---
_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. <i>Israel Journal of Mathematics</i>. 2021;245:501–534.
    doi:<a href="https://doi.org/10.1007/s11856-021-2216-z">10.1007/s11856-021-2216-z</a>
  apa: Avvakumov, S., Mabillard, I., Skopenkov, A. B., &#38; Wagner, U. (2021). Eliminating
    higher-multiplicity intersections. III. Codimension 2. <i>Israel Journal of Mathematics</i>.
    Springer Nature. <a href="https://doi.org/10.1007/s11856-021-2216-z">https://doi.org/10.1007/s11856-021-2216-z</a>
  chicago: Avvakumov, Sergey, Isaac Mabillard, Arkadiy B. Skopenkov, and Uli Wagner.
    “Eliminating Higher-Multiplicity Intersections. III. Codimension 2.” <i>Israel
    Journal of Mathematics</i>. Springer Nature, 2021. <a href="https://doi.org/10.1007/s11856-021-2216-z">https://doi.org/10.1007/s11856-021-2216-z</a>.
  ieee: S. Avvakumov, I. Mabillard, A. B. Skopenkov, and U. Wagner, “Eliminating higher-multiplicity
    intersections. III. Codimension 2,” <i>Israel Journal of Mathematics</i>, 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.” <i>Israel Journal of Mathematics</i>, vol. 245, Springer Nature,
    2021, pp. 501–534, doi:<a href="https://doi.org/10.1007/s11856-021-2216-z">10.1007/s11856-021-2216-z</a>.
  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: '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. <i>Russian Mathematical Surveys</i>. 2020;75(6):1156-1158.
    doi:<a href="https://doi.org/10.1070/RM9943">10.1070/RM9943</a>
  apa: Avvakumov, S., Wagner, U., Mabillard, I., &#38; Skopenkov, A. B. (2020). Eliminating
    higher-multiplicity intersections, III. Codimension 2. <i>Russian Mathematical
    Surveys</i>. IOP Publishing. <a href="https://doi.org/10.1070/RM9943">https://doi.org/10.1070/RM9943</a>
  chicago: Avvakumov, Sergey, Uli Wagner, Isaac Mabillard, and A. B. Skopenkov. “Eliminating
    Higher-Multiplicity Intersections, III. Codimension 2.” <i>Russian Mathematical
    Surveys</i>. IOP Publishing, 2020. <a href="https://doi.org/10.1070/RM9943">https://doi.org/10.1070/RM9943</a>.
  ieee: S. Avvakumov, U. Wagner, I. Mabillard, and A. B. Skopenkov, “Eliminating higher-multiplicity
    intersections, III. Codimension 2,” <i>Russian Mathematical Surveys</i>, 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.” <i>Russian Mathematical Surveys</i>, vol. 75, no. 6, IOP Publishing,
    2020, pp. 1156–58, doi:<a href="https://doi.org/10.1070/RM9943">10.1070/RM9943</a>.
  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: '610'
abstract:
- lang: eng
  text: 'The fact that the complete graph K5 does not embed in the plane has been
    generalized in two independent directions. On the one hand, the solution of the
    classical Heawood problem for graphs on surfaces established that the complete
    graph Kn embeds in a closed surface M (other than the Klein bottle) if and only
    if (n−3)(n−4) ≤ 6b1(M), where b1(M) is the first Z2-Betti number of M. On the
    other hand, van Kampen and Flores proved that the k-skeleton of the n-dimensional
    simplex (the higher-dimensional analogue of Kn+1) embeds in R2k if and only if
    n ≤ 2k + 1. Two decades ago, Kühnel conjectured that the k-skeleton of the n-simplex
    embeds in a compact, (k − 1)-connected 2k-manifold with kth Z2-Betti number bk
    only if the following generalized Heawood inequality holds: (k+1 n−k−1) ≤ (k+1
    2k+1)bk. This is a common generalization of the case of graphs on surfaces as
    well as the van Kampen–Flores theorem. In the spirit of Kühnel’s conjecture, we
    prove that if the k-skeleton of the n-simplex embeds in a compact 2k-manifold
    with kth Z2-Betti number bk, then n ≤ 2bk(k 2k+2)+2k+4. This bound is weaker than
    the generalized Heawood inequality, but does not require the assumption that M
    is (k−1)-connected. Our results generalize to maps without q-covered points, in
    the spirit of Tverberg’s theorem, for q a prime power. Our proof uses a result
    of Volovikov about maps that satisfy a certain homological triviality condition.'
