@unpublished{8547, abstract = {The cerebral cortex contains multiple hierarchically organized areas with distinctive cytoarchitectonical patterns, but the cellular mechanisms underlying the emergence of this diversity remain unclear. Here, we have quantitatively investigated the neuronal output of individual progenitor cells in the ventricular zone of the developing mouse neocortex using a combination of methods that together circumvent the biases and limitations of individual approaches. We found that individual cortical progenitor cells show a high degree of stochasticity and generate pyramidal cell lineages that adopt a wide range of laminar configurations. Mathematical modelling these lineage data suggests that a small number of progenitor cell populations, each generating pyramidal cells following different stochastic developmental programs, suffice to generate the heterogenous complement of pyramidal cell lineages that collectively build the complex cytoarchitecture of the neocortex.}, author = {Llorca, Alfredo and Ciceri, Gabriele and Beattie, Robert J and Wong, Fong K. and Diana, Giovanni and Serafeimidou, Eleni and Fernández-Otero, Marian and Streicher, Carmen and Arnold, Sebastian J. and Meyer, Martin and Hippenmeyer, Simon and Maravall, Miguel and Marín, Oscar}, booktitle = {bioRxiv}, publisher = {Cold Spring Harbor Laboratory}, title = {{Heterogeneous progenitor cell behaviors underlie the assembly of neocortical cytoarchitecture}}, doi = {10.1101/494088}, year = {2018}, } @inbook{86, abstract = {Responsiveness—the requirement that every request to a system be eventually handled—is one of the fundamental liveness properties of a reactive system. Average response time is a quantitative measure for the responsiveness requirement used commonly in performance evaluation. We show how average response time can be computed on state-transition graphs, on Markov chains, and on game graphs. In all three cases, we give polynomial-time algorithms.}, author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Otop, Jan}, booktitle = {Principles of Modeling}, editor = {Lohstroh, Marten and Derler, Patricia and Sirjani, Marjan}, pages = {143 -- 161}, publisher = {Springer}, title = {{Computing average response time}}, doi = {10.1007/978-3-319-95246-8_9}, volume = {10760}, year = {2018}, } @article{8618, abstract = {The reversibly switchable fluorescent proteins (RSFPs) commonly used for RESOLFT nanoscopy have been developed from fluorescent proteins of the GFP superfamily. These proteins are bright, but exhibit several drawbacks such as relatively large size, oxygen-dependence, sensitivity to low pH, and limited switching speed. Therefore, RSFPs from other origins with improved properties need to be explored. Here, we report the development of two RSFPs based on the LOV domain of the photoreceptor protein YtvA from Bacillus subtilis. LOV domains obtain their fluorescence by association with the abundant cellular cofactor flavin mononucleotide (FMN). Under illumination with blue and ultraviolet light, they undergo a photocycle, making these proteins inherently photoswitchable. Our first improved variant, rsLOV1, can be used for RESOLFT imaging, whereas rsLOV2 proved useful for STED nanoscopy of living cells with a resolution of down to 50 nm. In addition to their smaller size compared to GFP-related proteins (17 kDa instead of 27 kDa) and their usability at low pH, rsLOV1 and rsLOV2 exhibit faster switching kinetics, switching on and off 3 times faster than rsEGFP2, the fastest-switching RSFP reported to date. Therefore, LOV-domain-based RSFPs have potential for applications where the switching speed of GFP-based proteins is limiting.}, author = {Gregor, Carola and Sidenstein, Sven C. and Andresen, Martin and Sahl, Steffen J. and Danzl, Johann G and Hell, Stefan W.}, issn = {2045-2322}, journal = {Scientific Reports}, keywords = {Multidisciplinary}, publisher = {Springer Nature}, title = {{Novel reversibly switchable fluorescent proteins for RESOLFT and STED nanoscopy engineered from the bacterial photoreceptor YtvA}}, doi = {10.1038/s41598-018-19947-1}, volume = {8}, year = {2018}, } @article{87, abstract = {Using the geodesic distance on the n-dimensional sphere, we study the expected radius function of the Delaunay mosaic of a random set of points. Specifically, we consider the partition of the mosaic into intervals of the radius function and determine the expected number of intervals whose radii are less than or equal to a given threshold. We find that the expectations are essentially the same as for the Poisson–Delaunay mosaic in n-dimensional Euclidean space. Assuming the points are not contained in a hemisphere, the Delaunay mosaic is isomorphic to the boundary complex of the convex hull in Rn+1, so we also get the expected number of faces of a random inscribed polytope. As proved in Antonelli et al. [Adv. in Appl. Probab. 