2016 31st Annual ACM/IEEE Symposium on Logic in Computer Science (LICS)

5-8 July 2016

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Displaying Results 1 - 25 of 90
  • [Front cover]

    Publication Year: 2016, Page(s):c1 - c19
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  • Unifying Logical and Statistical AI

    Publication Year: 2016, Page(s):1 - 11
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (345 KB) | HTML iconHTML

    Intelligent agents must be able to handle the complexity and uncertainty of the real world. Logical AI has focused mainly on the former, and statistical AI on the latter. Markov logic combines the two by attaching weights to first-order formulas and viewing them as templates for features of Markov networks. Inference algorithms for Markov logic draw on ideas from satisfiability, Markov chain Monte... View full abstract»

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  • Two-variable Logic with a Between Relation

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (360 KB) | HTML iconHTML

    We study an extension of FO2[<;], first-order logic interpreted in finite words, in which formulas are restricted to use only two variables. We adjoin to this language two-variable atomic formulas that say, `the letter a appears between positions x and y'. This is, in a sense, the simplest property that is not expressible using only two variables. We present several logics, both firs... View full abstract»

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  • Decidability and Complexity for Quiescent Consistency

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (359 KB) | HTML iconHTML

    Quiescent consistency is a notion of correctness for a concurrent object that gives meaning to the object's behaviours in quiescent states, i.e., states in which none of the object's operations are being executed. The condition enables greater flexibility in object design by allowing more behaviours to be admitted, which in turn allows the algorithms implementing quiescent consistent objects to be... View full abstract»

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  • Duality in Computer Science *

    Publication Year: 2016, Page(s):1 - 15
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (425 KB) | HTML iconHTML

    This is a paper on Stone duality in computer science with special focus on topics with applications in formal language theory. In Section 2 we give a general overview of Stone duality in its various forms: for Boolean algebras, distributive lattices, and frames. For distributive lattices, we discuss both Stone and Priestley duality. We identify how to move between the different dualities and which... View full abstract»

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  • From positive and intuitionistic bounded arithmetic to monotone proof complexity

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (455 KB) | HTML iconHTML

    We study versions of second-order bounded arithmetic where induction and comprehension formulae are positive or where the underlying logic is intuitionistic, examining their relationships to monotone and deep inference proof systems for propositional logic. In the positive setting a restriction of a Paris-Wilkie (PW) style translation yields quasipolynomial-size monotone propositional proofs from ... View full abstract»

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  • Gödel’s functional interpretation and the concept of learning

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (321 KB) | HTML iconHTML

    In this article we study Gödel's functional interpretation from the perspective of learning. We define the notion of a learning algorithm, and show that intuitive realizers of the functional interpretation of both induction and various comprehension schemas can be given in terms of these algorithms. In the case of arithmetical comprehension, we clarify how our learning realizers compare to those o... View full abstract»

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  • Understanding Gentzen and Frege Systems for QBF

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (336 KB) | HTML iconHTML

    Recently Beyersdorff, Bonacina, and Chew [10] introduced a natural class of Frege systems for quantified Boolean formulas (QBF) and showed strong lower bounds for restricted versions of these systems. Here we provide a comprehensive analysis of the new extended Frege system from [10], denoted EE + Vred, which is a natural extension of classical extended Frege EE. Our main results are the following... View full abstract»

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  • Unified Semantics and Proof System for Classical, Intuitionistic and Affine Logics

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (301 KB) | HTML iconHTML

    This paper modifies our previous work in combining classical logic with intuitionistic logic [16], [17] to also include affine linear logic, resulting in a system we call Affine Control Logic. A propositional system with six binary connectives is defined and given a phase space interpretation. Choosing classical, intuitionistic or affine reasoning is entirely dependent on the subformula property. ... View full abstract»

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  • Data Communicating Processes with Unreliable Channels

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (455 KB) | HTML iconHTML

    We extend the classical model of lossy channel systems by considering systems that operate on a finite set of variables ranging over an infinite data domain. Furthermore, each message inside a channel is equipped with a data item representing its value. Although we restrict the model by allowing the variables to be only tested for (dis-)equality, we show that the state reachability problem is unde... View full abstract»

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  • A New Perspective on FO Model Checking of Dense Graph Classes

    Publication Year: 2016, Page(s):1 - 9
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (298 KB) | HTML iconHTML

    We study the FO model checking problem of dense graph classes, namely those which are FO-interpretable in some sparse graph classes. Note that if an input dense graph is given together with the corresponding FO interpretation in a sparse graph, one can easily solve the model checking problem using the existing algorithms for sparse graph classes. However, if the assumed interpretation is not given... View full abstract»

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  • Proving Liveness of Parameterized Programs

    Publication Year: 2016, Page(s):1 - 12
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    Correctness of multi-threaded programs typically requires that they satisfy liveness properties. For example, a program may require that no thread is starved of a shared resource, or that all threads eventually agree on a single value. This paper presents a method for proving that such liveness properties hold. Two particular challenges which are addressed in this work are that (1) the correctness... View full abstract»

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  • Model and Objective Separation with Conditional Lower Bounds: Disjunction is Harder than Conjunction *

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (380 KB) | HTML iconHTML

    Given a model of a system and an objective, the model-checking question asks whether the model satisfies the objective. We study polynomial-time problems in two classical models, graphs and Markov Decision Processes (MDPs), with respect to several fundamental ω-regular objectives, e.g., Rabin and Streett objectives. For many of these problems the best-known upper bounds are quadratic or cubic, yet... View full abstract»