acknowledgement: The work by Z. P. was partially supported by the Israel Science Foundation
  grant ISF-768/12. The work by Z. P. and M. T. was partially supported by the project
  CE-ITI (GACR P202/12/G061) of the Czech Science Foundation and by the ERC Advanced
  Grant No. 267165. Part of the research work of M.T. was conducted at IST Austria,
  supported by an IST Fellowship. The research of P. P. was supported by the ERC Advanced
  grant no. 320924. The work by I. M. and U. W. was supported by the Swiss National
  Science Foundation (grants SNSF-200020-138230 and SNSF-PP00P2-138948). The collaboration
  between U. W. and X. G. was partially supported by the LabEx Bézout (ANR-10-LABX-58).
author:
- first_name: Xavier
  full_name: Goaoc, Xavier
  last_name: Goaoc
- first_name: Isaac
  full_name: Mabillard, Isaac
  id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
  last_name: Mabillard
- 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, Mabillard I, Paták P, Patakova Z, Tancer M, Wagner U. On generalized
    Heawood inequalities for manifolds: A van Kampen–Flores type nonembeddability
    result. <i>Israel Journal of Mathematics</i>. 2017;222(2):841-866. doi:<a href="https://doi.org/10.1007/s11856-017-1607-7">10.1007/s11856-017-1607-7</a>'
  apa: 'Goaoc, X., Mabillard, I., Paták, P., Patakova, Z., Tancer, M., &#38; Wagner,
    U. (2017). On generalized Heawood inequalities for manifolds: A van Kampen–Flores
    type nonembeddability result. <i>Israel Journal of Mathematics</i>. Springer.
    <a href="https://doi.org/10.1007/s11856-017-1607-7">https://doi.org/10.1007/s11856-017-1607-7</a>'
  chicago: 'Goaoc, Xavier, Isaac Mabillard, Pavel Paták, Zuzana Patakova, Martin Tancer,
    and Uli Wagner. “On Generalized Heawood Inequalities for Manifolds: A van Kampen–Flores
    Type Nonembeddability Result.” <i>Israel Journal of Mathematics</i>. Springer,
    2017. <a href="https://doi.org/10.1007/s11856-017-1607-7">https://doi.org/10.1007/s11856-017-1607-7</a>.'
  ieee: 'X. Goaoc, I. Mabillard, P. Paták, Z. Patakova, M. Tancer, and U. Wagner,
    “On generalized Heawood inequalities for manifolds: A van Kampen–Flores type nonembeddability
    result,” <i>Israel Journal of Mathematics</i>, vol. 222, no. 2. Springer, pp.
    841–866, 2017.'
  ista: 'Goaoc X, Mabillard I, Paták P, Patakova Z, Tancer M, Wagner U. 2017. On generalized
    Heawood inequalities for manifolds: A van Kampen–Flores type nonembeddability
    result. Israel Journal of Mathematics. 222(2), 841–866.'
  mla: 'Goaoc, Xavier, et al. “On Generalized Heawood Inequalities for Manifolds:
    A van Kampen–Flores Type Nonembeddability Result.” <i>Israel Journal of Mathematics</i>,
    vol. 222, no. 2, Springer, 2017, pp. 841–66, doi:<a href="https://doi.org/10.1007/s11856-017-1607-7">10.1007/s11856-017-1607-7</a>.'
  short: X. Goaoc, I. Mabillard, P. Paták, Z. Patakova, M. Tancer, U. Wagner, Israel
    Journal of Mathematics 222 (2017) 841–866.
date_created: 2018-12-11T11:47:29Z
date_published: 2017-10-01T00:00:00Z
date_updated: 2023-02-23T10:02:13Z
day: '01'
department:
- _id: UlWa
doi: 10.1007/s11856-017-1607-7
ec_funded: 1
intvolume: '       222'
issue: '2'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/1610.09063
month: '10'
oa: 1
oa_version: Preprint
page: 841 - 866
project:
- _id: 25681D80-B435-11E9-9278-68D0E5697425
  call_identifier: FP7
  grant_number: '291734'
  name: International IST Postdoc Fellowship Programme
publication: Israel Journal of Mathematics
publication_status: published
publisher: Springer
publist_id: '7194'
quality_controlled: '1'
related_material:
  record:
  - id: '1511'
    relation: earlier_version
    status: public
scopus_import: 1
status: public
title: 'On generalized Heawood inequalities for manifolds: A van Kampen–Flores type
  nonembeddability result'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 222
year: '2017'
...