9–12 (1977–1980)], an orthant section of the n-sphere is isometric to the standard n-simplex equipped with the Fisher information metric. It follows that the latter space has similar stochastic properties as the n-dimensional Euclidean space. Our results are therefore relevant in information geometry and in population genetics.}, author = {Edelsbrunner, Herbert and Nikitenko, Anton}, journal = {Annals of Applied Probability}, number = {5}, pages = {3215 -- 3238}, publisher = {Institute of Mathematical Statistics}, title = {{Random inscribed polytopes have similar radius functions as Poisson-Delaunay mosaics}}, doi = {10.1214/18-AAP1389}, volume = {28}, year = {2018}, } @phdthesis{9, abstract = {Immune cells migrating to the sites of infection navigate through diverse tissue architectures and switch their migratory mechanisms upon demand. However, little is known about systemic regulators that could allow the acquisition of these mechanisms. We performed a genetic screen in Drosophila melanogaster to identify regulators of germband invasion by embryonic macrophages into the confined space between the ectoderm and mesoderm. We have found that bZIP circadian transcription factors (TFs) Kayak (dFos) and Vrille (dNFIL3) have opposite effects on macrophage germband infiltration: Kayak facilitated and Vrille inhibited it. These TFs are enriched in the macrophages during migration and genetically interact to control it. Kayak sets a less coordinated mode of migration of the macrophage group and increases the probability and length of Levy walks. Intriguingly, the motility of kayak mutant macrophages was also strongly affected during initial germband invasion but not along another less confined route. Inhibiting Rho1 signaling within the tail ectoderm partially rescued the Kayak mutant phenotype, strongly suggesting that migrating macrophages have to overcome a barrier imposed by the stiffness of the ectoderm. Also, Kayak appeared to be important for the maintenance of the round cell shape and the rear edge translocation of the macrophages invading the germband. Complementary to this, the cortical actin cytoskeleton of Kayak- deficient macrophages was strongly affected. RNA sequencing revealed the filamin Cheerio and tetraspanin TM4SF to be downstream of Kayak. Chromatin immunoprecipitation and immunostaining revealed that the formin Diaphanous is another downstream target of Kayak. Immunostaining revealed that the formin Diaphanous is another downstream target of Kayak. Indeed, Cheerio, TM4SF and Diaphanous are required within macrophages for germband invasion, and expression of constitutively active Diaphanous in macrophages was able to rescue the kayak mutant phenotype. Moreover, Cher and Diaphanous are also reduced in the macrophages overexpressing Vrille. We hypothesize that Kayak, through its targets, increases actin polymerization and cortical tension in macrophages and thus allows extra force generation necessary for macrophage dissemination and migration through confined stiff tissues, while Vrille counterbalances it.}, author = {Belyaeva, Vera}, issn = {2663-337X}, pages = {96}, publisher = {Institute of Science and Technology Austria}, title = {{Transcriptional regulation of macrophage migration in the Drosophila melanogaster embryo }}, doi = {10.15479/AT:ISTA:th1064}, year = {2018}, } @article{913, abstract = {Coordinated cell polarization in developing tissues is a recurrent theme in multicellular organisms. In plants, a directional distribution of the plant hormone auxin is at the core of many developmental programs. A feedback regulation of auxin on the polarized localization of PIN auxin transporters in individual cells has been proposed as a self-organizing mechanism for coordinated tissue polarization, but the molecular mechanisms linking auxin signalling to PIN-dependent auxin transport remain unknown. We performed a microarray-based approach to find regulators of the auxin-induced PIN relocation in the Arabidopsis thaliana root. We identified a subset of a family of phosphatidylinositol transfer proteins (PITP), the PATELLINs (PATL). Here, we show that PATLs are expressed in partially overlapping cells types in different tissues going through mitosis or initiating differentiation programs. PATLs are plasma membrane-associated proteins accumulated in Arabidopsis embryos, primary roots, lateral root primordia, and developing stomata. Higher order patl mutants display reduced PIN1 repolarization in response to auxin, shorter root apical meristem, and drastic defects in embryo and seedling development. This suggests PATLs redundantly play a crucial role in polarity and patterning in Arabidopsis.