@inproceedings{3155,
abstract = {We propose synchronous interfaces, a new interface theory for discrete-time systems. We use an application to time-triggered scheduling to drive the design choices for our formalism; in particular, additionally to deriving useful mathematical properties, we focus on providing a syntax which is adapted to natural high-level system modeling. As a result, we develop an interface model that relies on a guarded-command based language and is equipped with shared variables and explicit discrete-time clocks. We define all standard interface operations: compatibility checking, composition, refinement, and shared refinement. Apart from the synchronous interface model, the contribution of this paper is the establishment of a formal relation between interface theories and real-time scheduling, where we demonstrate a fully automatic framework for the incremental computation of time-triggered schedules.},
author = {Delahaye, Benoît and Fahrenberg, Uli and Henzinger, Thomas A and Legay, Axel and Nickovic, Dejan},
location = {Stockholm, Sweden},
pages = {203 -- 218},
publisher = {Springer},
title = {{Synchronous interface theories and time triggered scheduling}},
doi = {10.1007/978-3-642-30793-5_13},
volume = {7273},
year = {2012},
}
@inproceedings{3129,
abstract = {Let K be a simplicial complex and g the rank of its p-th homology group Hp(K) defined with ℤ2 coefficients. We show that we can compute a basis H of Hp(K) and annotate each p-simplex of K with a binary vector of length g with the following property: the annotations, summed over all p-simplices in any p-cycle z, provide the coordinate vector of the homology class [z] in the basis H. The basis and the annotations for all simplices can be computed in O(n ω ) time, where n is the size of K and ω < 2.376 is a quantity so that two n×n matrices can be multiplied in O(n ω ) time. The precomputed annotations permit answering queries about the independence or the triviality of p-cycles efficiently.
Using annotations of edges in 2-complexes, we derive better algorithms for computing optimal basis and optimal homologous cycles in 1 - dimensional homology. Specifically, for computing an optimal basis of H1(K) , we improve the previously known time complexity from O(n 4) to O(n ω + n 2 g ω − 1). Here n denotes the size of the 2-skeleton of K and g the rank of H1(K) . Computing an optimal cycle homologous to a given 1-cycle is NP-hard even for surfaces and an algorithm taking 2 O(g) nlogn time is known for surfaces. We extend this algorithm to work with arbitrary 2-complexes in O(n ω ) + 2 O(g) n 2logn time using annotations.
},
author = {Busaryev, Oleksiy and Cabello, Sergio and Chen, Chao and Dey, Tamal and Wang, Yusu},
location = {Helsinki, Finland},
pages = {189 -- 200},
publisher = {Springer},
title = {{Annotating simplices with a homology basis and its applications}},
doi = {10.1007/978-3-642-31155-0_17},
volume = {7357},
year = {2012},
}
@article{3131,
abstract = {In large populations, many beneficial mutations may be simultaneously available and may compete with one another, slowing adaptation. By finding the probability of fixation of a favorable allele in a simple model of a haploid sexual population, we find limits to the rate of adaptive substitution, Λ, that depend on simple parameter combinations. When variance in fitness is low and linkage is loose, the baseline rate of substitution is Λ 0=2NU〈s〉 is the population size, U is the rate of beneficial mutations per genome, and 〈s〉 is their mean selective advantage. Heritable variance ν in log fitness due to unlinked loci reduces Λ by e -4ν under polygamy and e -8ν under monogamy. With a linear genetic map of length R Morgans, interference is yet stronger. We use a scaling argument to show that the density of adaptive substitutions depends on s, N, U, and R only through the baseline density: Λ/R=F(Λ 0/R). Under the approximation that the interference due to different sweeps adds up, we show that Λ/R~(Λ 0/R)/(1+2Λ 0/R), implying that interference prevents the rate of adaptive substitution from exceeding one per centimorgan per 200 generations. Simulations and numerical calculations confirm the scaling argument and confirm the additive approximation for Λ 0/R 1; for higher Λ 0/R, the rate of adaptation grows above R/2, but only very slowly. We also consider the effect of sweeps on neutral diversity and show that, while even occasional sweeps can greatly reduce neutral diversity, this effect saturates as sweeps become more common-diversity can be maintained even in populations experiencing very strong interference. Our results indicate that for some organisms the rate of adaptive substitution may be primarily recombination-limited, depending only weakly on the mutation supply and the strength of selection.},
author = {Weissman, Daniel and Barton, Nicholas H},
journal = {PLoS Genetics},
number = {6},
publisher = {Public Library of Science},
title = {{Limits to the rate of adaptive substitution in sexual populations}},
doi = {10.1371/journal.pgen.1002740},
volume = {8},
year = {2012},
}
@article{3117,
abstract = {We consider the problem of minimizing a function represented as a sum of submodular terms. We assume each term allows an efficient computation of exchange capacities. This holds, for example, for terms depending on a small number of variables, or for certain cardinality-dependent terms. A naive application of submodular minimization algorithms would not exploit the existence of specialized exchange capacity subroutines for individual terms. To overcome this, we cast the problem as a submodular flow (SF) problem in an auxiliary graph in such a way that applying most existing SF algorithms would rely only on these subroutines. We then explore in more detail Iwata's capacity scaling approach for submodular flows (Iwata 1997 [19]). In particular, we show how to improve its complexity in the case when the function contains cardinality-dependent terms.},
author = {Kolmogorov, Vladimir},
journal = {Discrete Applied Mathematics},
number = {15},
pages = {2246 -- 2258},
publisher = {Elsevier},
title = {{Minimizing a sum of submodular functions}},
doi = {10.1016/j.dam.2012.05.025},
volume = {160},
year = {2012},
}
@article{3167,
author = {Weber, Michele},
journal = {Science},
number = {6077},
pages = {32--34},
publisher = {American Association for the Advancement of Science},
title = {{NextGen speaks 13 }},
doi = {10.1126/science.336.6077.32},
volume = {336},
year = {2012},
}
@article{3256,
abstract = {We use a distortion to define the dual complex of a cubical subdivision of ℝ n as an n-dimensional subcomplex of the nerve of the set of n-cubes. Motivated by the topological analysis of high-dimensional digital image data, we consider such subdivisions defined by generalizations of quad- and oct-trees to n dimensions. Assuming the subdivision is balanced, we show that mapping each vertex to the center of the corresponding n-cube gives a geometric realization of the dual complex in ℝ n.},
author = {Edelsbrunner, Herbert and Kerber, Michael},
journal = {Discrete & Computational Geometry},
number = {2},
pages = {393 -- 414},
publisher = {Springer},
title = {{Dual complexes of cubical subdivisions of ℝn}},
doi = {10.1007/s00454-011-9382-4},
volume = {47},
year = {2012},
}
@article{3244,
author = {Danowski, Patrick},
journal = {BuB – Forum Bibliothek und Information},
number = {4},
pages = {284},
publisher = {Bock & Herchen Verlag},
title = {{Die Zeit des Abwartens ist vorbei!}},
volume = {64},
year = {2012},
}
@inproceedings{3282,
