22nd Annual IEEE Symposium on Logic in Computer Science (LICS 2007)

10-14 July 2007

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  • 22nd Annual IEEE Symposium on Logic in Computer Science-Title

    Publication Year: 2007, Page(s):i - iii
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  • 22nd Annual IEEE Symposium on Logic in Computer Science-Copyright

    Publication Year: 2007, Page(s): iv
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  • 22nd Annual IEEE Symposium on Logic in Computer Science - TOC

    Publication Year: 2007, Page(s):v - viii
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  • Foreword

    Publication Year: 2007, Page(s):ix - x
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  • Organizing Committee

    Publication Year: 2007, Page(s):xi - xii
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  • Additional reviewers

    Publication Year: 2007, Page(s): xiii
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  • Normalization by Evaluation for Martin-Löf Type Theory with Typed Equality Judgements

    Publication Year: 2007, Page(s):3 - 12
    Cited by:  Papers (7)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (179 KB) | HTML iconHTML

    The decidability of equality is proved for Martin-Löf type theory with a universe á la Russell and typed beta-eta- equality judgements. A corollary of this result is that the constructor for dependent function types is injective, a property which is crucial for establishing the correctness of the type-checking algorithm. The decision procedure uses normalization by evaluation, an algorithm which f... View full abstract»

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  • Strong Normalization as Safe Interaction

    Publication Year: 2007, Page(s):13 - 22
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (194 KB) | HTML iconHTML

    When enriching the lambda-calculus with rewriting, union types may be needed to type all strongly normalizing terms. However, with rewriting, the elimination rule (orE) of union types may also allow to type non normalizing terms (in which case we say that (orE) is unsafe). This occurs in particular with non-determinism, but also with some confluent systems. It appears that studying the safety of (... View full abstract»

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  • A Dependent Set Theory

    Publication Year: 2007, Page(s):23 - 34
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (249 KB) | HTML iconHTML

    Set theories are traditionally based on first-order logic. We show that in a constructive setting, basing a set theory on a dependent logic yields many benefits. To this end, we introduce a dependent impredicative constructive set theory which we call IZF<sub>D</sub>. Using realizability, we prove that the underlying lambda calculus weakly normalizes, thus enabling program extraction f... View full abstract»

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  • Some Methods of Problem Solving in Elementary Geometry

    Publication Year: 2007, Page(s):35 - 40
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (285 KB) | HTML iconHTML

    Many elementary problems in geometry arise as part of the proof of the Kepler conjecture on sphere packings. In the original proof, most of these problems were solved by hand. This article investigates the methods that were used in the original proof and describes a number of other methods that might be used to automate the proofs of these problems. A companion article presents the collection of e... View full abstract»

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  • Principles of Superdeduction

    Publication Year: 2007, Page(s):41 - 50
    Cited by:  Papers (4)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (297 KB) | HTML iconHTML

    In predicate logic, the proof that a theorem P holds in a theory Th is typically conducted in natural deduction or in the sequent calculus using all the information contained in the theory in a uniform way. Introduced ten years ago, deduction modulo allows us to make use of the computational part of the theory Th for true computations modulo which deductions are performed. Focusing on the sequent ... View full abstract»

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  • Complete Sequent Calculi for Induction and Infinite Descent

    Publication Year: 2007, Page(s):51 - 62
    Cited by:  Papers (6)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (217 KB) | HTML iconHTML

    This paper compares two different styles of reasoning with inductively defined predicates, each style being encapsulated by a corresponding sequent calculus proof system. The first system supports traditional proof by induction, with induction rules formulated as sequent rules for introducing inductively defined predicates on the left of sequents. We show this system to be cut-free complete with r... View full abstract»

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  • Highly Efficient Secrecy-Preserving Proofs of Correctness of Computations and Applications

    Publication Year: 2007, Page(s):63 - 76
    Cited by:  Papers (5)  |  Patents (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (264 KB) | HTML iconHTML

    We present a highly efficient method for proving correctness of computations while preserving secrecy of the input values. This is done in an Evaluator-Prover model which can also be realized by a secure processor. We describe an application to secure auctions. View full abstract»

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  • A Complete Axiomatization of Knowledge and Cryptography

    Publication Year: 2007, Page(s):77 - 88
    Cited by:  Papers (8)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (180 KB) | HTML iconHTML

    The combination of first-order epistemic logic with formal cryptography offers a potentially powerful framework for security protocol verification. In this paper, cryptography is modelled using private constants and one-way computable operations, as in the applied Pi-calculus. To give the concept of knowledge a computational justification, we propose a generalized Kripke semantics that uses permut... View full abstract»

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  • Limits of Multi-Discounted Markov Decision Processes

    Publication Year: 2007, Page(s):89 - 98
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (347 KB) | HTML iconHTML

    Markov decision processes (MDPs) are controllable discrete event systems with stochastic transitions. The payoff received by the controller can be evaluated in different ways, depending on the payoff function the MDP is equipped with. For example a mean-payoff function evaluates average performance, whereas a discounted payoff function gives more weights to earlier performance by means of a discou... View full abstract»

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  • Game Relations and Metrics

    Publication Year: 2007, Page(s):99 - 108
    Cited by:  Papers (10)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (211 KB) | HTML iconHTML

