Results 1  10
of
30
Forward and Backward Simulations Part I: Untimed Systems
 Information and Computation
, 1995
"... A unified, comprehensive presentation of simulation techniques for verification of concurrent systems is given, in terms of a simple untimed automaton model. In particular, (1) refinements, (2) forward and backward simulations, (3) hybrid forwardbackward and backwardforward simulations, and (4) hi ..."
Abstract

Cited by 134 (18 self)
 Add to MetaCart
A unified, comprehensive presentation of simulation techniques for verification of concurrent systems is given, in terms of a simple untimed automaton model. In particular, (1) refinements, (2) forward and backward simulations, (3) hybrid forwardbackward and backwardforward simulations, and (4) history and prophecy relations are defined. History and prophecy relations are abstract versions of the history and prophecy variables of Abadi and Lamport, as well as the auxiliary variables of Owicki and Gries. Relationships between the different types of simulations, as well as soundness and completeness results, are stated and proved. Finally, it is shown how invariants can be incorporated into all the simulations. Even though many results are presented here for the first time, this paper can also be read as a survey (in a simple setting) of the research literature on simulation techniques. The development for untimed automata is designed to support a similar development for timed automata...
TimeConstrained Automata
 CONCUR '91: 2nd International Conference on Concurrency Theory, volume 527 of Lecture Notes in Computer Science
, 1991
"... ) Michael Merritt AT&T Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974 merritt@research.att.com Francesmary Modugno School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 fmm@cs.cmu.edu Mark R. Tuttle DEC Cambridge Research Lab One Kendall Sq., Bldg. 700 Camb ..."
Abstract

Cited by 83 (0 self)
 Add to MetaCart
) Michael Merritt AT&T Bell Laboratories 600 Mountain Avenue Murray Hill, NJ 07974 merritt@research.att.com Francesmary Modugno School of Computer Science Carnegie Mellon University Pittsburgh, PA 15213 fmm@cs.cmu.edu Mark R. Tuttle DEC Cambridge Research Lab One Kendall Sq., Bldg. 700 Cambridge, MA 02139 tuttle@crl.dec.com Abstract In this paper, we augment the inputoutput automaton model in order to reason about time in concurrent systems, and we prove simple properties of this augmentation. The inputoutput automata model is a useful model for reasoning about computation in concurrent and distributed systems because it allows fundamental properties such as fairness and compositionality to be expressed easily and naturally. A unique property of the model is that systems are modeled as the composition of autonomous components. This paper describes a way to add a notion of time to the model in a way that preserves these properties. The result is a simple, compositional model fo...
Forward and backward simulations for timingbased systems
 In de Bakker et al
, 1991
"... A general automaton model for timingbased systems is presented and is used as the context for developing a variety of simulation proof techniques for such systems. As a first step, a comprehensive overview of simulation techniques for simple untimed automata is given. In particular, soundness and ..."
Abstract

Cited by 63 (16 self)
 Add to MetaCart
A general automaton model for timingbased systems is presented and is used as the context for developing a variety of simulation proof techniques for such systems. As a first step, a comprehensive overview of simulation techniques for simple untimed automata is given. In particular, soundness and completeness results for (1) refinements, (2) forward and backward simulations, (3) forwardbackward and backwardforward simulations, and (4) history and prophecy relations are given. History and prophecy relations are new and are abstractions of the history variables of Owicki and Gries and the prophecy variables of Abadi and Lamport, respectively. As a subsequent step, it is shown how most of the results for untimed automata can be carried over to the setting of timed automata. In fact, many of the results for the timed case are obtained as consequences of the analogous results for the untimed case.
The Anchored Version of the Temporal Framework
 Linear Time, Branching Time, and Partial Order in Logics and Models for Concurrency, Lecture Notes in Computer Science 354
, 1989
"... . In this survey paper we present some of the recent developments in the temporal formal system for the specification, verification and development of reactive programs. While the general methodology remains very much the one presented in some earlier works on the subject, such as [MP83c, MP83a, Pnu ..."
Abstract

Cited by 50 (5 self)
 Add to MetaCart
. In this survey paper we present some of the recent developments in the temporal formal system for the specification, verification and development of reactive programs. While the general methodology remains very much the one presented in some earlier works on the subject, such as [MP83c, MP83a, Pnu86], there have been several technical improvements and gained insights in understanding the computational model, the logic itself, the proof system and its presentation, and connections with alternative formalisms, such as finite automata. In this paper we explicate some of these improvements and extensions. The main difference between this and preceding versions is that here we consider a notion of validity for temporal formulae, which is anchored at the initial state of the computation. The paper discusses some of the consequences of this decision. Key words: Temporal Logic, Reactive Systems, Concurrent Programs, Specification, Verification, Proof System, Classification of Prtoperties, Sa...
Computations, residuals and the power of indeterminacy
 In Timo Lepisto and Arto Salomaa, editors, Proceedings of the Fifteenth ICALP
, 1988
"... We investigate the power of Katmstyle datattow networks, with processes that may exhibit indeterminate behavior. Our main result is a theorem about networks of "monotone " processes, which shows: (1) that the input/output relation of such a network is a total and monotone relation; and (2 ..."
Abstract