---
_id: '1123'
abstract:
- lang: eng
  text: "Motivated by topological Tverberg-type problems  in topological combinatorics
    and by classical\r\nresults about embeddings (maps without double points), we
    study the question whether a finite\r\nsimplicial complex K  can be mapped into
    Rd  without triple, quadruple, or, more generally, r-fold points  (image points
    with at least r  distinct preimages), for a given multiplicity r ≤ 2. In particular,
    we are interested in maps f : K → Rd  that have no global r -fold intersection
    points, i.e., no r -fold points with preimages in r pairwise disjoint  simplices
    of K , and we seek necessary and sufficient conditions for the existence of such
    maps.\r\n\r\nWe present higher-multiplicity analogues of several classical results
    for embeddings, in particular of the completeness of the Van Kampen obstruction
    \ for embeddability of k -dimensional\r\ncomplexes into R2k , k ≥ 3. Speciffically,
    we show that under suitable restrictions on the dimensions(viz., if dimK  = (r
    ≥ 1)k  and d  = rk \\ for some k ≥ 3), a well-known deleted product criterion
    (DPC ) is not only necessary but also sufficient for the existence of maps without
    global r -fold points. Our main technical tool is a higher-multiplicity version
    of the classical Whitney trick , by which pairs of isolated r -fold points of
    opposite sign  can be eliminated by local modiffications of the map, assuming
    codimension d – dimK ≥ 3.\r\n\r\nAn important guiding idea for our work was that
    suffciency of the DPC, together with an old\r\nresult of Özaydin's on the existence
    of equivariant maps, might yield an approach to disproving the remaining open
    cases of the the long-standing topological Tverberg conjecture , i.e., to construct
    maps from the N -simplex σN  to Rd  without r-Tverberg points when r not a prime
    power  and\r\nN  = (d  + 1)(r – 1). Unfortunately, our proof of the sufficiency
    of the DPC requires codimension d – dimK ≥ 3, which is not satisfied for K  =
    σN .\r\n\r\nIn 2015, Frick [16] found a very elegant way to overcome this \\codimension
    3 obstacle&quot; and\r\nto construct the first counterexamples to the topological
    Tverberg conjecture for all parameters(d; r ) with d ≥ 3r  + 1 and r  not a prime
    power, by a reduction1  to a suitable lower-dimensional skeleton, for which the
    codimension 3 restriction is satisfied and maps without r -Tverberg points exist
    by Özaydin's result and sufficiency of the DPC.\r\n\r\nIn this thesis, we present
    a different construction (which does not use the constraint method) that yields
    counterexamples for d ≥ 3r , r  not a prime power.     "
acknowledgement: "Foremost, I would like to thank Uli Wagner for introducing me to
  the exciting interface between\r\ntopology and combinatorics, and for our subsequent
  years of fruitful collaboration.\r\nIn our creative endeavors to eliminate intersection
  points, we had the chance to be joined later\r\nby Sergey Avvakumov and Arkadiy
  Skopenkov, which led us to new surprises in dimension 12.\r\nMy stay at EPFL and
  IST Austria was made very agreeable thanks to all these wonderful\r\npeople: Cyril
  Becker, Marek Filakovsky, Peter Franek, Radoslav Fulek, Peter Gazi, Kristof Huszar,\r\nMarek
  Krcal, Zuzana Masarova, Arnaud de Mesmay, Filip Moric, Michal Rybar, Martin Tancer,\r\nand
  Stephan Zhechev.\r\nFinally, I would like to thank my thesis committee Herbert Edelsbrunner
  and Roman Karasev\r\nfor their careful reading of the present manuscript and for
  the many improvements they suggested."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Isaac
  full_name: Mabillard, Isaac
  id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
  last_name: Mabillard
citation:
  ama: 'Mabillard I. Eliminating higher-multiplicity intersections: an r-fold Whitney
    trick for the topological Tverberg conjecture. 2016.'
  apa: 'Mabillard, I. (2016). <i>Eliminating higher-multiplicity intersections: an
    r-fold Whitney trick for the topological Tverberg conjecture</i>. Institute of
    Science and Technology Austria.'
  chicago: 'Mabillard, Isaac. “Eliminating Higher-Multiplicity Intersections: An r-Fold
    Whitney Trick for the Topological Tverberg Conjecture.” Institute of Science and
    Technology Austria, 2016.'
  ieee: 'I. Mabillard, “Eliminating higher-multiplicity intersections: an r-fold Whitney
    trick for the topological Tverberg conjecture,” Institute of Science and Technology
    Austria, 2016.'
  ista: 'Mabillard I. 2016. Eliminating higher-multiplicity intersections: an r-fold
    Whitney trick for the topological Tverberg conjecture. Institute of Science and
    Technology Austria.'
  mla: 'Mabillard, Isaac. <i>Eliminating Higher-Multiplicity Intersections: An r-Fold
    Whitney Trick for the Topological Tverberg Conjecture</i>. Institute of Science
    and Technology Austria, 2016.'
  short: 'I. Mabillard, Eliminating Higher-Multiplicity Intersections: An r-Fold Whitney
    Trick for the Topological Tverberg Conjecture, Institute of Science and Technology
    Austria, 2016.'