abstract = {Traditionally, symmetric-key message authentication codes (MACs) are easily built from pseudorandom functions (PRFs). In this work we propose a wide variety of other approaches to building efficient MACs, without going through a PRF first. In particular, unlike deterministic PRF-based MACs, where each message has a unique valid tag, we give a number of probabilistic MAC constructions from various other primitives/assumptions. Our main results are summarized as follows: We show several new probabilistic MAC constructions from a variety of general assumptions, including CCA-secure encryption, Hash Proof Systems and key-homomorphic weak PRFs. By instantiating these frameworks under concrete number theoretic assumptions, we get several schemes which are more efficient than just using a state-of-the-art PRF instantiation under the corresponding assumption. For probabilistic MACs, unlike deterministic ones, unforgeability against a chosen message attack (uf-cma ) alone does not imply security if the adversary can additionally make verification queries (uf-cmva ). We give an efficient generic transformation from any uf-cma secure MAC which is "message-hiding" into a uf-cmva secure MAC. This resolves the main open problem of Kiltz et al. from Eurocrypt'11; By using our transformation on their constructions, we get the first efficient MACs from the LPN assumption. While all our new MAC constructions immediately give efficient actively secure, two-round symmetric-key identification schemes, we also show a very simple, three-round actively secure identification protocol from any weak PRF. In particular, the resulting protocol is much more efficient than the trivial approach of building a regular PRF from a weak PRF. © 2012 International Association for Cryptologic Research.},
author = {Dodis, Yevgeniy and Pietrzak, Krzysztof Z and Kiltz, Eike and Wichs, Daniel},
location = {Cambridge, UK},
pages = {355 -- 374},
publisher = {Springer},
title = {{Message authentication, revisited}},
doi = {10.1007/978-3-642-29011-4_22},
volume = {7237},
year = {2012},
}
@inproceedings{3124,
abstract = {We consider the problem of inference in a graphical model with binary variables. While in theory it is arguably preferable to compute marginal probabilities, in practice researchers often use MAP inference due to the availability of efficient discrete optimization algorithms. We bridge the gap between the two approaches by introducing the Discrete Marginals technique in which approximate marginals are obtained by minimizing an objective function with unary and pairwise terms over a discretized domain. This allows the use of techniques originally developed for MAP-MRF inference and learning. We explore two ways to set up the objective function - by discretizing the Bethe free energy and by learning it from training data. Experimental results show that for certain types of graphs a learned function can outperform the Bethe approximation. We also establish a link between the Bethe free energy and submodular functions.
},
author = {Korc, Filip and Kolmogorov, Vladimir and Lampert, Christoph},
location = {Edinburgh, Scotland},
publisher = {ICML},
title = {{Approximating marginals using discrete energy minimization}},
year = {2012},
}
@misc{5396,
abstract = {We consider the problem of inference in agraphical model with binary variables. While in theory it is arguably preferable to compute marginal probabilities, in practice researchers often use MAP inference due to the availability of efficient discrete optimization algorithms. We bridge the gap between the two approaches by introducing the Discrete Marginals technique in which approximate marginals are obtained by minimizing an objective function with unary and pair-wise terms over a discretized domain. This allows the use of techniques originally devel-oped for MAP-MRF inference and learning. We explore two ways to set up the objective function - by discretizing the Bethe free energy and by learning it from training data. Experimental results show that for certain types of graphs a learned function can out-perform the Bethe approximation. We also establish a link between the Bethe free energy and submodular functions.},
author = {Korc, Filip and Kolmogorov, Vladimir and Lampert, Christoph},
issn = {2664-1690},
pages = {13},
publisher = {IST Austria},
title = {{Approximating marginals using discrete energy minimization}},
doi = {10.15479/AT:IST-2012-0003},
year = {2012},
}
@inbook{5745,
author = {Gupta, Ashutosh},
booktitle = {Automated Technology for Verification and Analysis},
isbn = {9783642333859},
issn = {0302-9743},
location = {Thiruvananthapuram, Kerala, India},
pages = {107--121},
publisher = {Springer Berlin Heidelberg},
title = {{Improved Single Pass Algorithms for Resolution Proof Reduction}},
doi = {10.1007/978-3-642-33386-6_10},
volume = {7561},
year = {2012},
}
@article{3249,
abstract = {Boolean notions of correctness are formalized by preorders on systems. Quantitative measures of correctness can be formalized by real-valued distance functions between systems, where the distance between implementation and specification provides a measure of "fit" or "desirability". We extend the simulation preorder to the quantitative setting by making each player of a simulation game pay a certain price for her choices. We use the resulting games with quantitative objectives to define three different simulation distances. The correctness distance measures how much the specification must be changed in order to be satisfied by the implementation. The coverage distance measures how much the implementation restricts the degrees of freedom offered by the specification. The robustness distance measures how much a system can deviate from the implementation description without violating the specification. We consider these distances for safety as well as liveness specifications. The distances can be computed in polynomial time for safety specifications, and for liveness specifications given by weak fairness constraints. We show that the distance functions satisfy the triangle inequality, that the distance between two systems does not increase under parallel composition with a third system, and that the distance between two systems can be bounded from above and below by distances between abstractions of the two systems. These properties suggest that our simulation distances provide an appropriate basis for a quantitative theory of discrete systems. We also demonstrate how the robustness distance can be used to measure how many transmission errors are tolerated by error correcting codes.},
author = {Cerny, Pavol and Henzinger, Thomas A and Radhakrishna, Arjun},
journal = {Theoretical Computer Science},
number = {1},
pages = {21 -- 35},
publisher = {Elsevier},
title = {{Simulation distances}},
doi = {10.1016/j.tcs.2011.08.002},
volume = {413},
year = {2012},
}
@article{2950,
abstract = {Contractile actomyosin rings drive various fundamental morphogenetic processes ranging from cytokinesis to wound healing. Actomyosin rings are generally thought to function by circumferential contraction. Here, we show that the spreading of the enveloping cell layer (EVL) over the yolk cell during zebrafish gastrulation is driven by a contractile actomyosin ring. In contrast to previous suggestions, we find that this ring functions not only by circumferential contraction but also by a flow-friction mechanism. This generates a pulling force through resistance against retrograde actomyosin flow. EVL spreading proceeds normally in situations where circumferential contraction is unproductive, indicating that the flow-friction mechanism is sufficient. Thus, actomyosin rings can function in epithelial morphogenesis through a combination of cable-constriction and flow-friction mechanisms.},
author = {Behrndt, Martin and Salbreux, Guillaume and Campinho, Pedro and Hauschild, Robert and Oswald, Felix and Roensch, Julia and Grill, Stephan and Heisenberg, Carl-Philipp J},
journal = {Science},
number = {6104},
pages = {257 -- 260},
publisher = {American Association for the Advancement of Science},
title = {{Forces driving epithelial spreading in zebrafish gastrulation}},
doi = {10.1126/science.1224143},
volume = {338},
year = {2012},
}
@misc{5377,
abstract = {Two-player games on graphs are central in many problems in formal verification and program analysis such as synthesis and verification of open systems. In this work we consider solving recursive game graphs (or pushdown game graphs) that can model the control flow of sequential programs with recursion. While pushdown games have been studied before with qualitative objectives, such as reachability and ω-regular objectives, in this work we study for the first time such games with the most well-studied quantitative objective, namely, mean-payoff objectives. In pushdown games two types of strategies are relevant: (1) global strategies, that depend on the entire global history; and (2) modular strategies, that have only local memory and thus do not depend on the context of invocation, but only on the history of the current invocation of the module. Our main results are as follows: (1) One-player pushdown games with mean-payoff objectives under global strategies are decidable in polynomial time. (2) Two- player pushdown games with mean-payoff objectives under global strategies are undecidable. (3) One-player pushdown games with mean-payoff objectives under modular strategies are NP- hard. (4) Two-player pushdown games with mean-payoff objectives under modular strategies can be solved in NP (i.e., both one-player and two-player pushdown games with mean-payoff objectives under modular strategies are NP-complete). We also establish the optimal strategy complexity showing that global strategies for mean-payoff objectives require infinite memory even in one-player pushdown games; and memoryless modular strategies are sufficient in two- player pushdown games. Finally we also show that all the problems have the same complexity if the stack boundedness condition is added, where along with the mean-payoff objective the player must also ensure that the stack height is bounded.},