}, author = {Tejos, Ricardo and Rodríguez Furlán, Cecilia and Adamowski, Maciek and Sauer, Michael and Norambuena, Lorena and Friml, Jirí}, issn = {00219533}, journal = {Journal of Cell Science}, number = {2}, publisher = {Company of Biologists}, title = {{PATELLINS are regulators of auxin mediated PIN1 relocation and plant development in Arabidopsis thaliana}}, doi = {10.1242/jcs.204198}, volume = {131}, year = {2018}, } @article{9229, author = {Danzl, Johann G}, issn = {2500-2295}, journal = {Opera Medica et Physiologica}, number = {S1}, pages = {11}, publisher = {Lobachevsky State University of Nizhny Novgorod}, title = {{Diffraction-unlimited optical imaging for synaptic physiology}}, doi = {10.20388/omp2018.00s1.001}, volume = {4}, year = {2018}, } @article{691, abstract = {Background: Transport protein particle (TRAPP) is a multisubunit complex that regulates membrane trafficking through the Golgi apparatus. The clinical phenotype associated with mutations in various TRAPP subunits has allowed elucidation of their functions in specific tissues. The role of some subunits in human disease, however, has not been fully established, and their functions remain uncertain. Objective: We aimed to expand the range of neurodevelopmental disorders associated with mutations in TRAPP subunits by exome sequencing of consanguineous families. Methods: Linkage and homozygosity mapping and candidate gene analysis were used to identify homozygous mutations in families. Patient fibroblasts were used to study splicing defect and zebrafish to model the disease. Results: We identified six individuals from three unrelated families with a founder homozygous splice mutation in TRAPPC6B, encoding a core subunit of the complex TRAPP I. Patients manifested a neurodevelopmental disorder characterised by microcephaly, epilepsy and autistic features, and showed splicing defect. Zebrafish trappc6b morphants replicated the human phenotype, displaying decreased head size and neuronal hyperexcitability, leading to a lower seizure threshold. Conclusion: This study provides clinical and functional evidence of the role of TRAPPC6B in brain development and function.}, author = {Marin Valencia, Isaac and Novarino, Gaia and Johansen, Anide and Rosti, Başak and Issa, Mahmoud and Musaev, Damir and Bhat, Gifty and Scott, Eric and Silhavy, Jennifer and Stanley, Valentina and Rosti, Rasim and Gleeson, Jeremy and Imam, Farhad and Zaki, Maha and Gleeson, Joseph}, issn = {0022-2593}, journal = {Journal of Medical Genetics}, number = {1}, pages = {48 -- 54}, publisher = {BMJ Publishing Group}, title = {{A homozygous founder mutation in TRAPPC6B associates with a neurodevelopmental disorder characterised by microcephaly epilepsy and autistic features}}, doi = {10.1136/jmedgenet-2017-104627}, volume = {55}, year = {2018}, } @article{692, abstract = {We consider families of confocal conics and two pencils of Apollonian circles having the same foci. We will show that these families of curves generate trivial 3-webs and find the exact formulas describing them.}, author = {Akopyan, Arseniy}, journal = {Geometriae Dedicata}, number = {1}, pages = {55 -- 64}, publisher = {Springer}, title = {{3-Webs generated by confocal conics and circles}}, doi = {10.1007/s10711-017-0265-6}, volume = {194}, year = {2018}, } @inproceedings{6941, abstract = {Bitcoin has become the most successful cryptocurrency ever deployed, and its most distinctive feature is that it is decentralized. Its underlying protocol (Nakamoto consensus) achieves this by using proof of work, which has the drawback that it causes the consumption of vast amounts of energy to maintain the ledger. Moreover, Bitcoin mining dynamics have become less distributed over time. Towards addressing these issues, we propose SpaceMint, a cryptocurrency based on proofs of space instead of proofs of work. Miners in SpaceMint dedicate disk space rather than computation. We argue that SpaceMint’s design solves or alleviates several of Bitcoin’s issues: most notably, its large energy consumption. SpaceMint also rewards smaller miners fairly according to their contribution to the network, thus incentivizing