date_created: 2018-12-11T11:50:16Z
date_published: 2016-08-01T00:00:00Z
date_updated: 2023-09-07T11:56:28Z
day: '01'
ddc:
- '500'
degree_awarded: PhD
department:
- _id: UlWa
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publication_identifier:
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publication_status: published
publisher: Institute of Science and Technology Austria
publist_id: '6237'
related_material:
  record:
  - id: '2159'
    relation: part_of_dissertation
    status: public
status: public
supervisor:
- first_name: Uli
  full_name: Wagner, Uli
  id: 36690CA2-F248-11E8-B48F-1D18A9856A87
  last_name: Wagner
  orcid: 0000-0002-1494-0568
title: 'Eliminating higher-multiplicity intersections: an r-fold Whitney trick for
  the topological Tverberg conjecture'
type: dissertation
user_id: c635000d-4b10-11ee-a964-aac5a93f6ac1
year: '2016'
...
---
_id: '1381'
abstract:
- lang: eng
  text: 'Motivated by Tverberg-type problems in topological combinatorics and by classical
    results about embeddings (maps without double points), we study the question whether
    a finite simplicial complex K can be mapped into double-struck Rd without higher-multiplicity
    intersections. We focus on conditions for the existence of almost r-embeddings,
    i.e., maps f : K → double-struck Rd such that f(σ1) ∩ ⋯ ∩ f(σr) = ∅ whenever σ1,
    ..., σr are pairwise disjoint simplices of K. Generalizing the classical Haefliger-Weber
    embeddability criterion, we show that a well-known necessary deleted product condition
    for the existence of almost r-embeddings is sufficient in a suitable r-metastable
    range of dimensions: If rd ≥ (r + 1) dim K + 3, then there exists an almost r-embedding
    K → double-struck Rd if and only if there exists an equivariant map (K)Δ r → Sr
    Sd(r-1)-1, where (K)Δ r is the deleted r-fold product of K, the target Sd(r-1)-1
    is the sphere of dimension d(r - 1) - 1, and Sr is the symmetric group. This significantly
    extends one of the main results of our previous paper (which treated the special
    case where d = rk and dim K = (r - 1)k for some k ≥ 3), and settles an open question
    raised there.'
alternative_title:
- LIPIcs
author:
- first_name: Isaac
  full_name: Mabillard, Isaac
  id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
  last_name: Mabillard
- first_name: Uli
  full_name: Wagner, Uli
  id: 36690CA2-F248-11E8-B48F-1D18A9856A87
  last_name: Wagner
  orcid: 0000-0002-1494-0568
citation:
  ama: 'Mabillard I, Wagner U. Eliminating higher-multiplicity intersections, II.
    The deleted product criterion in the r-metastable range. In: Vol 51. Schloss Dagstuhl-
    Leibniz-Zentrum fur Informatik GmbH; 2016:51.1-51.12. doi:<a href="https://doi.org/10.4230/LIPIcs.SoCG.2016.51">10.4230/LIPIcs.SoCG.2016.51</a>'
  apa: 'Mabillard, I., &#38; Wagner, U. (2016). Eliminating higher-multiplicity intersections,
    II. The deleted product criterion in the r-metastable range (Vol. 51, p. 51.1-51.12).
    Presented at the SoCG: Symposium on Computational Geometry, Medford, MA, USA:
    Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH. <a href="https://doi.org/10.4230/LIPIcs.SoCG.2016.51">https://doi.org/10.4230/LIPIcs.SoCG.2016.51</a>'
  chicago: Mabillard, Isaac, and Uli Wagner. “Eliminating Higher-Multiplicity Intersections,
    II. The Deleted Product Criterion in the r-Metastable Range,” 51:51.1-51.12. Schloss
    Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, 2016. <a href="https://doi.org/10.4230/LIPIcs.SoCG.2016.51">https://doi.org/10.4230/LIPIcs.SoCG.2016.51</a>.
  ieee: 'I. Mabillard and U. Wagner, “Eliminating higher-multiplicity intersections,
    II. The deleted product criterion in the r-metastable range,” presented at the
    SoCG: Symposium on Computational Geometry, Medford, MA, USA, 2016, vol. 51, p.