author = {Chatterjee, Krishnendu and Velner, Yaron},
issn = {2664-1690},
pages = {33},
publisher = {IST Austria},
title = {{Mean-payoff pushdown games}},
doi = {10.15479/AT:IST-2012-0002},
year = {2012},
}
@article{2967,
abstract = {For programs whose data variables range over Boolean or finite domains, program verification is decidable, and this forms the basis of recent tools for software model checking. In this article, we consider algorithmic verification of programs that use Boolean variables, and in addition, access a single read-only array whose length is potentially unbounded, and whose elements range over an unbounded data domain. We show that the reachability problem, while undecidable in general, is (1) PSPACE-complete for programs in which the array-accessing for-loops are not nested, (2) decidable for a restricted class of programs with doubly nested loops. The second result establishes connections to automata and logics defining languages over data words.},
author = {Alur, Rajeev and Cerny, Pavol and Weinstein, Scott},
journal = {ACM Transactions on Computational Logic (TOCL)},
number = {3},
publisher = {ACM},
title = {{Algorithmic analysis of array-accessing programs}},
doi = {10.1145/2287718.2287727},
volume = {13},
year = {2012},
}
@inproceedings{2955,
abstract = {We consider two-player stochastic games played on finite graphs with reachability objectives where the first player tries to ensure a target state to be visited almost-surely (i.e., with probability 1), or positively (i.e., with positive probability), no matter the strategy of the second player. We classify such games according to the information and the power of randomization available to the players. On the basis of information, the game can be one-sided with either (a) player 1, or (b) player 2 having partial observation (and the other player has perfect observation), or two-sided with (c) both players having partial observation. On the basis of randomization, the players (a) may not be allowed to use randomization (pure strategies), or (b) may choose a probability distribution over actions but the actual random choice is external and not visible to the player (actions invisible), or (c) may use full randomization. Our main results for pure strategies are as follows. (1) For one-sided games with player 1 having partial observation we show that (in contrast to full randomized strategies) belief-based (subset-construction based) strategies are not sufficient, and we present an exponential upper bound on memory both for almostsure and positive winning strategies; we show that the problem of deciding the existence of almost-sure and positive winning strategies for player 1 is EXPTIME-complete. (2) For one-sided games with player 2 having partial observation we show that non-elementary memory is both necessary and sufficient for both almost-sure and positive winning strategies. (3) We show that for the general (two-sided) case finite-memory strategies are sufficient for both positive and almost-sure winning, and at least non-elementary memory is required. We establish the equivalence of the almost-sure winning problems for pure strategies and for randomized strategies with actions invisible. Our equivalence result exhibits serious flaws in previous results of the literature: we show a non-elementary memory lower bound for almost-sure winning whereas an exponential upper bound was previously claimed.},
author = {Chatterjee, Krishnendu and Doyen, Laurent},
booktitle = {Proceedings of the 2012 27th Annual ACM/IEEE Symposium on Logic in Computer Science},
location = {Dubrovnik, Croatia},
publisher = {IEEE},
title = {{Partial-observation stochastic games: How to win when belief fails}},
doi = {10.1109/LICS.2012.28},
year = {2012},
}
@inproceedings{2936,
abstract = {The notion of delays arises naturally in many computational models, such as, in the design of circuits, control systems, and dataflow languages. In this work, we introduce automata with delay blocks (ADBs), extending finite state automata with variable time delay blocks, for deferring individual transition output symbols, in a discrete-time setting. We show that the ADB languages strictly subsume the regular languages, and are incomparable in expressive power to the context-free languages. We show that ADBs are closed under union, concatenation and Kleene star, and under intersection with regular languages, but not closed under complementation and intersection with other ADB languages. We show that the emptiness and the membership problems are decidable in polynomial time for ADBs, whereas the universality problem is undecidable. Finally we consider the linear-time model checking problem, i.e., whether the language of an ADB is contained in a regular language, and show that the model checking problem is PSPACE-complete. Copyright 2012 ACM.},
author = {Chatterjee, Krishnendu and Henzinger, Thomas A and Prabhu, Vinayak},
booktitle = {roceedings of the tenth ACM international conference on Embedded software},
location = {Tampere, Finland},
pages = {43 -- 52},
publisher = {ACM},
title = {{Finite automata with time delay blocks}},
doi = {10.1145/2380356.2380370},
year = {2012},
}
@inproceedings{3251,
abstract = {Many infinite state systems can be seen as well-structured transition systems (WSTS), i.e., systems equipped with a well-quasi-ordering on states that is also a simulation relation. WSTS are an attractive target for formal analysis because there exist generic algorithms that decide interesting verification problems for this class. Among the most popular algorithms are acceleration-based forward analyses for computing the covering set. Termination of these algorithms can only be guaranteed for flattable WSTS. Yet, many WSTS of practical interest are not flattable and the question whether any given WSTS is flattable is itself undecidable. We therefore propose an analysis that computes the covering set and captures the essence of acceleration-based algorithms, but sacrifices precision for guaranteed termination. Our analysis is an abstract interpretation whose abstract domain builds on the ideal completion of the well-quasi-ordered state space, and a widening operator that mimics acceleration and controls the loss of precision of the analysis. We present instances of our framework for various classes of WSTS. Our experience with a prototype implementation indicates that, despite the inherent precision loss, our analysis often computes the precise covering set of the analyzed system.},
author = {Zufferey, Damien and Wies, Thomas and Henzinger, Thomas A},
location = {Philadelphia, PA, USA},
pages = {445 -- 460},
publisher = {Springer},
title = {{Ideal abstractions for well structured transition systems}},
doi = {10.1007/978-3-642-27940-9_29},
volume = {7148},
year = {2012},
}
@article{3314,
abstract = {We introduce two-level discounted and mean-payoff games played by two players on a perfect-information stochastic game graph. The upper level game is a discounted or mean-payoff game and the lower level game is a (undiscounted) reachability game. Two-level games model hierarchical and sequential decision making under uncertainty across different time scales. For both discounted and mean-payoff two-level games, we show the existence of pure memoryless optimal strategies for both players and an ordered field property. We show that if there is only one player (Markov decision processes), then the values can be computed in polynomial time. It follows that whether the value of a player is equal to a given rational constant in two-level discounted or mean-payoff games can be decided in NP ∩ coNP. We also give an alternate strategy improvement algorithm to compute the value. © 2012 World Scientific Publishing Company.},