more distributed participation. This paper adapts proof of space to enable its use in cryptocurrency, studies the attacks that can arise against a Bitcoin-like blockchain that uses proof of space, and proposes a new blockchain format and transaction types to address these attacks. Our prototype shows that initializing 1 TB for mining takes about a day (a one-off setup cost), and miners spend on average just a fraction of a second per block mined. Finally, we provide a game-theoretic analysis modeling SpaceMint as an extensive game (the canonical game-theoretic notion for games that take place over time) and show that this stylized game satisfies a strong equilibrium notion, thereby arguing for SpaceMint ’s stability and consensus.}, author = {Park, Sunoo and Kwon, Albert and Fuchsbauer, Georg and Gazi, Peter and Alwen, Joel F and Pietrzak, Krzysztof Z}, booktitle = {22nd International Conference on Financial Cryptography and Data Security}, isbn = {9783662583869}, issn = {1611-3349}, location = {Nieuwpoort, Curacao}, pages = {480--499}, publisher = {Springer Nature}, title = {{SpaceMint: A cryptocurrency based on proofs of space}}, doi = {10.1007/978-3-662-58387-6_26}, volume = {10957}, year = {2018}, } @article{7, abstract = {Animal social networks are shaped by multiple selection pressures, including the need to ensure efficient communication and functioning while simultaneously limiting disease transmission. Social animals could potentially further reduce epidemic risk by altering their social networks in the presence of pathogens, yet there is currently no evidence for such pathogen-triggered responses. We tested this hypothesis experimentally in the ant Lasius niger using a combination of automated tracking, controlled pathogen exposure, transmission quantification, and temporally explicit simulations. Pathogen exposure induced behavioral changes in both exposed ants and their nestmates, which helped contain the disease by reinforcing key transmission-inhibitory properties of the colony's contact network. This suggests that social network plasticity in response to pathogens is an effective strategy for mitigating the effects of disease in social groups.}, author = {Stroeymeyt, Nathalie and Grasse, Anna V and Crespi, Alessandro and Mersch, Danielle and Cremer, Sylvia and Keller, Laurent}, issn = {1095-9203}, journal = {Science}, number = {6417}, pages = {941 -- 945}, publisher = {AAAS}, title = {{Social network plasticity decreases disease transmission in a eusocial insect}}, doi = {10.1126/science.aat4793}, volume = {362}, year = {2018}, } @article{70, abstract = {We consider the totally asymmetric simple exclusion process in a critical scaling parametrized by a≥0, which creates a shock in the particle density of order aT−1/3, T the observation time. When starting from step initial data, we provide bounds on the limiting law which in particular imply that in the double limit lima→∞limT→∞ one recovers the product limit law and the degeneration of the correlation length observed at shocks of order 1. This result is shown to apply to a general last-passage percolation model. We also obtain bounds on the two-point functions of several airy processes.}, author = {Nejjar, Peter}, issn = {1980-0436}, journal = {Latin American Journal of Probability and Mathematical Statistics}, number = {2}, pages = {1311--1334}, publisher = {Instituto Nacional de Matematica Pura e Aplicada}, title = {{Transition to shocks in TASEP and decoupling of last passage times}}, doi = {10.30757/ALEA.v15-49}, volume = {15}, year = {2018}, } @article{703, abstract = {We consider the NP-hard problem of MAP-inference for undirected discrete graphical models. We propose a polynomial time and practically efficient algorithm for finding a part of its optimal solution. Specifically, our algorithm marks some labels of the considered graphical model either as (i) optimal, meaning that they belong to all optimal solutions of the inference problem; (ii) non-optimal if they provably do not belong to any solution. With access to an exact solver of a linear programming relaxation to the MAP-inference problem, our algorithm marks the maximal possible (in a specified sense) number of labels. We also present a version of the algorithm, which has access to a suboptimal dual solver only and still can ensure the (non-)optimality for the marked labels, although the overall number of the marked labels may decrease. We propose an efficient implementation, which runs in time comparable to a single run of a suboptimal dual solver. Our method is well-scalable and shows state-of-the-art results on computational benchmarks from machine learning and computer vision.