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Pushdown Processes: Games and Model Checking
, 1996
"... Games given by transition graphs of pushdown processes are considered. It is shown that ..."
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Cited by 136 (4 self)
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Games given by transition graphs of pushdown processes are considered. It is shown that
Modeling Concurrency with Geometry
, 1991
"... The phenomena of branching time and true or noninterleaving concurrency find their respective homes in automata and schedules. But these two models of computation are formally equivalent via Birkhoff duality, an equivalence we expound on here in tutorial detail. So why should these phenomena prefer ..."
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Cited by 125 (13 self)
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The phenomena of branching time and true or noninterleaving concurrency find their respective homes in automata and schedules. But these two models of computation are formally equivalent via Birkhoff duality, an equivalence we expound on here in tutorial detail. So why should these phenomena prefer one home over the other? We identify dimension as the culprit: 1dimensional automata are skeletons permitting only interleaving concurrency, whereas true nfold concurrency resides in transitions of dimension n. The truly concurrent automaton dual to a schedule is not a skeletal distributive lattice but a solid one. We introduce true nondeterminism and define it as monoidal homotopy; from this perspective nondeterminism in ordinary automata arises from forking and joining creating nontrivial homotopy. The automaton dual to a poset schedule is simply connected whereas that dual to an event structure schedule need not be, according to monoidal homotopy though not to group homotopy. We conclude...
Bisimulation Equivalence is Decidable for all ContextFree Processes
 Information and Computation
, 1995
"... Introduction Over the past decade much attention has been devoted to the study of process calculi such as CCS, ACP and CSP [13]. Of particular interest has been the study of the behavioural semantics of these calculi as given by labelled transition graphs. One important question is when processes c ..."
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Cited by 92 (15 self)
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Introduction Over the past decade much attention has been devoted to the study of process calculi such as CCS, ACP and CSP [13]. Of particular interest has been the study of the behavioural semantics of these calculi as given by labelled transition graphs. One important question is when processes can be said to exhibit the same behaviour, and a plethora of behavioural equivalences exists today. Their main rationale has been to capture behavioural aspects that language or trace equivalences do not take into account. The theory of finitestate systems and their equivalences can now be said to be wellestablished. There are many automatic verification tools for their analysis which incorporate equivalence checking. Sound and complete equational theories exist for the various known equivalences, an elegant example is [18]. One may be led to wonder what the results will look like for infinitestate systems. Although language equivalence is decidable
Model Checking for ContextFree Processes
, 1992
"... We develop a modelchecking algorithm that decides for a given contextfree process whether it satisfies a property written in the alternationfree modal mucalculus. The central idea behind this algorithm is to raise the standard iterative modelchecking techniques to higher order: in contrast to t ..."
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Cited by 78 (8 self)
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We develop a modelchecking algorithm that decides for a given contextfree process whether it satisfies a property written in the alternationfree modal mucalculus. The central idea behind this algorithm is to raise the standard iterative modelchecking techniques to higher order: in contrast to the usual approaches, in which the set of formulas that are satisfied by a certain state are iteratively computed, our algorithm iteratively computes a property transformer for each state class of the finite process representation. These property transformers can then simply be applied to solve the modelchecking problem. The complexity of our algorithm is linear in the size of the system's representation and exponential in the size of the property being investigated.
Modal and Temporal Logics for Processes
, 1996
"... this paper have been presented at the 4th European Summer School in Logic, Language and Information, University of Essex, 1992; at the Tempus Summer School for Algebraic and Categorical Methods in Computer Science, Masaryk University, Brno, 1993; and the Summer School in Logic Methods in Concurrency ..."
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Cited by 71 (2 self)
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this paper have been presented at the 4th European Summer School in Logic, Language and Information, University of Essex, 1992; at the Tempus Summer School for Algebraic and Categorical Methods in Computer Science, Masaryk University, Brno, 1993; and the Summer School in Logic Methods in Concurrency, Aarhus University, 1993. I would like to thank the organisers and the participants of these summer schools, and of the Banff higher order workshop. I would also like to thank Julian Bradfield for use of his Tex tree constructor for building derivation trees and Carron Kirkwood, Faron Moller, Perdita Stevens and David Walker for comments on earlier drafts.
Actions Speak Louder than Words: Proving Bisimilarity for ContextFree Processes
, 1991
"... Baeten, Bergstra, and Klop (and later Caucal) have proved the remarkable result that bisimulation equivalence is decidable for irredundant contextfree grammars. In this paper we provide a much simpler and much more direct proof of this result using a tableau decision method involving goaldirec ..."