author = {Chatterjee, Krishnendu and Majumdar, Ritankar},
journal = {International Journal of Foundations of Computer Science},
number = {3},
pages = {609 -- 625},
publisher = {World Scientific Publishing},
title = {{Discounting and averaging in games across time scales}},
doi = {10.1142/S0129054112400308},
volume = {23},
year = {2012},
}
@inproceedings{496,
abstract = {We study the expressive power of logical interpretations on the class of scattered trees, namely those with countably many infinite branches. Scattered trees can be thought of as the tree analogue of scattered linear orders. Every scattered tree has an ordinal rank that reflects the structure of its infinite branches. We prove, roughly, that trees and orders of large rank cannot be interpreted in scattered trees of small rank. We consider a quite general notion of interpretation: each element of the interpreted structure is represented by a set of tuples of subsets of the interpreting tree. Our trees are countable, not necessarily finitely branching, and may have finitely many unary predicates as labellings. We also show how to replace injective set-interpretations in (not necessarily scattered) trees by 'finitary' set-interpretations.},
author = {Rabinovich, Alexander and Rubin, Sasha},
location = {Dubrovnik, Croatia},
publisher = {IEEE},
title = {{Interpretations in trees with countably many branches}},
doi = {10.1109/LICS.2012.65},
year = {2012},
}
@inproceedings{2715,
abstract = {We consider Markov decision processes (MDPs) with specifications given as Büchi (liveness) objectives. We consider the problem of computing the set of almost-sure winning vertices from where the objective can be ensured with probability 1. We study for the first time the average case complexity of the classical algorithm for computing the set of almost-sure winning vertices for MDPs with Büchi objectives. Our contributions are as follows: First, we show that for MDPs with constant out-degree the expected number of iterations is at most logarithmic and the average case running time is linear (as compared to the worst case linear number of iterations and quadratic time complexity). Second, for the average case analysis over all MDPs we show that the expected number of iterations is constant and the average case running time is linear (again as compared to the worst case linear number of iterations and quadratic time complexity). Finally we also show that given that all MDPs are equally likely, the probability that the classical algorithm requires more than constant number of iterations is exponentially small.},
author = {Chatterjee, Krishnendu and Joglekar, Manas and Shah, Nisarg},
location = {Hyderabad, India},
pages = {461 -- 473},
publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
title = {{Average case analysis of the classical algorithm for Markov decision processes with Büchi objectives}},
doi = {10.4230/LIPIcs.FSTTCS.2012.461},
volume = {18},
year = {2012},
}
@inproceedings{3162,
abstract = {Given a dense-time real-valued signal and a parameterized temporal logic formula with both magnitude and timing parameters, we compute the subset of the parameter space that renders the formula satisfied by the trace. We provide two preliminary implementations, one which follows the exact semantics and attempts to compute the validity domain by quantifier elimination in linear arithmetics and one which conducts adaptive search in the parameter space.},
author = {Asarin, Eugene and Donzé, Alexandre and Maler, Oded and Nickovic, Dejan},
location = {San Francisco, CA, United States},
pages = {147 -- 160},
publisher = {Springer},
title = {{Parametric identification of temporal properties}},
doi = {10.1007/978-3-642-29860-8_12},
volume = {7186},
year = {2012},
}
@article{2949,
author = {Dupret, David and Csicsvari, Jozsef L},
journal = {Nature Neuroscience},
number = {11},
pages = {1471 -- 1472},
publisher = {Nature Publishing Group},
title = {{The medial entorhinal cortex keeps Up}},
doi = {10.1038/nn.3245},
volume = {15},
year = {2012},
}
@inproceedings{2937,
abstract = {Developers building cryptography into security-sensitive applications face a daunting task. Not only must they understand the security guarantees delivered by the constructions they choose, they must also implement and combine them correctly and efficiently. Cryptographic compilers free developers from this task by turning high-level specifications of security goals into efficient implementations. Yet, trusting such tools is hard as they rely on complex mathematical machinery and claim security properties that are subtle and difficult to verify. In this paper we present ZKCrypt, an optimizing cryptographic compiler achieving an unprecedented level of assurance without sacrificing practicality for a comprehensive class of cryptographic protocols, known as Zero-Knowledge Proofs of Knowledge. The pipeline of ZKCrypt integrates purpose-built verified compilers and verifying compilers producing formal proofs in the CertiCrypt framework. By combining the guarantees delivered by each stage, ZKCrypt provides assurance that the output implementation securely realizes the abstract proof goal given as input. We report on the main characteristics of ZKCrypt, highlight new definitions and concepts at its foundations, and illustrate its applicability through a representative example of an anonymous credential system.},
author = {Almeida, José and Barbosa, Manuel and Bangerter, Endre and Barthe, Gilles and Krenn, Stephan and Béguelin, Santiago},
booktitle = {Proceedings of the 2012 ACM conference on Computer and communications security},
location = {Raleigh, NC, USA},
pages = {488 -- 500},
publisher = {ACM},
title = {{Full proof cryptography: Verifiable compilation of efficient zero-knowledge protocols}},
doi = {10.1145/2382196.2382249},
year = {2012},
}
@article{2951,
abstract = {Differential cell adhesion and cortex tension are thought to drive cell sorting by controlling cell-cell contact formation. Here, we show that cell adhesion and cortex tension have different mechanical functions in controlling progenitor cell-cell contact formation and sorting during zebrafish gastrulation. Cortex tension controls cell-cell contact expansion by modulating interfacial tension at the contact. By contrast, adhesion has little direct function in contact expansion, but instead is needed to mechanically couple the cortices of adhering cells at their contacts, allowing cortex tension to control contact expansion. The coupling function of adhesion is mediated by E-cadherin and limited by the mechanical anchoring of E-cadherin to the cortex. Thus, cell adhesion provides the mechanical scaffold for cell cortex tension to drive cell sorting during gastrulation.},
author = {Maître, Jean-Léon and Berthoumieux, Hélène and Krens, Gabriel and Salbreux, Guillaume and Julicher, Frank and Paluch, Ewa and Heisenberg, Carl-Philipp J},
journal = {Science},
number = {6104},
pages = {253 -- 256},
publisher = {American Association for the Advancement of Science},
title = {{Adhesion functions in cell sorting by mechanically coupling the cortices of adhering cells}},
doi = {10.1126/science.1225399},
volume = {338},
year = {2012},
}
@article{2968,
abstract = {Little is known about the stability of trophic relationships in complex natural communities over evolutionary timescales. Here, we use sequence data from 18 nuclear loci to reconstruct and compare the intraspecific histories of major Pleistocene refugial populations in the Middle East, the Balkans and Iberia in a guild of four Chalcid parasitoids (Cecidostiba fungosa, Cecidostiba semifascia, Hobbya stenonota and Mesopolobus amaenus) all attacking Cynipid oak galls. We develop a likelihood method to numerically estimate models of divergence between three populations from multilocus data. We investigate the power of this framework on simulated data, and-using triplet alignments of intronic loci-quantify the support for all possible divergence relationships between refugial populations in the four parasitoids. Although an East to West order of population divergence has highest support in all but one species, we cannot rule out alternative population tree topologies. Comparing the estimated times of population splits between species, we find that one species, M. amaenus, has a significantly older history than the rest of the guild and must have arrived in central Europe at least one glacial cycle prior to other guild members. This suggests that although all four species may share a common origin in the East, they expanded westwards into Europe at different times. © 2012 Blackwell Publishing Ltd.},
