Luca Aceto - Academia.edu (original) (raw)
Papers by Luca Aceto
BRICS Report Series, 1999
Fifth Ifip International Conference On Theoretical Computer Science – Tcs 2008, 2008
We investigate the equational theory of several fragments of CCS modulo (strong) bisimilarity wit... more We investigate the equational theory of several fragments of CCS modulo (strong) bisimilarity with special attention to restriction and relabelling. The largest fragment we consider includes action prefixing, choice, parallel composition without communication, restriction and relabelling. We present a finite equational base (i.e., a finite ground-complete and omega-complete axiomatisation) for it, including the left merge from ACP as auxiliary operation to facilitate the axiomatisation of parallel composition.
Lecture Notes in Computer Science, 1998
The computational engine of the veriÿcation tool UPPAAL consists of a collection of e cient algor... more The computational engine of the veriÿcation tool UPPAAL consists of a collection of e cient algorithms for the analysis of reachability properties of systems. Model-checking of properties other than plain reachability ones may currently be carried out in such a tool as follows. Given a property to model-check, the user must provide a test automaton T for it. This test automaton must be such that the original system S has the property expressed by precisely when none of the distinguished reject states of T can be reached in the synchronized parallel composition of S with T. This raises the question of which properties may be analysed by UPPAAL in such a way. This paper gives an answer to this question by providing a complete characterization of the class of properties for which model-checking can be reduced to reachability testing in the sense outlined above. This result is obtained as a corollary of a stronger statement pertaining to the compositionality of the property language considered in this study. In particular, it is shown * Corresponding author.
Lecture Notes in Computer Science, 1998
Prefix iteration is a variation on the original binary version of the Kleene star operation P* Q,... more Prefix iteration is a variation on the original binary version of the Kleene star operation P* Q, obtained by restricting the first argument to be an atomic action, and yields simple iterative behaviours that can be equationally characterized by means of finite collections of axioms. In this paper, we present axiomatic characterizations for a significant fragment of the notions of equivalence and preorder in van Glabbeek's linear-time/branching-time spectrum over Milner's basic CCS extended with prefix iteration. More precisely, we consider ready simulation, simulation, readiness, trace and language semantics, and provide complete (in)equational axiomatizations for each of these notions over BCCS with prefix iteration. All of the axiom systems we present are finite, if so is the set of atomic actions under consideration.
Electronic Proceedings in Theoretical Computer Science, 2010
This paper presents a bisimulation-based method for establishing the soundness of equations betwe... more This paper presents a bisimulation-based method for establishing the soundness of equations between terms constructed using operations whose semantics is specified by rules in the GSOS format of Bloom, Istrail and Meyer. The method is inspired by de Simone's FH-bisimilarity and uses transition rules as schematic transitions in a bisimulation-like relation between open terms. The soundness of the method is proven and examples showing its applicability are provided. The proposed bisimulation-based proof method is incomplete, but the article offers some completeness results for restricted classes of GSOS specifications. An extension of the proof method to the setting of GSOS languages with predicates is also offered.
Lecture Notes in Computer Science, 2001
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Lecture Notes in Computer Science, 2012
This paper presents a complete account of positive and negative results on the finite axiomatizab... more This paper presents a complete account of positive and negative results on the finite axiomatizability of weak complete simulation semantics over the language BCCSP. We offer finite (un)conditional groundcomplete axiomatizations for the weak complete simulation precongruence. In sharp contrast to this positive result, we prove that, in the presence of at least one observable action, the (in)equational theory of the weak complete simulation precongruence over BCCSP does not have a finite (in)equational basis. In fact, the collection of (in)equations in at most one variable that hold in weak complete simulation semantics over BCCSP does not have an (in)equational basis of 'bounded depth', let alone a finite one.
Formal methods is the term used to describe the specification and verification of software and so... more Formal methods is the term used to describe the specification and verification of software and software systems using mathematical logic. Various methodologies have been developed and incorporated into software tools. An important subclass is distributed systems. There are many books that look at particular methodologies for such systems, e.g. CSP, process algebra. This book offers a more balanced introduction for graduate students that describes the various approaches, their strengths and weaknesses, and when they are best used. Milner's CCS and its operational semantics are introduced, together with notions of behavioural equivalence based on bisimulation techniques and with variants of Hennessy-Milner modal logics. Later in the book, the presented theories are extended to take timing issues into account. The book has arisen from various courses taught in Iceland and Denmark and is designed to give students a broad introduction to the area, with exercises throughout.