    51.1-51.12.'
  ista: 'Mabillard I, Wagner U. 2016. Eliminating higher-multiplicity intersections,
    II. The deleted product criterion in the r-metastable range. SoCG: Symposium on
    Computational Geometry, LIPIcs, vol. 51, 51.1-51.12.'
  mla: Mabillard, Isaac, and Uli Wagner. <i>Eliminating Higher-Multiplicity Intersections,
    II. The Deleted Product Criterion in the r-Metastable Range</i>. Vol. 51, Schloss
    Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, 2016, p. 51.1-51.12, doi:<a href="https://doi.org/10.4230/LIPIcs.SoCG.2016.51">10.4230/LIPIcs.SoCG.2016.51</a>.
  short: I. Mabillard, U. Wagner, in:, Schloss Dagstuhl- Leibniz-Zentrum fur Informatik
    GmbH, 2016, p. 51.1-51.12.
conference:
  end_date: 2016-06-17
  location: Medford, MA, USA
  name: 'SoCG: Symposium on Computational Geometry'
  start_date: 2016-06-14
date_created: 2018-12-11T11:51:41Z
date_published: 2016-06-01T00:00:00Z
date_updated: 2021-01-12T06:50:17Z
day: '01'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SoCG.2016.51
file:
- access_level: open_access
  checksum: 92c0c3735fe908f8ded6e484005cb3b1
  content_type: application/pdf
  creator: system
  date_created: 2018-12-12T10:10:06Z
  date_updated: 2020-07-14T12:44:47Z
  file_id: '4791'
  file_name: IST-2016-621-v1+1_LIPIcs-SoCG-2016-51.pdf
  file_size: 622969
  relation: main_file
file_date_updated: 2020-07-14T12:44:47Z
has_accepted_license: '1'
intvolume: '        51'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
page: 51.1 - 51.12
project:
- _id: 25FA3206-B435-11E9-9278-68D0E5697425
  grant_number: PP00P2_138948
  name: 'Embeddings in Higher Dimensions: Algorithms and Combinatorics'
publication_status: published
publisher: Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH
publist_id: '5830'
pubrep_id: '621'
quality_controlled: '1'
scopus_import: 1
status: public
title: Eliminating higher-multiplicity intersections, II. The deleted product criterion
  in the r-metastable range
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: 3E5EF7F0-F248-11E8-B48F-1D18A9856A87
volume: 51
year: '2016'
...
---
_id: '8183'
abstract:
- lang: eng
  text: "We study conditions under which a finite simplicial complex $K$ can be mapped
    to $\\mathbb R^d$ without higher-multiplicity intersections. An almost $r$-embedding
    is a map $f: K\\to \\mathbb R^d$ such that the images of any $r$\r\npairwise disjoint
    simplices of $K$ do not have a common point. We show that if $r$ is not a prime
    power and $d\\geq 2r+1$, then there is a counterexample to the topological Tverberg
    conjecture, i.e., there is an almost $r$-embedding of\r\nthe $(d+1)(r-1)$-simplex
    in $\\mathbb R^d$. This improves on previous constructions of counterexamples
    (for $d\\geq 3r$) based on a series of papers by M. \\\"Ozaydin, M. Gromov, P.
    Blagojevi\\'c, F. Frick, G. Ziegler, and the second and fourth present authors.
    The counterexamples are obtained by proving the following algebraic criterion
    in codimension 2: If $r\\ge3$ and if $K$ is a finite $2(r-1)$-complex then there
    exists an almost $r$-embedding $K\\to \\mathbb R^{2r}$ if and only if there exists
    a general position PL map $f:K\\to \\mathbb R^{2r}$ 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 cohomological obstructions or equivariant
    maps, and extends an analogous codimension 3 criterion by the second and fourth
    authors. As another application we classify ornaments $f:S^3 \\sqcup S^3\\sqcup
    S^3\\to \\mathbb R^5$ up to ornament\r\nconcordance. It 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: We would like to thank A. Klyachko, V. Krushkal, S. Melikhov, M.
  Tancer, P. Teichner and anonymous referees for helpful discussions.
article_number: '1511.03501'
article_processing_charge: No
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: A.
  full_name: Skopenkov, A.
  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 A, Wagner U. Eliminating higher-multiplicity
    intersections, III. Codimension 2. <i>arXiv</i>.
  apa: Avvakumov, S., Mabillard, I., Skopenkov, A., &#38; Wagner, U. (n.d.). Eliminating
    higher-multiplicity intersections, III. Codimension 2. <i>arXiv</i>.
  chicago: Avvakumov, Sergey, Isaac Mabillard, A. Skopenkov, and Uli Wagner. “Eliminating
    Higher-Multiplicity Intersections, III. Codimension 2.” <i>ArXiv</i>, n.d.
  ieee: S. Avvakumov, I. Mabillard, A. Skopenkov, and U. Wagner, “Eliminating higher-multiplicity
    intersections, III. Codimension 2,” <i>arXiv</i>. .
  ista: Avvakumov S, Mabillard I, Skopenkov A, Wagner U. Eliminating higher-multiplicity
    intersections, III. Codimension 2. arXiv, 1511.03501.
  mla: Avvakumov, Sergey, et al. “Eliminating Higher-Multiplicity Intersections, III.