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  • The complexity of regular abstractions of one-counter languages

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (531 KB) | HTML iconHTML

    We study the computational and descriptional complexity of the following transformation: Given a one-counter automaton (OCA) A, construct a nondeterministic finite automaton (NFA) 13 that recognizes an abstraction of the language G(A): its (1) downward closure, (2) upward closure, or (3) Parikh image. For the Parikh image over a fixed alphabet and for the upward and downward closures, we find poly... View full abstract»

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  • Two-Way Visibly Pushdown Automata and Transducers*

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (366 KB) | HTML iconHTML

    Automata-logic connections are pillars of the theory of regular languages. Such connections are harder to obtain for transducers, but important results have been obtained recently for word-to-word transformations, showing that the three following models are equivalent: deterministic two-way transducers, monadic second-order (MSO) transducers, and deterministic one-way automata equipped with a fini... View full abstract»

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  • Automata on Infinite Trees with Equality and Disequality Constraints Between Siblings

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (386 KB) | HTML iconHTML

    This article is inspired by two works from the early 90s. The first one is by Bogaert and Tison who considered a model of automata on finite ranked trees where one can check equality and disequality constraints between direct subtrees: they proved that this class of automata is closed under Boolean operations and that both the emptiness and the finiteness problem of the accepted language are decid... View full abstract»

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  • Plays as Resource Terms via Non-idempotent Intersection Types

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (546 KB) | HTML iconHTML

    A program is interpreted as a collection of resource terms by the Taylor expansion, as a collection of plays by game semantics, and as a collection of types by a non-idempotent intersection type assignment system. This paper investigates the connection between these models and aims to show that they are essentially the same in a certain sense. Technically we study the relational interpretations of... View full abstract»

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  • Perfect-Information Stochastic Games with Generalized Mean-Payoff Objectives*

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (440 KB) | HTML iconHTML

    Graph games provide the foundation for modeling and synthesizing reactive processes. In the synthesis of stochastic reactive processes, the traditional model is perfect-information stochastic games, where some transitions of the game graph are controlled by two adversarial players, and the other transitions are executed probabilistically. We consider such games where the objective is the conjuncti... View full abstract»

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  • Games with bound guess actions

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (387 KB) | HTML iconHTML

    We introduce games with (bound) guess actions. These are games in which the players may be asked along the play to provide numbers that need to satisfy some bounding constraints. These are natural extensions of domination games occurring in the regular cost function theory. In this paper we consider more specifically the case where the constraints to be bounded are regular cost functions, and the ... View full abstract»

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  • Near-Optimal Lower Bounds on Quantifier Depth and Weisfeiler–Leman Refinement Steps

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (338 KB) | HTML iconHTML

    We prove near-optimal trade-offs for quantifier depth versus number of variables in first-order logic by exhibiting pairs of n-element structures that can be distinguished by a k-variable first-order sentence but where every such sentence requires quantifier depth at least nΩ(k/ log k). Our trade-offs also apply to first-order counting logic, and by the known connection to the k-dimensi... View full abstract»

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  • Blockchains and the logic of accountability

    Publication Year: 2016, Page(s):1 - 4
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (131 KB) | HTML iconHTML

    This keynote address poses some blockchain-related challenges to the formal methods community. Although blockchains in some form have been around for a long time, they have only recently risen to prominence. Blockchain technology has recently been embraced by start-ups, financial institutions, and technology companies. The current state of flux in this area provides the computer science research c... View full abstract»

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  • Hanf normal form for first-order logic with unary counting quantifiers

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (379 KB) | HTML iconHTML

    We study the existence of Hanf normal forms for extensions FO(Q) of first-order logic by sets Q ⊆ P(ℕ) of unary counting quantifiers. A formula is in Hanf normal form if it is a Boolean combination of formulas ζ(x̅) describing the isomorphism type of a local neighbourhood around its free variables x̅ and statements of the form “the number of witnesses y of ψ(y) belongs to (Q+k)” where Q ϵ Q, k ϵ ℕ... View full abstract»

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  • Upper Bounds on the Quantifier Depth for Graph Differentiation in First Order Logic

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (340 KB) | HTML iconHTML

    We show that on graphs with n vertices the 2-dimensional Weisfei-ler-Leman algorithm requires at most O(n2/log(n)) iterations to reach stabilization. This in particular shows that the previously best, trivial upper bound of O(n2) is asymptotically not tight. In the logic setting this translates to the statement that if two graphs of size n can be distinguished by a formula in... View full abstract»

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  • Querying Visible and Invisible Information

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (198 KB) | HTML iconHTML

    We provide a wide-ranging study of the scenario where a subset of the relations in the schema are visible - that is, their complete contents are known - while the remaining relations are invisible. We also have integrity constraints (invariants given by logical sentences) which may relate the visible relations to the invisible ones. We want to determine which information about a query (a positive ... View full abstract»

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  • Coinduction All the Way Up

    Publication Year: 2016, Page(s):1 - 10
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (358 KB) | HTML iconHTML

    We revisit coinductive proof principles from a lattice theoretic point of view. By associating to any monotone function a function which we call the companion, we give a new presentation of both Knaster-Tarski's seminal result, and of the more recent theory of enhancements of the coinductive proof method (up-to techniques).The resulting theory encompasses parameterized coinduction, as recently pro... View full abstract»

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