}, author = {Shekhovtsov, Alexander and Swoboda, Paul and Savchynskyy, Bogdan}, issn = {01628828}, journal = {IEEE Transactions on Pattern Analysis and Machine Intelligence}, number = {7}, pages = {1668--1682}, publisher = {IEEE}, title = {{Maximum persistency via iterative relaxed inference with graphical models}}, doi = {10.1109/TPAMI.2017.2730884}, volume = {40}, year = {2018}, } @article{705, abstract = {Although dopamine receptors D1 and D2 play key roles in hippocampal function, their synaptic localization within the hippocampus has not been fully elucidated. In order to understand precise functions of pre- or postsynaptic dopamine receptors (DRs), the development of protocols to differentiate pre- and postsynaptic DRs is essential. So far, most studies on determination and quantification of DRs did not discriminate between subsynaptic localization. Therefore, the aim of the study was to generate a robust workflow for the localization of DRs. This work provides the basis for future work on hippocampal DRs, in light that DRs may have different functions at pre- or postsynaptic sites. Synaptosomes from rat hippocampi isolated by a sucrose gradient protocol were prepared for super-resolution direct stochastic optical reconstruction microscopy (dSTORM) using Bassoon as a presynaptic zone and Homer1 as postsynaptic density marker. Direct labeling of primary validated antibodies against dopamine receptors D1 (D1R) and D2 (D2R) with Alexa Fluor 594 enabled unequivocal assignment of D1R and D2R to both, pre- and postsynaptic sites. D1R immunoreactivity clusters were observed within the presynaptic active zone as well as at perisynaptic sites at the edge of the presynaptic active zone. The results may be useful for the interpretation of previous studies and the design of future work on DRs in the hippocampus. Moreover, the reduction of the complexity of brain tissue by the use of synaptosomal preparations and dSTORM technology may represent a useful tool for synaptic localization of brain proteins.}, author = {Miklosi, Andras and Del Favero, Giorgia and Bulat, Tanja and Höger, Harald and Shigemoto, Ryuichi and Marko, Doris and Lubec, Gert}, journal = {Molecular Neurobiology}, number = {6}, pages = {4857 – 4869}, publisher = {Springer}, title = {{Super resolution microscopical localization of dopamine receptors 1 and 2 in rat hippocampal synaptosomes}}, doi = {10.1007/s12035-017-0688-y}, volume = {55}, year = {2018}, } @inproceedings{7116, abstract = {Training deep learning models has received tremendous research interest recently. In particular, there has been intensive research on reducing the communication cost of training when using multiple computational devices, through reducing the precision of the underlying data representation. Naturally, such methods induce system trade-offs—lowering communication precision could de-crease communication overheads and improve scalability; but, on the other hand, it can also reduce the accuracy of training. In this paper, we study this trade-off space, and ask:Can low-precision communication consistently improve the end-to-end performance of training modern neural networks, with no accuracy loss?From the performance point of view, the answer to this question may appear deceptively easy: compressing communication through low precision should help when the ratio between communication and computation is high. However, this answer is less straightforward when we try to generalize this principle across various neural network architectures (e.g., AlexNet vs. ResNet),number of GPUs (e.g., 2 vs. 8 GPUs), machine configurations(e.g., EC2 instances vs. NVIDIA DGX-1), communication primitives (e.g., MPI vs. NCCL), and even different GPU architectures(e.g., Kepler vs. Pascal). Currently, it is not clear how a realistic realization of all these factors maps to the speed up provided by low-precision communication. In this paper, we conduct an empirical study to answer this question and report the insights.