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Tile Bisimilarity Congruences for Open Terms and Term Graphs
 in: Proc. CONCUR 2000, LNCS 1877 (2000
, 2000
"... The definition of sos formats ensuring that bisimilarity on closed terms is a congruence has received much attention in the last two decades. For dealing with open system specifications, the congruence is usually lifted from closed terms to open terms by instantiating the free variables in all possi ..."
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Cited by 13 (7 self)
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The definition of sos formats ensuring that bisimilarity on closed terms is a congruence has received much attention in the last two decades. For dealing with open system specifications, the congruence is usually lifted from closed terms to open terms by instantiating the free variables in all possible ways; the only alternatives considered in the literature relying on Larsen and Xinxin's context systems and Rensink's conditional transition systems. We propose a different approach based on tile logic, where both closed and open terms are managed analogously. In particular, we analyze the `bisimilarity as congruence' property for several tile formats that accomplish di erent concepts of subterm sharing.
SOS formats and metatheory: 20 years after
, 2007
"... In 1981 Structural Operational Semantics (SOS) was introduced as a systematic way to define operational semantics of programming languages by a set of rules of a certain shape [G.D. Plotkin, A structural approach to operational semantics, Technical ..."
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Cited by 11 (5 self)
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In 1981 Structural Operational Semantics (SOS) was introduced as a systematic way to define operational semantics of programming languages by a set of rules of a certain shape [G.D. Plotkin, A structural approach to operational semantics, Technical
Congruence for SOS with data
 In Proceedings of LICS’04
, 2004
"... While studying the specification of the operational semantics of different programming languages and formalisms, one can observe the following three facts. Firstly, Plotkin’s style of Structured Operational Semantics (SOS) has become a standard in defining operational semantics. Secondly, congruence ..."
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Cited by 9 (4 self)
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While studying the specification of the operational semantics of different programming languages and formalisms, one can observe the following three facts. Firstly, Plotkin’s style of Structured Operational Semantics (SOS) has become a standard in defining operational semantics. Secondly, congruence with respect to some notion of bisimilarity is an interesting property for such languages and it is essential in reasoning about them. Thirdly, there are numerous languages that contain an explicit data part in the state of the operational semantics. The first two facts, have resulted in a line of research exploring syntactic formats of operational rules to derive the desired congruence property for free. However, the third point (in combination with the first two) is not sufficiently addressed and there is no standard congruence format for operational semantics with an explicit data state. In this paper, we address this problem by studying the implications of the presence of a data state on the notion of bisimilarity. Furthermore, we propose a number of formats for congruence. 1
An Interactive Semantics of Logic Programming
 THEORY AND PRACTICE OF LOGIC PROGRAMMING
, 2001
"... We apply to logic programming some recently emerging ideas from the field of reductionbased communicating systems, with the aim of giving evidence of the hidden interactions and the coordination mechanisms that rule the operational machinery of such a programming paradigm. The semantic framework we ..."
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Cited by 8 (6 self)
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We apply to logic programming some recently emerging ideas from the field of reductionbased communicating systems, with the aim of giving evidence of the hidden interactions and the coordination mechanisms that rule the operational machinery of such a programming paradigm. The semantic framework we have chosen for presenting our results is tile logic, which has the advantage of allowing a uniform treatment of goals and observations and of applying abstract categorical tools for proving the results. As main contributions, we mention the finitary presentation of abstract unification, and a concurrent and coordinated abstract semantics consistent with the most common semantics of logic programming. Moreover, the compositionality of the tile semantics is guaranteed by standard results, as it reduces to check that the tile systems associated to logic programs enjoy the tile decomposition property. An extension of the approach for handling constraint systems is also discussed.
Open Ended Systems, Dynamic Bisimulation and Tile Logic
, 2000
"... The sos formats ensuring that bisimilarity is a congruence often fail in the presence of structural axioms on the algebra of states. Dynamic bisimulation, introduced to characterize the coarsest congruence for ccs which is also a (weak) bisimulation, reconciles the bisimilarity as congruence pro ..."
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Cited by 8 (4 self)
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The sos formats ensuring that bisimilarity is a congruence often fail in the presence of structural axioms on the algebra of states. Dynamic bisimulation, introduced to characterize the coarsest congruence for ccs which is also a (weak) bisimulation, reconciles the bisimilarity as congruence property with such axioms and with the specication of open ended systems, where states can be recongured at runtime, at the cost of an innitary operation at the metalevel. We show that the compositional framework oered by tile logic is suitable to deal with structural axioms and open ended systems specications, allowing for a nitary presentation of context closure. Keywords: Bisimulation, sos formats, dynamic bisimulation, tile logic. Introduction The semantics of dynamic systems can be conveniently expressed via labelled transition systems (lts) whose states are terms over a certain algebra and whose labels describe some abstract behavioral information. Provided such informatio...