    We consider two-player games played over finite state spaces for an infinite number of rounds. At each state, the players simultaneously choose moves; the moves determine a successor state. It is often advantageous for players to choose probability distributions over moves, rather than single moves. Given a goal (e.g., "reach a target state"), the question of winning is thus a probabilistic one: "... View full abstract»

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  • The Cost of Punctuality

    Publication Year: 2007, Page(s):109 - 120
    Cited by:  Papers (11)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (301 KB) | HTML iconHTML

    In an influential paper titled "The benefits of relaxing punctuality" [2], Alur, Feder, and Henzinger introduced Metric Interval Temporal Logic (MITL) as a fragment of the real-time logic metric temporal logic (MTL) in which exact or punctual timing constraints are banned. Their main result showed that model checking and satisfiability for MITL are both EXPSPACE-Complete. Until recently, it was wi... View full abstract»

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  • Two-way unary temporal logic over trees

    Publication Year: 2007, Page(s):121 - 130
    Cited by:  Papers (8)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (265 KB) | HTML iconHTML

    We consider a temporal logic EF + F<sup>-1</sup> for unranked, unordered finite trees. The logic has two operators: EFphi , which says "in some proper descendant phi holds", and F<sup>-1</sup>phi , which says "in some proper ancestor phi holds". We present an algorithm for deciding if a regular language of unranked finite trees can be expressed in EF + F<sup>-1</su... View full abstract»

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  • Alternation-free modal mu-calculus for data trees

    Publication Year: 2007, Page(s):131 - 140
    Cited by:  Papers (5)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (230 KB) | HTML iconHTML

    An alternation-free modal mu-calculus over data trees is introduced and studied. A data tree is an unranked ordered tree whose every node is labelled by a letter from a finite alphabet and an element ("datum") from an infinite set. For expressing data-sensitive properties, the calculus is equipped with freeze quantification. A freeze quantifier stores in a register the datum labelling the current ... View full abstract»

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  • A Contraction Method to Decide MSO Theories of Deterministic Trees

    Publication Year: 2007, Page(s):141 - 150
    Cited by:  Papers (1)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (314 KB) | HTML iconHTML

    In this paper we generalize the contraction method, originally proposed by Elgot and Rabin and later extended by Carton and Thomas, from labeled linear orderings to colored deterministic trees. The method we propose rests on a suitable notion of indistinguishability of trees with respect to tree automata that allows us to reduce a number of instances of the acceptance problem for tree automata to ... View full abstract»

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  • First-Order and Temporal Logics for Nested Words

    Publication Year: 2007, Page(s):151 - 160
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (206 KB) | HTML iconHTML

    Nested words are a structured model of execution paths in procedural programs, reflecting their call and return nesting structure. Finite nested words also capture the structure of parse trees and other tree-structured data, such as XML. We provide new temporal logics for finite and infinite nested words, which are natural extensions of LTL, and prove that these logics are first-order expressively... View full abstract»

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  • A Robust Class of Context-Sensitive Languages

    Publication Year: 2007, Page(s):161 - 170
    Cited by:  Papers (28)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (250 KB) | HTML iconHTML

    We define a new class of languages defined by multi-stack automata that forms a robust subclass of context-sensitive languages, with decidable emptiness and closure under boolean operations. This class, called multi-stack visibly pushdown languages (MVPLs), is defined using multi-stack pushdown automata with two restrictions: (a) the pushdown automaton is visible, i.e. the input letter determines ... View full abstract»

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  • A New Efficient Simulation Equivalence Algorithm

    Publication Year: 2007, Page(s):171 - 180
    Cited by:  Papers (9)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (279 KB) | HTML iconHTML

    It is well known that simulation equivalence is an appropriate abstraction to be used in model checking because it strongly preserves ACTL* and provides a better space reduction than bisimulation equivalence. However, computing simulation equivalence is harder than computing bisimulation equivalence. A number of algorithms for computing simulation equivalence exist. Let Sigma denote the state spac... View full abstract»

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  • Infinite State AMC-Model Checking for Cryptographic Protocols

    Publication Year: 2007, Page(s):181 - 192
    Cited by:  Papers (3)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (190 KB) | HTML iconHTML

    Only very little is known about the automatic analysis of cryptographic protocols for game-theoretic security properties. In this paper, we therefore study decidability and complexity of the model checking problem for AMC-formulas over infinite state concurrent game structures induced by cryptographic protocols and the Dolev-Yao intruder. We show that the problem is NEXPTIME-complete when making r... View full abstract»

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  • Symmetric Datalog and Constraint Satisfaction Problems in Logspace

    Publication Year: 2007, Page(s):193 - 202
    Cited by:  Papers (6)
    Request permission for reuse | Click to expandAbstract | PDF file iconPDF (248 KB) | HTML iconHTML

    We introduce symmetric Datalog, a syntactic restriction of linear Datalog and show that its expressive power is exactly that of restricted symmetric Krom monotone SNP. The deep result of Reingold [17] on the complexity of undirected connectivity suffices to show that symmetric Datalog queries can be evaluated in logarithmic space. We show that for a number of constraint languages Gamma, the comple... View full abstract»

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