}, author = {Grubic, Demjan and Tam, Leo and Alistarh, Dan-Adrian and Zhang, Ce}, booktitle = {Proceedings of the 21st International Conference on Extending Database Technology}, isbn = {9783893180783}, issn = {2367-2005}, location = {Vienna, Austria}, pages = {145--156}, publisher = {OpenProceedings}, title = {{Synchronous multi-GPU training for deep learning with low-precision communications: An empirical study}}, doi = {10.5441/002/EDBT.2018.14}, year = {2018}, } @inproceedings{7123, abstract = {Population protocols are a popular model of distributed computing, in which n agents with limited local state interact randomly, and cooperate to collectively compute global predicates. Inspired by recent developments in DNA programming, an extensive series of papers, across different communities, has examined the computability and complexity characteristics of this model. Majority, or consensus, is a central task in this model, in which agents need to collectively reach a decision as to which one of two states A or B had a higher initial count. Two metrics are important: the time that a protocol requires to stabilize to an output decision, and the state space size that each agent requires to do so. It is known that majority requires Ω(log log n) states per agent to allow for fast (poly-logarithmic time) stabilization, and that O(log2 n) states are sufficient. Thus, there is an exponential gap between the space upper and lower bounds for this problem. This paper addresses this question. On the negative side, we provide a new lower bound of Ω(log n) states for any protocol which stabilizes in O(n1–c) expected time, for any constant c > 0. This result is conditional on monotonicity and output assumptions, satisfied by all known protocols. Technically, it represents a departure from previous lower bounds, in that it does not rely on the existence of dense configurations. Instead, we introduce a new generalized surgery technique to prove the existence of incorrect executions for any algorithm which would contradict the lower bound. Subsequently, our lower bound also applies to general initial configurations, including ones with a leader. On the positive side, we give a new algorithm for majority which uses O(log n) states, and stabilizes in O(log2 n) expected time. Central to the algorithm is a new leaderless phase clock technique, which allows agents to synchronize in phases of Θ(n log n) consecutive interactions using O(log n) states per agent, exploiting a new connection between population protocols and power-of-two-choices load balancing mechanisms. We also employ our phase clock to build a leader election algorithm with a state space of size O(log n), which stabilizes in O(log2 n) expected time.}, author = {Alistarh, Dan-Adrian and Aspnes, James and Gelashvili, Rati}, booktitle = {Proceedings of the 29th Annual ACM-SIAM Symposium on Discrete Algorithms}, isbn = {9781611975031}, location = {New Orleans, LA, United States}, pages = {2221--2239}, publisher = {ACM}, title = {{Space-optimal majority in population protocols}}, doi = {10.1137/1.9781611975031.144}, year = {2018}, } @article{723, abstract = {Escaping local optima is one of the major obstacles to function optimisation. Using the metaphor of a fitness landscape, local optima correspond to hills separated by fitness valleys that have to be overcome. We define a class of fitness valleys of tunable difficulty by considering their length, representing the Hamming path between the two optima and their depth, the drop in fitness. For this function class we present a runtime comparison between stochastic search algorithms using different search strategies. The (1+1) EA is a simple and well-studied evolutionary algorithm that has to jump across the valley to a point of higher fitness because it does not accept worsening moves (elitism). In contrast, the Metropolis algorithm and the Strong Selection Weak Mutation (SSWM) algorithm, a famous process in population genetics, are both able to cross the fitness valley by accepting worsening moves. We show that the runtime of the (1+1) EA depends critically on the length of the valley while the runtimes of the non-elitist algorithms depend crucially on the depth of the valley. Moreover, we show that both SSWM and Metropolis can also efficiently optimise a rugged function consisting of consecutive valleys.}, author = {Oliveto, Pietro and Paixao, Tiago and Pérez Heredia, Jorge and Sudholt, Dirk and Trubenova, Barbora}, journal = {Algorithmica}, number = {5}, pages = {1604 -- 1633}, publisher = {Springer}, title = {{How to escape local optima in black box optimisation when non elitism outperforms elitism}}, doi = {10.1007/s00453-017-0369-2}, volume = {80}, year = {2018}, } @article{738, abstract = {This paper is devoted to automatic competitive analysis of real-time scheduling algorithms for firm-deadline tasksets, where only completed tasks con- tribute some utility to the system. Given such a taskset T , the competitive ratio of an on-line scheduling algorithm A for T is the worst-case utility ratio