A Hierarchy of SOS Rule Formats
, 2005
"... In 1981 Structural Operational Semantics (SOS) was introduced as a systematic way to define operational semantics of programming languages by a set of rules of a certain shape [62]. Subsequently, the format of SOS rules became the object of study. Using socalled Transition System Specifications (TS ..."
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Cited by 6 (1 self)
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In 1981 Structural Operational Semantics (SOS) was introduced as a systematic way to define operational semantics of programming languages by a set of rules of a certain shape [62]. Subsequently, the format of SOS rules became the object of study. Using socalled Transition System Specifications (TSS’s) several authors syntactically restricted the format of rules and showed several useful properties about the semantics induced by any TSS adhering to the format. This has resulted in a line of research proposing several syntactical rule formats and associated metatheorems. Properties that are guaranteed by such rule formats range from welldefinedness of the operational semantics and compositionality of behavioral equivalences to security and probabilityrelated issues. In this paper, we provide an initial hierarchy of SOS rules formats and metatheorems formulated around them.
Concurrent constraint programming with process mobility
 In Proc. of the CL 2000, LNAI
, 2000
"... Abstract. We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a “pure ” paradigm for process migration, namely a paradigm where the only actions are those d ..."
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Abstract. We propose an extension of concurrent constraint programming with primitives for process migration within a hierarchical network, and we study its semantics. To this purpose, we first investigate a “pure ” paradigm for process migration, namely a paradigm where the only actions are those dealing with transmissions of processes. Our goal is to give a structural definition of the semantics of migration; namely, we want to describe the behaviour of the system, during the transmission of a process, in terms of the behaviour of the components. We achieve this goal by using a labeled transition system where the effects of sending a process, and requesting a process, are modeled by symmetric rules (similar to handshakingrules for synchronous communication) between the two partner nodes in the network. Next, we extend our paradigm with the primitives of concurrent constraint programming, and we show how to enrich the semantics to cope with the notions of environment and constraint store. Finally, we show how the operational semantics can be used to define an interpreter for the basic calculus. 1
A format for semantic equivalence comparison
, 2003
"... This paper presents a new format for process algebras, the extended tyft/tyxt format which generalises the tyft/tyxt format of Groote and Vaandrager. The format di ers from most previous formats in that the labels on transitions are treated as manysorted terms. Bisimulation is a congruence for all ..."
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Cited by 2 (0 self)
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This paper presents a new format for process algebras, the extended tyft/tyxt format which generalises the tyft/tyxt format of Groote and Vaandrager. The format di ers from most previous formats in that the labels on transitions are treated as manysorted terms. Bisimulation is a congruence for all operators de ned by extended transition system speci cations in this format. When one extended transition system speci cation is summed with another, the resulting bisimulation can either identify more terms (an abstracting extension up to bisimulation) or fewer terms (a re ning extension up to bisimulation) than the original bisimulation on the individual system. The notions of abstracting extension and re ning extension are de ned, and two theorems are presented giving conditions required for achieving each type of extension. These results provide a way to compare di erent semantic equivalences de ned for di erent process algebras. Finally, an application of this theory to semantic equivalence comparison is given for a new result relating Castellani’s pomset equivalence and Krishnan’s multiprocessor equivalence.
SOS for Higher Order Processes (Extended Abstract)
"... Abstract. We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order processes. Then, we propose a number of extensions to Bernstein’s promoted tyft/tyxt format which aims at proving congruence of strong bisimilarity for higher order processes. The extended format ..."
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Abstract. We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order processes. Then, we propose a number of extensions to Bernstein’s promoted tyft/tyxt format which aims at proving congruence of strong bisimilarity for higher order processes. The extended format is called promoted PANTH. This format is easier to apply and strictly more expressive than the promoted tyft/tyxt format. Furthermore, we propose and prove a congruence format for a notion of higher order bisimilarity arising naturally from our SOS framework. To illustrate our formats, we apply them to Thomsen’s Calculus
Abstract Algebraic results for structured operational semantics
"... This paper presents algebraic results that are important for the extended tyft/tyxt format [12, 13] which can be used to describe many different process algebras. This format is based on a manysorted signature which permits both processes and labels to be treated syntactically. Existing results for ..."
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This paper presents algebraic results that are important for the extended tyft/tyxt format [12, 13] which can be used to describe many different process algebras. This format is based on a manysorted signature which permits both processes and labels to be treated syntactically. Existing results for this format permit the comparison of process algebra semantic equivalences by forming the sum of two transition system specifications and imposing certain conditions. The results presented in this paper involve the summing of congruences that model the actual process algebra labels, and determine under what conditions these congruences have important properties such as compatibility and conservativity. The aim of this paper is to show that the notion of sortsimilarity on the sum of signatures is sufficient for the sum of the congruences induced by each label algebra to be the same as the congruence induced by the summed label algebras. Additionally, sortsimilarity is sufficient for compatibility and conservativity when summing. Finally, conditions on the label algebra are given that ensure compatibility.