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38
Privacy and contextual integrity: Framework and applications
 In IEEE Symposium on Security and Privacy
, 2006
"... Contextual integrity is a conceptual framework for understanding privacy expectations and their implications developed in the literature on law, public policy, and political philosophy. We formalize some aspects of contextual integrity in a logical framework for expressing and reasoning about norms ..."
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Cited by 55 (13 self)
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Contextual integrity is a conceptual framework for understanding privacy expectations and their implications developed in the literature on law, public policy, and political philosophy. We formalize some aspects of contextual integrity in a logical framework for expressing and reasoning about norms of transmission of personal information. In comparison with access control and privacy policy frameworks such as RBAC, EPAL, and P3P, these norms focus on who personal information is about, how it is transmitted, and past and future actions by both the subject and the users of the information. Norms can be positive or negative depending on whether they refer to actions that are allowed or disallowed. Our model is expressive enough to capture naturally many notions of privacy found in legislation, including those found in HIPAA, COPPA, and GLBA. A number of important problems regarding compliance with privacy norms, future requirements associated with specific actions, and relations between policies and legal standards reduce to standard decision procedures for temporal logic. 1
The Complexity of Temporal Logic Model Checking
, 2002
"... Temporal logic. Logical formalisms for reasoning about time and the timing of events appear in several fields: physics, philosophy, linguistics, etc. Not surprisingly, they also appear in computer science, a field where logic is ubiquitous. Here temporal logics are used in automated reasoning, in pl ..."
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Cited by 32 (0 self)
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Temporal logic. Logical formalisms for reasoning about time and the timing of events appear in several fields: physics, philosophy, linguistics, etc. Not surprisingly, they also appear in computer science, a field where logic is ubiquitous. Here temporal logics are used in automated reasoning, in planning, in semantics of programming languages, in artificial intelligence, etc. There is one area of computer science where temporal logic has been unusually successful: the specification and verification of programs and systems, an area we shall just call programming for simplicity. In today's curricula, thousands of programmers first learn about temporal logic in a course on model checking!
Temporal Logic with Forgettable Past
 In LICS’02
, 2002
"... We investigate NLTL, a lineartime temporal logic with forgettable past. NLTL can be exponentially more succinct than LTL + Past (which in turn can be more succinct than LTL). We study satisfiability and model checking for NLTL and provide optimal automatatheoretic algorithms for these EXPSPACEcom ..."
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Cited by 28 (4 self)
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We investigate NLTL, a lineartime temporal logic with forgettable past. NLTL can be exponentially more succinct than LTL + Past (which in turn can be more succinct than LTL). We study satisfiability and model checking for NLTL and provide optimal automatatheoretic algorithms for these EXPSPACEcomplete problems. 1.
Model Checking a Path (Preliminary Report
 In 14th Int. Conf. Concurrency Theory, Lecture Notes in Computer Science 2761
, 2003
"... Abstract. We consider the problem of checking whether a finite (or ultimately periodic) run satisfies a temporal logic formula. This problem is at the heart of “runtime verification ” but it also appears in many other situations. By considering several extended temporal logics, we show that the prob ..."
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Cited by 21 (1 self)
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Abstract. We consider the problem of checking whether a finite (or ultimately periodic) run satisfies a temporal logic formula. This problem is at the heart of “runtime verification ” but it also appears in many other situations. By considering several extended temporal logics, we show that the problem of model checking a path can usually be solved efficiently, and profit from specialized algorithms. We further show it is possible to efficiently check paths given in compressed form. 1
An AutomataTheoretic Approach to Constraint LTL
, 2003
"... We consider an extension of lineartime temporal logic (LTL) with constraints interpreted over a concrete domain. We use a new automatatheoretic technique to show pspace decidability of the logic for the constraint systems (Z, <, =) and (N, <, =). Along the way, we give an automatatheoretic proof ..."
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Cited by 20 (7 self)
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We consider an extension of lineartime temporal logic (LTL) with constraints interpreted over a concrete domain. We use a new automatatheoretic technique to show pspace decidability of the logic for the constraint systems (Z, <, =) and (N, <, =). Along the way, we give an automatatheoretic proof of a result of [BC02] when the constraint system D satisfies the completion property. Our decision procedures extend easily to handle extensions of the logic with past operators and constants, as well as an extension of the temporal language itself to monadic second order logic. Finally, we show that the logic...
Deterministic Generators and Games for LTL Fragments
 ACM Trans. Comput. Log
, 2001
"... Deciding infinite twoplayer games on finite graphs with the winning condition specified by a linear temporal logic (Ltl) formula, is known to be 2Exptimecomplete. In this paper, we identify Ltl fragments of lower complexity. Solving Ltl games typically involves a doublyexponential translation from ..."
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Cited by 20 (1 self)
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Deciding infinite twoplayer games on finite graphs with the winning condition specified by a linear temporal logic (Ltl) formula, is known to be 2Exptimecomplete. In this paper, we identify Ltl fragments of lower complexity. Solving Ltl games typically involves a doublyexponential translation from Ltl formulas to deterministic !automata. First, we show that the longest distance (length of the longest simple path) of the generator is also an important parameter, by giving an O(d log n)space procedure to solve a Buchi game on a graph with n vertices and longest distance d. Then, for the Ltl fragment with only eventualities and conjunctions, we provide a translation to deterministic generators of exponential size and linear longest distance, show both of these bounds to be optimal, and prove the corresponding games to be Pspacecomplete. Introducing next modalities in this fragment, we provide a translation to deterministic generators still of exponential size but also with exponential longest distance, show both of these bounds to be optimal, and prove the corresponding games to be Exptimecomplete. For the fragment resulting by further adding disjunctions, we provide a translation to deterministic generators of doublyexponential size and exponential longest distance, show both of these bounds to be optimal, and prove the corresponding games to be Expspace. Finally, we show tightness of the doubleexponential bound on the size as well as the longest distance for deterministic generators for Ltl even in the absence of next and until modalities. This research was partially supported by NSF Career award CCR9734115, NSF award CCR9970925, SRC award 99TJ688, and Alfred P. Sloan Faculty Fellowship. y Partially supported by the M.U.R.S.T. in the framework of project TO...