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Cited by 45 (9 self)
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Baeten, Bergstra, and Klop (and later Caucal) have proved the remarkable result that bisimulation equivalence is decidable for irredundant contextfree grammars. In this paper we provide a much simpler and much more direct proof of this result using a tableau decision method involving goaldirected rules. The decision procedure also provides the essential part of the bisimulation relation between two processes which underlies their equivalence. We also show how to obtain a sound and complete sequentbased equational theory for such processes from the tableau system and how one can extract what Caucal calls a fundamental relation from a successful tableau.
Chu spaces and their interpretation as concurrent objects
, 2005
"... A Chu space is a binary relation =  from a set A to an antiset X defined as a set which transforms via converse functions. Chu spaces admit a great many interpretations by virtue of realizing all small concrete categories and most large ones arising in mathematical and computational practice. Of pa ..."
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Cited by 21 (0 self)
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A Chu space is a binary relation =  from a set A to an antiset X defined as a set which transforms via converse functions. Chu spaces admit a great many interpretations by virtue of realizing all small concrete categories and most large ones arising in mathematical and computational practice. Of particular interest for computer science is their interpretation as computational processes, which takes A to be a schedule of events distributed in time, X to be an automaton of states forming an information system in the sense of Scott, and the pairs (a, x) in the =  relation to be the individual transcriptions of the making of history. The traditional homogeneous binary relations of transition on X and precedence on A are recovered as respectively the right and left residuals of the heterogeneous binary relation =  with itself. The natural algebra of Chu spaces is that of linear logic, made a process algebra by the process interpretation.
Constrained Properties, Semilinear Systems, and Petri Nets
 PROCEEDINGS OF CONCUR'96, VOLUME 1119 OF LNCS
, 1996
"... We investigate the verification problem of two classes of infinite state systems w.r.t. nonregular properties (i.e., nondefinable by finitestate !automata). The systems we consider are Petri nets as well as semilinear systems including pushdown systems and PA processes. On the other hand, we consi ..."
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Cited by 20 (0 self)
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We investigate the verification problem of two classes of infinite state systems w.r.t. nonregular properties (i.e., nondefinable by finitestate !automata). The systems we consider are Petri nets as well as semilinear systems including pushdown systems and PA processes. On the other hand, we consider properties expressible in the logic CLTL which is an extension of the lineartime temporal logic LTL allowing two kinds of constraints: pattern constraints using finitestate automata and counting constraints using Presburger arithmetics formulas. While the verification problem of CLTL is undecidable even for finitestate systems, we identify a fragment called CLTL2 for which the verification problem is decidable for pushdown systems as well as for Petri nets. This fragment is strictly more expressive than finitestate !automata. We show that, however, the verification problem of semilinear systems (PA processes in particular) is undecidable even w.r.t. LTL formulas. Therefore, we identify another fragment (a restriction of LTL extended with counting constraints) covering a significant class of properties and for which the verification problem is decidable for all PA processes.
PAM: A Process Algebra Manipulator
 In Proc. Third Workshop on Computer Aided Verification
, 1993
"... PAM is a general proof tool for process algebras. It allows users to define their own calculi and then perform algebraic style proofs in these calculi by directly manipulating process terms. The logic that PAM implements is equational logic plus recursion, with some features tailored to the parti ..."
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Cited by 17 (0 self)
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PAM is a general proof tool for process algebras. It allows users to define their own calculi and then perform algebraic style proofs in these calculi by directly manipulating process terms. The logic that PAM implements is equational logic plus recursion, with some features tailored to the particular requirements of process algebras. Equational reasoning is implemented by rewriting, while recursion is dealt with by induction. Proofs are constructed interactively, giving users the freedom to control the proof processes.
Regularity of BPASystems is Decidable
 In Proceedings of CONCUR’94, volume 836 of LNCS
, 1994
"... . It is decidable whether a system in Basic Process Algebra (BPA) is regular with respect to bisimulation semantics. Basic operators in BPA are alternative composition, sequential composition and guarded recursion. A system is regular if the interpretations of all process variables defined in the sy ..."
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Cited by 15 (0 self)
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. It is decidable whether a system in Basic Process Algebra (BPA) is regular with respect to bisimulation semantics. Basic operators in BPA are alternative composition, sequential composition and guarded recursion. A system is regular if the interpretations of all process variables defined in the system have finitely many states. We present an effective method to transform a BPA specification into a linear specification whenever possible. 1 Introduction An important issue in automatic verification of concurrent systems using process algebra is extending the techniques to systems with an infinite state space. The simplest extension of regular specifications is BPA (Basic Process Algebra [3]), which has operators for alternative and sequential composition and allows for the construction of infinite processes by means of guarded recursion. The languages generated by BPA specifications are exactly the contextfree languages. However, we will not study language equivalence, but bisimulation...