorics'
publication: Geometriae Dedicata
publication_status: published
publisher: Springer
publist_id: '6925'
pubrep_id: '912'
quality_controlled: '1'
related_material:
record:
- id: '1378'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: On expansion and topological overlap
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
volume: 195
year: '2018'
...