author = {Lohse, Konrad and Barton, Nicholas H and Melika, George and Stone, Graham},
journal = {Molecular Ecology},
number = {18},
pages = {4605 -- 4617},
publisher = {Wiley-Blackwell},
title = {{A likelihood based comparison of population histories in a parasitoid guild}},
doi = {10.1111/j.1365-294X.2012.05700.x},
volume = {21},
year = {2012},
}
@article{2970,
abstract = {Morphogen gradients regulate the patterning and growth of many tissues, hence a key question is how they are established and maintained during development. Theoretical descriptions have helped to explain how gradient shape is controlled by the rates of morphogen production, spreading and degradation. These effective rates have been measured using fluorescence recovery after photobleaching (FRAP) and photoactivation. To unravel which molecular events determine the effective rates, such tissue-level assays have been combined with genetic analysis, high-resolution assays, and models that take into account interactions with receptors, extracellular components and trafficking. Nevertheless, because of the natural and experimental data variability, and the underlying assumptions of transport models, it remains challenging to conclusively distinguish between cellular mechanisms.},
author = {Kicheva, Anna and Bollenbach, Mark Tobias and Wartlick, Ortrud and Julicher, Frank and Gonzalez Gaitan, Marcos},
journal = {Current Opinion in Genetics & Development},
number = {6},
pages = {527 -- 532},
publisher = {Elsevier},
title = {{Investigating the principles of morphogen gradient formation: from tissues to cells}},
doi = {10.1016/j.gde.2012.08.004},
volume = {22},
year = {2012},
}
@article{2963,
abstract = {Zebra finches are an ubiquitous model system for the study of vocal learning in animal communication. Their song has been well described, but its possible function(s) in social communication are only partly understood. The so-called ‘directed song’ is a high-intensity, high-performance song given during courtship in close proximity to the female, which is known to mediate mate choice and mating. However, this singing mode constitutes only a fraction of zebra finch males’ prolific song output. Potential communicative functions of their second, ‘undirected’ singing mode remain unresolved in the face of contradicting reports of both facilitating and inhibiting effects of social company on singing. We addressed this issue by experimentally manipulating social contexts in a within-subject design, comparing a solo versus male or female only company condition, each lasting for 24 hours. Males’ total song output was significantly higher when a conspecific was in audible and visible distance than when they were alone. Male and female company had an equally facilitating effect on song output. Our findings thus indicate that singing motivation is facilitated rather than inhibited by social company, suggesting that singing in zebra finches might function both in inter- and intrasexual communication. },
author = {Jesse, Fabienne and Riebel, Katharina},
journal = {Behavioural Processes},
number = {3},
pages = {262 -- 266},
publisher = {Elsevier},
title = {{Social facilitation of male song by male and female conspecifics in the zebra finch, Taeniopygia guttata}},
doi = {10.1016/j.beproc.2012.09.006},
volume = {91},
year = {2012},
}
@article{3156,
abstract = {Dispersal is crucial for gene flow and often determines the long-term stability of meta-populations, particularly in rare species with specialized life cycles. Such species are often foci of conservation efforts because they suffer disproportionally from degradation and fragmentation of their habitat. However, detailed knowledge of effective gene flow through dispersal is often missing, so that conservation strategies have to be based on mark-recapture observations that are suspected to be poor predictors of long-distance dispersal. These constraints have been especially severe in the study of butterfly populations, where microsatellite markers have been difficult to develop. We used eight microsatellite markers to analyse genetic population structure of the Large Blue butterfly Maculinea arion in Sweden. During recent decades, this species has become an icon of insect conservation after massive decline throughout Europe and extinction in Britain followed by reintroduction of a seed population from the Swedish island of Öland. We find that populations are highly structured genetically, but that gene flow occurs over distances 15 times longer than the maximum distance recorded from mark-recapture studies, which can only be explained by maximum dispersal distances at least twice as large as previously accepted. However, we also find evidence that gaps between sites with suitable habitat exceeding ∼ 20 km induce genetic erosion that can be detected from bottleneck analyses. Although further work is needed, our results suggest that M. arion can maintain fully functional metapopulations when they consist of optimal habitat patches that are no further apart than ∼10 km.},
author = {Ugelvig, Line V and Andersen, Anne and Boomsma, Jacobus and Nash, David},
journal = {Molecular Ecology},
number = {13},
pages = {3224 -- 3236},
publisher = {Wiley-Blackwell},
title = {{Dispersal and gene flow in the rare parasitic Large Blue butterfly Maculinea arion}},
doi = {10.1111/j.1365-294X.2012.05592.x},
volume = {21},
year = {2012},
}
@article{3118,
abstract = {We present a method for recovering a temporally coherent, deforming triangle mesh with arbitrarily changing topology from an incoherent sequence of static closed surfaces. We solve this problem using the surface geometry alone, without any prior information like surface templates or velocity fields. Our system combines a proven strategy for triangle mesh improvement, a robust multi-resolution non-rigid registration routine, and a reliable technique for changing surface mesh topology. We also introduce a novel topological constraint enforcement algorithm to ensure that the output and input always have similar topology. We apply our technique to a series of diverse input data from video reconstructions, physics simulations, and artistic morphs. The structured output of our algorithm allows us to efficiently track information like colors and displacement maps, recover velocity information, and solve PDEs on the mesh as a post process.},
author = {Bojsen-Hansen, Morten and Li, Hao and Wojtan, Christopher J},
journal = {ACM Transactions on Graphics},
number = {4},
publisher = {ACM},
title = {{Tracking surfaces with evolving topology}},
doi = {10.1145/2185520.2185549},
volume = {31},
year = {2012},
}
@article{3120,
abstract = {We introduce a strategy based on Kustin-Miller unprojection that allows us to construct many hundreds of Gorenstein codimension 4 ideals with 9 × 16 resolutions (that is, nine equations and sixteen first syzygies). Our two basic games are called Tom and Jerry; the main application is the biregular construction of most of the anticanonically polarised Mori Fano 3-folds of Altinok's thesis. There are 115 cases whose numerical data (in effect, the Hilbert series) allow a Type I projection. In every case, at least one Tom and one Jerry construction works, providing at least two deformation families of quasismooth Fano 3-folds having the same numerics but different topology. © 2012 Copyright Foundation Compositio Mathematica.},
author = {Brown, Gavin and Kerber, Michael and Reid, Miles},
journal = {Compositio Mathematica},
number = {4},
pages = {1171 -- 1194},
publisher = {Cambridge University Press},
title = {{Fano 3 folds in codimension 4 Tom and Jerry Part I}},
doi = {10.1112/S0010437X11007226},
volume = {148},
year = {2012},
}
@article{3132,