    Codimension 2.” <i>ArXiv</i>, 1511.03501.
  short: S. Avvakumov, I. Mabillard, A. Skopenkov, U. Wagner, ArXiv (n.d.).
date_created: 2020-07-30T10:45:19Z
date_published: 2015-11-15T00:00:00Z
date_updated: 2023-09-07T13:12:17Z
day: '15'
department:
- _id: UlWa
external_id:
  arxiv:
  - '1511.03501'
language:
- iso: eng
main_file_link:
- open_access: '1'
  url: https://arxiv.org/abs/1511.03501
month: '11'
oa: 1
oa_version: Preprint
publication: arXiv
publication_status: submitted
related_material:
  record:
  - id: '9308'
    relation: later_version
    status: public
  - id: '10220'
    relation: later_version
    status: public
  - id: '8156'
    relation: dissertation_contains
    status: public
status: public
title: Eliminating higher-multiplicity intersections, III. Codimension 2
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2015'
...
---
_id: '1511'
abstract:
- lang: eng
  text: 'The fact that the complete graph K_5 does not embed in the plane has been
    generalized in two independent directions. On the one hand, the solution of the
    classical Heawood problem for graphs on surfaces established that the complete
    graph K_n embeds in a closed surface M if and only if (n-3)(n-4) is at most 6b_1(M),
    where b_1(M) is the first Z_2-Betti number of M. On the other hand, Van Kampen
    and Flores proved that the k-skeleton of the n-dimensional simplex (the higher-dimensional
    analogue of K_{n+1}) embeds in R^{2k} if and only if n is less or equal to 2k+2.
    Two decades ago, Kuhnel conjectured that the k-skeleton of the n-simplex embeds
    in a compact, (k-1)-connected 2k-manifold with kth Z_2-Betti number b_k only if
    the following generalized Heawood inequality holds: binom{n-k-1}{k+1} is at most
    binom{2k+1}{k+1} b_k. This is a common generalization of the case of graphs on
    surfaces as well as the Van Kampen--Flores theorem. In the spirit of Kuhnel''s
    conjecture, we prove that if the k-skeleton of the n-simplex embeds in a 2k-manifold
    with kth Z_2-Betti number b_k, then n is at most 2b_k binom{2k+2}{k} + 2k + 5.
    This bound is weaker than the generalized Heawood inequality, but does not require
    the assumption that M is (k-1)-connected. Our proof uses a result of Volovikov
    about maps that satisfy a certain homological triviality condition.'
acknowledgement: "The work by Z. P. was partially supported by the Charles University
  Grant SVV-2014-260103. The\r\nwork by Z. P. and M. T. was partially supported by
  the project CE-ITI (GACR P202/12/G061) of\r\nthe Czech Science Foundation and by
  the ERC Advanced Grant No. 267165. Part of the research\r\nwork of M. T. was conducted
  at IST Austria, supported by an IST Fellowship. The work by U.W.\r\nwas partially
  supported by the Swiss National Science Foundation (grants SNSF-200020-138230 and\r\nSNSF-PP00P2-138948)."
alternative_title:
- LIPIcs
author:
- first_name: Xavier
  full_name: Goaoc, Xavier
  last_name: Goaoc
- first_name: Isaac
  full_name: Mabillard, Isaac
  id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
  last_name: Mabillard
- 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, Mabillard I, Paták P, Patakova Z, Tancer M, Wagner U. On generalized
    Heawood inequalities for manifolds: A Van Kampen–Flores-type nonembeddability
    result. In: Vol 34. Schloss Dagstuhl - Leibniz-Zentrum für Informatik; 2015:476-490.
    doi:<a href="https://doi.org/10.4230/LIPIcs.SOCG.2015.476">10.4230/LIPIcs.SOCG.2015.476</a>'
  apa: 'Goaoc, X., Mabillard, I., Paták, P., Patakova, Z., Tancer, M., &#38; Wagner,
    U. (2015). On generalized Heawood inequalities for manifolds: A Van Kampen–Flores-type
    nonembeddability result (Vol. 34, pp. 476–490). Presented at the SoCG: Symposium
    on Computational Geometry, Eindhoven, Netherlands: Schloss Dagstuhl - Leibniz-Zentrum
    für Informatik. <a href="https://doi.org/10.4230/LIPIcs.SOCG.2015.476">https://doi.org/10.4230/LIPIcs.SOCG.2015.476</a>'
  chicago: 'Goaoc, Xavier, Isaac Mabillard, Pavel Paták, Zuzana Patakova, Martin Tancer,
    and Uli Wagner. “On Generalized Heawood Inequalities for Manifolds: A Van Kampen–Flores-Type
    Nonembeddability Result,” 34:476–90. Schloss Dagstuhl - Leibniz-Zentrum für Informatik,
    2015. <a href="https://doi.org/10.4230/LIPIcs.SOCG.2015.476">https://doi.org/10.4230/LIPIcs.SOCG.2015.476</a>.'