of A over the utility achieved by a clairvoyant algorithm. We leverage the theory of quantitative graph games to address the competitive analysis and competitive synthesis problems. For the competitive analysis case, given any taskset T and any finite-memory on- line scheduling algorithm A , we show that the competitive ratio of A in T can be computed in polynomial time in the size of the state space of A . Our approach is flexible as it also provides ways to model meaningful constraints on the released task sequences that determine the competitive ratio. We provide an experimental study of many well-known on-line scheduling algorithms, which demonstrates the feasibility of our competitive analysis approach that effectively replaces human ingenuity (required Preliminary versions of this paper have appeared in Chatterjee et al. ( 2013 , 2014 ). B Andreas Pavlogiannis pavlogiannis@ist.ac.at Krishnendu Chatterjee krish.chat@ist.ac.at Alexander Kößler koe@ecs.tuwien.ac.at Ulrich Schmid s@ecs.tuwien.ac.at 1 IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria 2 Embedded Computing Systems Group, Vienna University of Technology, Treitlstrasse 3, 1040 Vienna, Austria 123 Real-Time Syst for finding worst-case scenarios) by computing power. For the competitive synthesis case, we are just given a taskset T , and the goal is to automatically synthesize an opti- mal on-line scheduling algorithm A , i.e., one that guarantees the largest competitive ratio possible for T . We show how the competitive synthesis problem can be reduced to a two-player graph game with partial information, and establish that the compu- tational complexity of solving this game is Np -complete. The competitive synthesis problem is hence in Np in the size of the state space of the non-deterministic labeled transition system encoding the taskset. Overall, the proposed framework assists in the selection of suitable scheduling algorithms for a given taskset, which is in fact the most common situation in real-time systems design. }, author = {Chatterjee, Krishnendu and Pavlogiannis, Andreas and Kößler, Alexander and Schmid, Ulrich}, journal = {Real-Time Systems}, number = {1}, pages = {166 -- 207}, publisher = {Springer}, title = {{Automated competitive analysis of real time scheduling with graph games}}, doi = {10.1007/s11241-017-9293-4}, volume = {54}, year = {2018}, } @inproceedings{7407, abstract = {Proofs of space (PoS) [Dziembowski et al., CRYPTO'15] are proof systems where a prover can convince a verifier that he "wastes" disk space. PoS were introduced as a more ecological and economical replacement for proofs of work which are currently used to secure blockchains like Bitcoin. In this work we investigate extensions of PoS which allow the prover to embed useful data into the dedicated space, which later can be recovered. Our first contribution is a security proof for the original PoS from CRYPTO'15 in the random oracle model (the original proof only applied to a restricted class of adversaries which can store a subset of the data an honest prover would store). When this PoS is instantiated with recent constructions of maximally depth robust graphs, our proof implies basically optimal security. As a second contribution we show three different extensions of this PoS where useful data can be embedded into the space required by the prover. Our security proof for the PoS extends (non-trivially) to these constructions. We discuss how some of these variants can be used as proofs of catalytic space (PoCS), a notion we put forward in this work, and which basically is a PoS where most of the space required by the prover can be used to backup useful data. Finally we discuss how one of the extensions is a candidate construction for a proof of replication (PoR), a proof system recently suggested in the Filecoin whitepaper. }, author = {Pietrzak, Krzysztof Z}, booktitle = {10th Innovations in Theoretical Computer Science Conference (ITCS 2019)}, isbn = {978-3-95977-095-8}, issn = {1868-8969}, location = {San Diego, CA, United States}, pages = {59:1--59:25}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Proofs of catalytic space}}, doi = {10.4230/LIPICS.ITCS.2019.59}, volume = {124}, year = {2018}, } @article{742, abstract = {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.}, author = {Dotterrer, Dominic and Kaufman, Tali and Wagner, Uli}, journal = {Geometriae Dedicata}, number = {1}, pages = {307–317}, publisher = {Springer}, title = {{On expansion and topological overlap}}, doi = {10.1007/s10711-017-0291-4}, volume = {195}, year = {2018}, }