abstract = {Reproductive division of labour is a characteristic trait of social insects. The dominant reproductive individual, often the queen, uses chemical communication and/or behaviour to maintain her social status. Queens of many social insects communicate their fertility status via cuticle-bound substances. As these substances usually possess a low volatility, their range in queen–worker communication is potentially limited. Here, we investigate the range and impact of behavioural and chemical queen signals on workers of the ant Temnothorax longispinosus. We compared the behaviour and ovary development of workers subjected to three different treatments: workers with direct chemical and physical contact to the queen, those solely under the influence of volatile queen substances and those entirely separated from the queen. In addition to short-ranged queen signals preventing ovary development in workers, we discovered a novel secondary pathway influencing worker behaviour. Workers with no physical contact to the queen, but exposed to volatile substances, started to develop their ovaries, but did not change their behaviour compared to workers in direct contact to the queen. In contrast, workers in queen-separated groups showed both increased ovary development and aggressive dominance interactions. We conclude that T. longispinosus queens influence worker ovary development and behaviour via two independent signals, both ensuring social harmony within the colony.},
author = {Konrad, Matthias and Pamminger, Tobias and Foitzik, Susanne},
journal = {Naturwissenschaften},
number = {8},
pages = {627 -- 636},
publisher = {Springer},
title = {{Two pathways ensuring social harmony}},
doi = {10.1007/s00114-012-0943-z},
volume = {99},
year = {2012},
}
@article{3245,
abstract = {How cells orchestrate their behavior during collective migration is a long-standing question. Using magnetic tweezers to apply mechanical stimuli to Xenopus mesendoderm cells, Weber etal. (2012) now reveal, in this issue of Developmental Cell, a cadherin-mediated mechanosensitive response that promotes cell polarization and movement persistence during the collective mesendoderm migration in gastrulation.},
author = {Behrndt, Martin and Heisenberg, Carl-Philipp J},
journal = {Developmental Cell},
number = {1},
pages = {3 -- 4},
publisher = {Cell Press},
title = {{Spurred by resistance mechanosensation in collective migration}},
doi = {10.1016/j.devcel.2011.12.018},
volume = {22},
year = {2012},
}
@article{3257,
abstract = {Consider a convex relaxation f̂ of a pseudo-Boolean function f. We say that the relaxation is totally half-integral if f̂(x) is a polyhedral function with half-integral extreme points x, and this property is preserved after adding an arbitrary combination of constraints of the form x i=x j, x i=1-x j, and x i=γ where γ∈{0,1,1/2} is a constant. A well-known example is the roof duality relaxation for quadratic pseudo-Boolean functions f. We argue that total half-integrality is a natural requirement for generalizations of roof duality to arbitrary pseudo-Boolean functions. Our contributions are as follows. First, we provide a complete characterization of totally half-integral relaxations f̂ by establishing a one-to-one correspondence with bisubmodular functions. Second, we give a new characterization of bisubmodular functions. Finally, we show some relationships between general totally half-integral relaxations and relaxations based on the roof duality. On the conceptual level, our results show that bisubmodular functions provide a natural generalization of the roof duality approach to higher-order terms. This can be viewed as a non-submodular analogue of the fact that submodular functions generalize the s-t minimum cut problem with non-negative weights to higher-order terms.},
author = {Kolmogorov, Vladimir},
journal = {Discrete Applied Mathematics},
number = {4-5},
pages = {416 -- 426},
publisher = {Elsevier},
title = {{Generalized roof duality and bisubmodular functions}},
doi = {10.1016/j.dam.2011.10.026},
volume = {160},
year = {2012},
}
@article{3310,
abstract = {The theory of persistent homology opens up the possibility to reason about topological features of a space or a function quantitatively and in combinatorial terms. We refer to this new angle at a classical subject within algebraic topology as a point calculus, which we present for the family of interlevel sets of a real-valued function. Our account of the subject is expository, devoid of proofs, and written for non-experts in algebraic topology.},
author = {Bendich, Paul and Cabello, Sergio and Edelsbrunner, Herbert},
journal = {Pattern Recognition Letters},
number = {11},
pages = {1436 -- 1444},
publisher = {Elsevier},
title = {{A point calculus for interlevel set homology}},
doi = {10.1016/j.patrec.2011.10.007},
volume = {33},
year = {2012},
}
@article{3168,
abstract = {The induction of a signaling pathway is characterized by transient complex formation and mutual posttranslational modification of proteins. To faithfully capture this combinatorial process in a mathematical model is an important challenge in systems biology. Exploiting the limited context on which most binding and modification events are conditioned, attempts have been made to reduce the combinatorial complexity by quotienting the reachable set of molecular species into species aggregates while preserving the deterministic semantics of the thermodynamic limit. Recently, we proposed a quotienting that also preserves the stochastic semantics and that is complete in the sense that the semantics of individual species can be recovered from the aggregate semantics. In this paper, we prove that this quotienting yields a sufficient condition for weak lumpability (that is to say that the quotient system is still Markovian for a given set of initial distributions) and that it gives rise to a backward Markov bisimulation between the original and aggregated transition system (which means that the conditional probability of being in a given state in the original system knowing that we are in its equivalence class is an invariant of the system). We illustrate the framework on a case study of the epidermal growth factor (EGF)/insulin receptor crosstalk.},
author = {Feret, Jérôme and Henzinger, Thomas A and Koeppl, Heinz and Petrov, Tatjana},
journal = {Theoretical Computer Science},
pages = {137 -- 164},
publisher = {Elsevier},
title = {{Lumpability abstractions of rule based systems}},
doi = {10.1016/j.tcs.2011.12.059},
volume = {431},
year = {2012},
}
@article{3846,
abstract = {We summarize classical and recent results about two-player games played on graphs with ω-regular objectives. These games have applications in the verification and synthesis of reactive systems. Important distinctions are whether a graph game is turn-based or concurrent; deterministic or stochastic; zero-sum or not. We cluster known results and open problems according to these classifications.},
author = {Chatterjee, Krishnendu and Henzinger, Thomas A},
journal = {Journal of Computer and System Sciences},
number = {2},
pages = {394 -- 413},
publisher = {Elsevier},
title = {{A survey of stochastic ω regular games}},
doi = {10.1016/j.jcss.2011.05.002},
volume = {78},
year = {2012},
}
@article{2848,
abstract = {We study evolutionary game theory in a setting where individuals learn from each other. We extend the traditional approach by assuming that a population contains individuals with different learning abilities. In particular, we explore the situation where individuals have different search spaces, when attempting to learn the strategies of others. The search space of an individual specifies the set of strategies learnable by that individual. The search space is genetically given and does not change under social evolutionary dynamics. We introduce a general framework and study a specific example in the context of direct reciprocity. For this example, we obtain the counter intuitive result that cooperation can only evolve for intermediate benefit-to-cost ratios, while small and large benefit-to-cost ratios favor defection. Our paper is a step toward making a connection between computational learning theory and evolutionary game dynamics.},
author = {Chatterjee, Krishnendu and Zufferey, Damien and Nowak, Martin},
journal = {Journal of Theoretical Biology},
pages = {161 -- 173},
publisher = {Elsevier},
title = {{Evolutionary game dynamics in populations with different learners}},
doi = {10.1016/j.jtbi.2012.02.021},
volume = {301},
year = {2012},
}
@inproceedings{2956,