  ieee: 'X. Goaoc, I. Mabillard, P. Paták, Z. Patakova, M. Tancer, and U. Wagner,
    “On generalized Heawood inequalities for manifolds: A Van Kampen–Flores-type nonembeddability
    result,” presented at the SoCG: Symposium on Computational Geometry, Eindhoven,
    Netherlands, 2015, vol. 34, pp. 476–490.'
  ista: 'Goaoc X, Mabillard I, Paták P, Patakova Z, Tancer M, Wagner U. 2015. On generalized
    Heawood inequalities for manifolds: A Van Kampen–Flores-type nonembeddability
    result. SoCG: Symposium on Computational Geometry, LIPIcs, vol. 34, 476–490.'
  mla: 'Goaoc, Xavier, et al. <i>On Generalized Heawood Inequalities for Manifolds:
    A Van Kampen–Flores-Type Nonembeddability Result</i>. Vol. 34, Schloss Dagstuhl
    - Leibniz-Zentrum für Informatik, 2015, pp. 476–90, doi:<a href="https://doi.org/10.4230/LIPIcs.SOCG.2015.476">10.4230/LIPIcs.SOCG.2015.476</a>.'
  short: X. Goaoc, I. Mabillard, P. Paták, Z. Patakova, M. Tancer, U. Wagner, in:,
    Schloss Dagstuhl - Leibniz-Zentrum für Informatik, 2015, pp. 476–490.
conference:
  end_date: 2015-06-25
  location: Eindhoven, Netherlands
  name: 'SoCG: Symposium on Computational Geometry'
  start_date: 2015-06-22
date_created: 2018-12-11T11:52:27Z
date_published: 2015-06-11T00:00:00Z
date_updated: 2023-02-23T12:38:00Z
day: '11'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.4230/LIPIcs.SOCG.2015.476
ec_funded: 1
file:
- access_level: open_access
  checksum: 0945811875351796324189312ca29e9e
  content_type: application/pdf
  creator: system
  date_created: 2018-12-12T10:11:18Z
  date_updated: 2020-07-14T12:44:59Z
  file_id: '4871'
  file_name: IST-2016-502-v1+1_42.pdf
  file_size: 636735
  relation: main_file
file_date_updated: 2020-07-14T12:44:59Z
has_accepted_license: '1'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
page: 476 - 490
project:
- _id: 25681D80-B435-11E9-9278-68D0E5697425
  call_identifier: FP7
  grant_number: '291734'
  name: International IST Postdoc Fellowship Programme
publication_status: published
publisher: Schloss Dagstuhl - Leibniz-Zentrum für Informatik
publist_id: '5666'
pubrep_id: '502'
quality_controlled: '1'
related_material:
  record:
  - id: '610'
    relation: later_version
    status: public
scopus_import: 1
status: public
title: 'On generalized Heawood inequalities for manifolds: A Van Kampen–Flores-type
  nonembeddability result'
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: '34 '
year: '2015'
...
---
_id: '2159'
abstract:
- lang: eng
  text: 'Motivated by topological Tverberg-type problems, we consider multiple (double,
    triple, and higher multiplicity) selfintersection points of maps from finite simplicial
    complexes (compact polyhedra) into ℝd and study conditions under which such multiple
    points can be eliminated. The most classical case is that of embeddings (i.e.,
    maps without double points) of a κ-dimensional complex K into ℝ2κ. For this problem,
    the work of van Kampen, Shapiro, and Wu provides an efficiently testable necessary
    condition for embeddability (namely, vanishing of the van Kampen ob-struction).
    For κ ≥ 3, the condition is also sufficient, and yields a polynomial-time algorithm
    for deciding embeddability: One starts with an arbitrary map f : K→ℝ2κ, which
    generically has finitely many double points; if k ≥ 3 and if the obstruction vanishes
    then one can successively remove these double points by local modifications of
    the map f. One of the main tools is the famous Whitney trick that permits eliminating
    pairs of double points of opposite intersection sign. We are interested in generalizing
    this approach to intersection points of higher multiplicity. We call a point y
    2 ℝd an r-fold Tverberg point of a map f : Kκ →ℝd if y lies in the intersection
    f(σ1)∩. ∩f(σr) of the images of r pairwise disjoint simplices of K. The analogue
    of (non-)embeddability that we study is the problem Tverbergκ r→d: Given a κ-dimensional
    complex K, does it satisfy a Tverberg-type theorem with parameters r and d, i.e.,
    does every map f : K κ → ℝd have an r-fold Tverberg point? Here, we show that
    for fixed r, κ and d of the form d = rm and k = (r-1)m, m ≥ 3, there is a polynomial-time
    algorithm for deciding this (based on the vanishing of a cohomological obstruction,
    as in the case of embeddings). Our main tool is an r-fold analogue of the Whitney
    trick: Given r pairwise disjoint simplices of K such that the intersection of
    their images contains two r-fold Tverberg points y+ and y- of opposite intersection
    sign, we can eliminate y+ and y- by a local isotopy of f. In a subsequent paper,
    we plan to develop this further and present a generalization of the classical
    Haeiger-Weber Theorem (which yields a necessary and sufficient condition for embeddability
    of κ-complexes into ℝd for a wider range of dimensions) to intersection points
    of higher multiplicity.'