Model Checking Vs. Generalized Model Checking: Semantic Minimizations for Temporal Logics
 In Proceedings of the Twentieth Annual IEEE Symposium on Logic in Computer Science
, 2005
"... Threevalued models, in which properties of a system are either true, false or unknown, have recently been advocated as a better representation for reactive program abstractions generated by automatic techniques such as predicate abstraction. Indeed, for the same cost, model checking threevalued ab ..."
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Cited by 19 (10 self)
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Threevalued models, in which properties of a system are either true, false or unknown, have recently been advocated as a better representation for reactive program abstractions generated by automatic techniques such as predicate abstraction. Indeed, for the same cost, model checking threevalued abstractions can be used to both prove and disprove any temporallogic property, whereas traditional conservative abstractions can only prove universal properties. Also, verification results can be more precise with generalized model checking, which checks whether there exists a concretization of an abstraction satisfying a temporallogic formula. Since generalized model checking includes satisfiability as a special case (when everything in the model is unknown), it is in general more expensive than traditional model checking. In this paper, we study how to reduce generalized model checking to model checking by a temporallogic formula transformation, which generalizes a transformation for propositional logic known as semantic minimization in the literature. We show that many temporallogic formulas of practical interest are selfminimizing, i.e., are their own semantic minimizations, and hence that model checking for these formulas has the same precision as generalized model checking. 1
Past is for free: on the complexity of verifying linear temporal properties with past
 In Proceedings of the International Workshop on Expressiveness in Concurrency (EXPRESS’2002), volume 68.2 of Electronic Notes in Theoretical Computer Science. Elsevier Science
, 2002
"... We study the complexity of satisfiability and modelchecking of the lineartime temporal logic with past (pltl). More precisely, we consider several fragments of pltl, depending on the allowed set of temporal modalities, the use of negations or the nesting of future formulae into past formulae. Our ..."
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Cited by 15 (1 self)
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We study the complexity of satisfiability and modelchecking of the lineartime temporal logic with past (pltl). More precisely, we consider several fragments of pltl, depending on the allowed set of temporal modalities, the use of negations or the nesting of future formulae into past formulae. Our results show that "past is for free", that is it does not bring additional theoretical complexity, even for small fragments, and even when nesting future formulae into past formulae. We also remark that existential and universal modelchecking can have different complexity for certain fragments.
Hybrid logics on linear structures: Expressivity and complexity
 In Proceedings TIME 2003
, 2003
"... We investigate expressivity and complexity of hybrid logics on linear structures. Hybrid logics are an enrichment of modal logics with certain firstorder features which are algorithmically well behaved. Therefore, they are well suited for the specification of certain properties of computational sys ..."
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Cited by 14 (4 self)
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We investigate expressivity and complexity of hybrid logics on linear structures. Hybrid logics are an enrichment of modal logics with certain firstorder features which are algorithmically well behaved. Therefore, they are well suited for the specification of certain properties of computational systems. We show that hybrid logics are more expressive than usual modal and temporal logics on linear structures, and exhibit a hierarchy of hybrid languages. We determine the complexities of the satisfiability problem for these languages and define an existential fragment of hybrid logic for which satisfiability is still NPcomplete. Finally, we examine the linear time model checking problem for hybrid logics and its complexity. 1
Is your Model Checker on Time?  On the Complexity of Model Checking for Timed Modal Logics
, 2001
"... This paper studies the structural complexity of model checking for several timed modal logics presented in the literature. More precisely, we consider (variations on) the specification formalisms used in the tools CMC and Uppaal, and fragments of a timed calculus. For each of the logics, we charact ..."
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Cited by 14 (6 self)
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This paper studies the structural complexity of model checking for several timed modal logics presented in the literature. More precisely, we consider (variations on) the specification formalisms used in the tools CMC and Uppaal, and fragments of a timed calculus. For each of the logics, we characterize the computational complexity of model checking, as well as its specification and program complexity, using (parallel compositions of) timed automata as our system model. In particular, we show that the complexity of model checking for a timed calculus interpreted over (networks of) timed automata is EXPTIMEcomplete, no matter whether the complexity is measured with respect to the size of the specification, of the model or of both. All the flavours of model checking for timed versions of HennessyMilner logic, and the restricted fragments of the timed µcalculus studied in the literature on CMC and Uppaal, are shown to be PSPACEcomplete or EXPTIMEcomplete. Amongst the complexity results o ered in the paper is a theorem to the effect that the model checking problem for the sublanguage L s of the timed calculus, proposed by Larsen, Pettersson and Yi, is PSPACEcomplete. This result is accompanied by an array of statements showing that any extension of L s has an EXPTIMEcomplete model checking problem. We also argue that the model checking problem for the timed propositional µcalculus T is EXPTIMEcomplete, thus improving upon results by Henzinger, Nicollin, Sifakis and Yovine.