abstract = {Two-player games on graphs are central in many problems in formal verification and program analysis such as synthesis and verification of open systems. In this work we consider solving recursive game graphs (or pushdown game graphs) that can model the control flow of sequential programs with recursion. While pushdown games have been studied before with qualitative objectives, such as reachability and parity objectives, in this work we study for the first time such games with the most well-studied quantitative objective, namely, mean payoff objectives. In pushdown games two types of strategies are relevant: (1) global strategies, that depend on the entire global history; and (2) modular strategies, that have only local memory and thus do not depend on the context of invocation, but only on the history of the current invocation of the module. Our main results are as follows: (1) One-player pushdown games with mean-payoff objectives under global strategies are decidable in polynomial time. (2) Two-player pushdown games with mean-payoff objectives under global strategies are undecidable. (3) One-player pushdown games with mean-payoff objectives under modular strategies are NP-hard. (4) Two-player pushdown games with mean-payoff objectives under modular strategies can be solved in NP (i.e., both one-player and two-player pushdown games with mean-payoff objectives under modular strategies are NP-complete). We also establish the optimal strategy complexity showing that global strategies for mean-payoff objectives require infinite memory even in one-player pushdown games; and memoryless modular strategies are sufficient in two-player pushdown games. Finally we also show that all the problems have the same computational complexity if the stack boundedness condition is added, where along with the mean-payoff objective the player must also ensure that the stack height is bounded.},
author = {Chatterjee, Krishnendu and Velner, Yaron},
booktitle = {Proceedings of the 2012 27th Annual ACM/IEEE Symposium on Logic in Computer Science},
location = {Dubrovnik, Croatia },
publisher = {IEEE},
title = {{Mean payoff pushdown games}},
doi = {10.1109/LICS.2012.30},
year = {2012},
}
@inproceedings{3341,
abstract = {We consider two-player stochastic games played on a finite state space for an infinite number of rounds. The games are concurrent: in each round, the two players (player 1 and player 2) choose their moves independently and simultaneously; the current state and the two moves determine a probability distribution over the successor states. We also consider the important special case of turn-based stochastic games where players make moves in turns, rather than concurrently. We study concurrent games with \omega-regular winning conditions specified as parity objectives. The value for player 1 for a parity objective is the maximal probability with which the player can guarantee the satisfaction of the objective against all strategies of the opponent. We study the problem of continuity and robustness of the value function in concurrent and turn-based stochastic parity gameswith respect to imprecision in the transition probabilities. We present quantitative bounds on the difference of the value function (in terms of the imprecision of the transition probabilities) and show the value continuity for structurally equivalent concurrent games (two games are structurally equivalent if the support of the transition function is same and the probabilities differ). We also show robustness of optimal strategies for structurally equivalent turn-based stochastic parity games. Finally we show that the value continuity property breaks without the structurally equivalent assumption (even for Markov chains) and show that our quantitative bound is asymptotically optimal. Hence our results are tight (the assumption is both necessary and sufficient) and optimal (our quantitative bound is asymptotically optimal).},
author = {Chatterjee, Krishnendu},
location = {Tallinn, Estonia},
pages = {270 -- 285},
publisher = {Springer},
title = {{Robustness of structurally equivalent concurrent parity games}},
doi = {10.1007/978-3-642-28729-9_18},
volume = {7213},
year = {2012},
}
@inproceedings{3252,
abstract = {We study the automatic synthesis of fair non-repudiation protocols, a class of fair exchange protocols, used for digital contract signing. First, we show how to specify the objectives of the participating agents, the trusted third party (TTP) and the protocols as path formulas in Linear Temporal Logic (LTL) and prove that the satisfaction of the objectives of the agents and the TTP imply satisfaction of the protocol objectives. We then show that weak (co-operative) co-synthesis and classical (strictly competitive) co-synthesis fail in synthesizing these protocols, whereas assume-guarantee synthesis (AGS) succeeds. We demonstrate the success of assume-guarantee synthesis as follows: (a) any solution of assume-guarantee synthesis is attack-free; no subset of participants can violate the objectives of the other participants without violating their own objectives; (b) the Asokan-Shoup-Waidner (ASW) certified mail protocol that has known vulnerabilities is not a solution of AGS; and (c) the Kremer-Markowitch (KM) non-repudiation protocol is a solution of AGS. To our knowledge this is the first application of synthesis to fair non-repudiation protocols, and our results show how synthesis can generate correct protocols and automatically discover vulnerabilities. The solution to assume-guarantee synthesis can be computed efficiently as the secure equilibrium solution of three-player graph games. © 2012 Springer-Verlag.},
author = {Chatterjee, Krishnendu and Raman, Vishwanath},
location = {Philadelphia, PA, USA},
pages = {152 -- 168},
publisher = {Springer},
title = {{Synthesizing protocols for digital contract signing}},
doi = {10.1007/978-3-642-27940-9_11},
volume = {7148},
year = {2012},
}
@inproceedings{497,
abstract = {One central issue in the formal design and analysis of reactive systems is the notion of refinement that asks whether all behaviors of the implementation is allowed by the specification. The local interpretation of behavior leads to the notion of simulation. Alternating transition systems (ATSs) provide a general model for composite reactive systems, and the simulation relation for ATSs is known as alternating simulation. The simulation relation for fair transition systems is called fair simulation. In this work our main contributions are as follows: (1) We present an improved algorithm for fair simulation with Büchi fairness constraints; our algorithm requires O(n 3·m) time as compared to the previous known O(n 6)-time algorithm, where n is the number of states and m is the number of transitions. (2) We present a game based algorithm for alternating simulation that requires O(m2)-time as compared to the previous known O((n·m)2)-time algorithm, where n is the number of states and m is the size of transition relation. (3) We present an iterative algorithm for alternating simulation that matches the time complexity of the game based algorithm, but is more space efficient than the game based algorithm. © Krishnendu Chatterjee, Siddhesh Chaubal, and Pritish Kamath.},
author = {Chatterjee, Krishnendu and Chaubal, Siddhesh and Kamath, Pritish},
location = {Fontainebleau, France},
pages = {167 -- 182},
publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik},
title = {{Faster algorithms for alternating refinement relations}},
doi = {10.4230/LIPIcs.CSL.2012.167},
volume = {16},
year = {2012},
}
@misc{5378,
abstract = {One central issue in the formal design and analysis of reactive systems is the notion of refinement that asks whether all behaviors of the implementation is allowed by the specification. The local interpretation of behavior leads to the notion of simulation. Alternating transition systems (ATSs) provide a general model for composite reactive systems, and the simulation relation for ATSs is known as alternating simulation. The simulation relation for fair transition systems is called fair simulation. In this work our main contributions are as follows: (1) We present an improved algorithm for fair simulation with Büchi fairness constraints; our algorithm requires O(n3 · m) time as compared to the previous known O(n6)-time algorithm, where n is the number of states and m is the number of transitions. (2) We present a game based algorithm for alternating simulation that requires O(m2)-time as compared to the previous known O((n · m)2)-time algorithm, where n is the number of states and m is the size of transition relation. (3) We present an iterative algorithm for alternating simulation that matches the time complexity of the game based algorithm, but is more space efficient than the game based algorithm.},