acknowledgement: Swiss National Science Foundation (Project SNSF-PP00P2-138948)
author:
- first_name: Isaac
  full_name: Mabillard, Isaac
  id: 32BF9DAA-F248-11E8-B48F-1D18A9856A87
  last_name: Mabillard
- first_name: Uli
  full_name: Wagner, Uli
  id: 36690CA2-F248-11E8-B48F-1D18A9856A87
  last_name: Wagner
  orcid: 0000-0002-1494-0568
citation:
  ama: 'Mabillard I, Wagner U. Eliminating Tverberg points, I. An analogue of the
    Whitney trick. In: <i>Proceedings of the Annual Symposium on Computational Geometry</i>.
    ACM; 2014:171-180. doi:<a href="https://doi.org/10.1145/2582112.2582134">10.1145/2582112.2582134</a>'
  apa: 'Mabillard, I., &#38; Wagner, U. (2014). Eliminating Tverberg points, I. An
    analogue of the Whitney trick. In <i>Proceedings of the Annual Symposium on Computational
    Geometry</i> (pp. 171–180). Kyoto, Japan: ACM. <a href="https://doi.org/10.1145/2582112.2582134">https://doi.org/10.1145/2582112.2582134</a>'
  chicago: Mabillard, Isaac, and Uli Wagner. “Eliminating Tverberg Points, I. An Analogue
    of the Whitney Trick.” In <i>Proceedings of the Annual Symposium on Computational
    Geometry</i>, 171–80. ACM, 2014. <a href="https://doi.org/10.1145/2582112.2582134">https://doi.org/10.1145/2582112.2582134</a>.
  ieee: I. Mabillard and U. Wagner, “Eliminating Tverberg points, I. An analogue of
    the Whitney trick,” in <i>Proceedings of the Annual Symposium on Computational
    Geometry</i>, Kyoto, Japan, 2014, pp. 171–180.
  ista: 'Mabillard I, Wagner U. 2014. Eliminating Tverberg points, I. An analogue
    of the Whitney trick. Proceedings of the Annual Symposium on Computational Geometry.
    SoCG: Symposium on Computational Geometry, 171–180.'
  mla: Mabillard, Isaac, and Uli Wagner. “Eliminating Tverberg Points, I. An Analogue
    of the Whitney Trick.” <i>Proceedings of the Annual Symposium on Computational
    Geometry</i>, ACM, 2014, pp. 171–80, doi:<a href="https://doi.org/10.1145/2582112.2582134">10.1145/2582112.2582134</a>.
  short: I. Mabillard, U. Wagner, in:, Proceedings of the Annual Symposium on Computational
    Geometry, ACM, 2014, pp. 171–180.
conference:
  end_date: 2014-06-11
  location: Kyoto, Japan
  name: 'SoCG: Symposium on Computational Geometry'
  start_date: 2014-06-08
date_created: 2018-12-11T11:56:03Z
date_published: 2014-06-08T00:00:00Z
date_updated: 2023-09-07T11:56:27Z
day: '08'
ddc:
- '510'
department:
- _id: UlWa
doi: 10.1145/2582112.2582134
file:
- access_level: open_access
  checksum: 2aae223fee8ffeaf57bbabd8d92b6a2c
  content_type: application/pdf
  creator: system
  date_created: 2018-12-12T10:09:12Z
  date_updated: 2020-07-14T12:45:30Z
  file_id: '4735'
  file_name: IST-2016-534-v1+1_Eliminating_Tverberg_points_I._An_analogue_of_the_Whitney_trick.pdf
  file_size: 914396
  relation: main_file
file_date_updated: 2020-07-14T12:45:30Z
has_accepted_license: '1'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Submitted Version
page: 171 - 180
publication: Proceedings of the Annual Symposium on Computational Geometry
publication_status: published
publisher: ACM
publist_id: '4847'
pubrep_id: '534'
quality_controlled: '1'
related_material:
  record:
  - id: '1123'
    relation: dissertation_contains
    status: public
scopus_import: 1
status: public
title: Eliminating Tverberg points, I. An analogue of the Whitney trick
type: conference
user_id: 4435EBFC-F248-11E8-B48F-1D18A9856A87
year: '2014'
...