Cited by 20 (10 self)
 Add to MetaCart
We investigate the power of Katmstyle datattow networks, with processes that may exhibit indeterminate behavior. Our main result is a theorem about networks of "monotone " processes, which shows: (1) that the input/output relation of such a network is a total and monotone relation; and (2) every relation that is total, monotone, and continuous in a certain sense, is the input/output relation of such a network. Now, the class of monotone networks includes networks that compute arbitrary continuous inpu*~/output functions, an "angelic merge " network, and an "ilffinityfair merge " network that exhibits countably indeterminate branching. Since the "fair merge " relation is neither monotone nor continuous, a corollary of our main result is the impossibility of implementing fair merge in terms of continuous functions, angelic merge, and infinityfair merge. Our results are established by applying the powerftll technique of "residuals " to the computations of a network. Residuals, which have previously been used to investigate optimal reduction strategies for the Acalculus, have recently been demonstrated by one of the authors (Stark) "also to be of use in reasoning about concurrent systems. Here, we define the general notion of a "residual operation " on an automaton, and show how residual operations defined on the components of a network induce a certain preorder E on the set of computations of the network. For networks of "monotone port automata, " we show that the "fair " computations coincide with Xmaximal computations. Our results follow from this extremely convenient property. 1
A theorem on atomicity in distributed algorithms
 Distributed Computing
, 1990
"... work may not be copied or reproduced in whole or in part for any commercial ..."
Abstract

Cited by 13 (0 self)
 Add to MetaCart
work may not be copied or reproduced in whole or in part for any commercial
A Complete Proof System for QPTL
 In Proceedings, Tenth Annual IEEE Symposium on Logic in Computer Science
, 1995
"... Abstract The paper presents an axiomatic system for quantified propositional temporal logic (qptl), which is propositional temporal logic equipped with quantification over propositions (boolean variables). The advantages of this extended temporal logic is that its expressive power is strictly highe ..."
Abstract

Cited by 12 (0 self)
 Add to MetaCart
Abstract The paper presents an axiomatic system for quantified propositional temporal logic (qptl), which is propositional temporal logic equipped with quantification over propositions (boolean variables). The advantages of this extended temporal logic is that its expressive power is strictly higher than that of the unquantified version (ptl) and is equal to that of S1S, as well as that of !automata. Another important application of qptl is its use for formulating and verifying refinement relations between reactive systems. In fact, the completeness proof is based on the reduction of a qptl formula into a Buchi automaton, and performing equivalence transformations on this automata, formally justifying these transformations. 1 Introduction For a long time, temporal logics have been mainly used for the specification and verification of properties of reactive systems. According to this approach, a system is specified by a list of properties, all of which should be satisfied by any acc...
Team Automata Satisfying Compositionality
 Proc. FM 2003, in: Lecture Notes in Comput. Sci
, 2003
"... A team automaton is said to satisfy compositionality if its behaviour can be described in terms of the behaviour of its constituting component automata. As an initial investigation of the conditions under which team automata satisfy compositionality, we study their computations and behaviour in ..."
Abstract

Cited by 12 (4 self)
 Add to MetaCart
A team automaton is said to satisfy compositionality if its behaviour can be described in terms of the behaviour of its constituting component automata. As an initial investigation of the conditions under which team automata satisfy compositionality, we study their computations and behaviour in relation to those of their constituting component automata. We show that the construction of team automata according to certain natural types of synchronization guarantees compositionality.
Formal Verification of TCP and T/TCP
, 1997
"... In this thesis we present a formal abstract specification for TCP/IP transport level protocols and formally verify that TCP satisfies this specification. We first verify a formal model of TCP where we assume it has unbounded counters. With bounded counters, TCP requires several timing mechanisms to ..."
Abstract

Cited by 9 (1 self)
 Add to MetaCart
In this thesis we present a formal abstract specification for TCP/IP transport level protocols and formally verify that TCP satisfies this specification. We first verify a formal model of TCP where we assume it has unbounded counters. With bounded counters, TCP requires several timing mechanisms to function correctly. We also model TCP with these timing mechanisms and verify that it also satisfies our specification. We also present a formal description of an experimental protocol called T/TCP which is designed to provide the same service as TCP, but with optimizations to make it efficient for transactions. Even with unbounded counters this protocol does not provide the same service as TCP as it may deliver the same message twice. Even though the service provide by T/TCP is not exactly the same as TCP, its behavior may be acceptable for some applications. Therefore, we define a weaker specification that captures this behavior of T/TCP while maintaining the other correctness properties of our initial specification. We then verify that T/TCP satisfies this weaker specification. Our