author = {Chatterjee, Krishnendu and Chaubal, Siddhesh and Kamath, Pritish},
issn = {2664-1690},
pages = {21},
publisher = {IST Austria},
title = {{Faster algorithms for alternating refinement relations}},
doi = {10.15479/AT:IST-2012-0001},
year = {2012},
}
@inproceedings{3125,
abstract = {We propose a new learning method to infer a mid-level feature representation that combines the advantage of semantic attribute representations with the higher expressive power of non-semantic features. The idea lies in augmenting an existing attribute-based representation with additional dimensions for which an autoencoder model is coupled with a large-margin principle. This construction allows a smooth transition between the zero-shot regime with no training example, the unsupervised regime with training examples but without class labels, and the supervised regime with training examples and with class labels. The resulting optimization problem can be solved efficiently, because several of the necessity steps have closed-form solutions. Through extensive experiments we show that the augmented representation achieves better results in terms of object categorization accuracy than the semantic representation alone.},
author = {Sharmanska, Viktoriia and Quadrianto, Novi and Lampert, Christoph},
location = {Florence, Italy},
number = {PART 5},
pages = {242 -- 255},
publisher = {Springer},
title = {{Augmented attribute representations}},
doi = {10.1007/978-3-642-33715-4_18},
volume = {7576},
year = {2012},
}
@article{2318,
abstract = {We show that bosons interacting via pair potentials with negative scattering length form bound states for a suitable number of particles. In other words, the absence of many-particle bound states of any kind implies the non-negativity of the scattering length of the interaction potential. },
author = {Seiringer, Robert},
journal = {Journal of Spectral Theory},
number = {3},
pages = {321--328},
publisher = {European Mathematical Society},
title = {{Absence of bound states implies non-negativity of the scattering length}},
doi = {10.4171/JST/31},
volume = {2},
year = {2012},
}
@article{2902,
abstract = {We present an algorithm for simplifying linear cartographic objects and results obtained with a computer program implementing this algorithm. },
author = {Edelsbrunner, Herbert and Musin, Oleg and Ukhalov, Alexey and Yakimova, Olga and Alexeev, Vladislav and Bogaevskaya, Victoriya and Gorohov, Andrey and Preobrazhenskaya, Margarita},
journal = {Modeling and Analysis of Information Systems},
number = {6},
pages = {152 -- 160},
publisher = {Technische Universität Darmstadt},
title = {{Fractal and computational geometry for generalizing cartographic objects}},
volume = {19},
year = {2012},
}
@inproceedings{2825,
abstract = {We study the problem of maximum marginal prediction (MMP) in probabilistic graphical models, a task that occurs, for example, as the Bayes optimal decision rule under a Hamming loss. MMP is typically performed as a two-stage procedure: one estimates each variable's marginal probability and then forms a prediction from the states of maximal probability. In this work we propose a simple yet effective technique for accelerating MMP when inference is sampling-based: instead of the above two-stage procedure we directly estimate the posterior probability of each decision variable. This allows us to identify the point of time when we are sufficiently certain about any individual decision. Whenever this is the case, we dynamically prune the variables we are confident about from the underlying factor graph. Consequently, at any time only samples of variables whose decision is still uncertain need to be created. Experiments in two prototypical scenarios, multi-label classification and image inpainting, show that adaptive sampling can drastically accelerate MMP without sacrificing prediction accuracy.},
author = {Lampert, Christoph},
location = {Lake Tahoe, NV, United States},
pages = {82 -- 90},
publisher = {Neural Information Processing Systems},
title = {{Dynamic pruning of factor graphs for maximum marginal prediction}},
volume = {1},
year = {2012},
}
@article{2849,
author = {Edelsbrunner, Herbert and Strelkova, Nataliya},
journal = {Russian Mathematical Surveys},
number = {6},
pages = {1167 -- 1168},
publisher = {IOP Publishing Ltd.},
title = {{On the configuration space of Steiner minimal trees}},
doi = {10.1070/RM2012v067n06ABEH004820},
volume = {67},
year = {2012},
}
@article{2945,
abstract = {In search of foreign antigens, lymphocytes recirculate from the blood, through lymph nodes, into lymphatics and back to the blood. Dendritic cells also migrate to lymph nodes for optimal interaction with lymphocytes. This continuous trafficking of immune cells into and out of lymph nodes is essential for immune surveillance of foreign invaders. In this article, we review our current understanding of the functions of high endothelial venules (HEVs), stroma and lymphatics in the entry, positioning and exit of immune cells in lymph nodes during homeostasis, and we highlight the unexpected role of dendritic cells in the control of lymphocyte homing through HEVs.},
author = {Girard, Jean and Moussion, Christine and Förster, Reinhold},
journal = {Nature Reviews Immunology},
number = {11},
pages = {762 -- 773},
publisher = {Nature Publishing Group},
title = {{HEVs, lymphatics and homeostatic immune cell trafficking in lymph nodes}},
doi = {10.1038/nri3298},
volume = {12},
year = {2012},
}
@article{2938,
abstract = {Social insects have a very high potential to become invasive pest species. Here, we explore how their social lifestyle and their interaction with parasites may contribute to this invasive success. Similar to solitary species, parasite release followed by the evolution of increased competitive ability can promote establishment of introduced social insect hosts in their introduced range. Genetic bottlenecks during introduction of low numbers of founder individuals decrease the genetic diversity at three levels: the population, the colony and the individual, with the colony level being specific to social insects. Reduced genetic diversity can affect both the individual immune system and the collective colony-level disease defences (social immunity). Still, the dual immune system is likely to make social insects more robust to parasite attack. Changes in social structure from small, family-based, territorially aggressive societies in native populations towards huge networks of cooperating nests (unicoloniality) occur in some invasive social insects, for example, most invasive ants and some termites. Unicoloniality is likely to affect disease dynamics in multiple ways. The free exchange of individuals within the population leads to an increased genetic heterogeneity among individuals of a single nest, thereby decreasing disease transmission. However, the multitude of reproductively active queens per colony buffers the effect of individual diseased queens and their offspring, which may result in a higher level of vertical disease transmission in unicolonial societies. Lastly, unicoloniality provides a competitive advantage over native species, allowing them to quickly become the dominant species in the habitat, which in turn selects for parasite adaptation to this common host genotype and thus eventually a high parasite pressure. Overall, invasions by insect societies are characterized by general features applying to all introduced species, as well as idiosyncrasies that emerge from their social lifestyle. It is important to study these effects in concert to be able to develop efficient management and biocontrol strategies. © 2012 British Ecological Society.},
author = {Ugelvig, Line V and Cremer, Sylvia},
journal = {Functional Ecology},
number = {6},
pages = {1300 -- 1312},
publisher = {Wiley-Blackwell},
title = {{Effects of social immunity and unicoloniality on host parasite interactions in invasive insect societies}},
doi = {10.1111/1365-2435.12013},
volume = {26},
year = {2012},
}