Lecture Notes in Computer Science, 2012
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
Electronic Proceedings in Theoretical Computer Science, 2011
In this paper, we introduce an extension of the GSOS rule format with predicates such as terminat... more In this paper, we introduce an extension of the GSOS rule format with predicates such as termination, convergence and divergence. For this format we generalize the technique proposed by Aceto, Bloom and Vaandrager for the automatic generation of ground-complete axiomatizations of bisimilarity over GSOS systems. Our procedure is implemented in a tool that receives SOS specifications as input and derives the corresponding axiomatizations automatically. This paves the way to checking strong bisimilarity over process terms by means of theorem-proving techniques.
Theoretical Computer Science, 2014
This paper is devoted to the study of the (in)equational theory of the largest (pre)congruences o... more This paper is devoted to the study of the (in)equational theory of the largest (pre)congruences over the language BCCSP induced by variations on the classic simulation preorder and equivalence that abstract from internal steps in process behaviours. In particular, the article focuses on the (pre)congruences associated with the weak simulation, the weak complete simulation and the weak ready simulation preorders. For each of these behavioural semantics, results on the (non)existence of finite (ground-)complete (in)equational axiomatizations are given. The axiomatization of those semantics using conditional equations is also discussed in some detail.
Theoretical Computer Science, 2006
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Theoretical Computer Science, 2005
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Science of Computer Programming, 2014
In this paper we propose an extension of the Rebeca language that can be used to model distribute... more In this paper we propose an extension of the Rebeca language that can be used to model distributed and asynchronous systems with timing constraints. We provide the formal semantics of the language using Structural Operational Semantics, and show its expressiveness by means of examples. We developed a tool for automated translation from timed Rebeca to the Erlang language, which provides a first implementation of timed Rebeca. We can use the tool to set the parameters of timed Rebeca models, which represent the environment and component variables, and use McErlang to run multiple simulations for different settings. Timed Rebeca restricts the modeller to a pure asynchronous actor-based paradigm, where the structure of the model represents the service oriented architecture, while the computational model matches the network infrastructure. Simulation is shown to be an effective analysis support, specially where model checking faces almost immediate state explosion in an asynchronous setting.
RAIRO - Theoretical Informatics and Applications, 2002
We show that the validity of Parikh's theorem for contextfree languages depends only on a few equ... more We show that the validity of Parikh's theorem for contextfree languages depends only on a few equational properties of least prefixed points. Moreover, we exhibit an infinite basis of µ-term equations of continuous commutative idempotent semirings.
Mathematical Structures in Computer Science, 1998
Fokkink and Zantema (Fokkink and Zantema 1994) have shown that bisimulation equivalence has a fin... more Fokkink and Zantema (Fokkink and Zantema 1994) have shown that bisimulation equivalence has a finite equational axiomatization over the language of Basic Process Algebra with the binary Kleene star operation (BPA*). In light of this positive result on the mathematical tractability of bisimulation equivalence over BPA*, a natural question to ask is whether any other (pre)congruence relation in van Glabbeek's linear time/branching time spectrum is finitely (in)equationally axiomatizable over it. In this paper, we prove that, unlike bisimulation equivalence, none of the preorders and equivalences in van Glabbeek's linear time/branching time spectrum, whose discriminating power lies in between that of ready simulation and that of completed traces, has a finite equational axiomatization. This we achieve by exhibiting a family of (in)equivalences that holds in ready simulation semantics (which is the finest semantics that we consider) and whose instances cannot all be proved by me...
Journal of the ACM, 1992
In this paper, a process algebra that incorporates explicit representations of successful termina... more In this paper, a process algebra that incorporates explicit representations of successful termination, deadlock, and divergence is introduced and its semantic theory is analyzed. Both an operational and a denotational semantics for the language is given and it is shown that they agree. The operational theory is based upon a suitable adaptation of the notion of bisimulation preorder. The denotational semantics for the language is given in terms of the initial continuous algebra that satisfies a set of equations E , CI E . It is shown that CI E is fully abstract with respect to our choice of behavioral preorder. Several results of independent interest are obtained; namely, the finite approximability of the behavioral preorder and a partial completeness result for the set of equations E with respect to the preorder.
Journal of Computer Science and Technology, 2004
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Information Processing Letters, 2011
This note shows that the complete and the ready simulation preorders do not have a finite inequat... more This note shows that the complete and the ready simulation preorders do not have a finite inequational basis over the language BCCSP when the set of actions is a singleton. Moreover, the equivalences induced by those preorders do not have a finite (in)equational axiomatization either. These results are in contrast with a claim of finite axiomatizability for those semantics in the literature, which was based on the erroneous assumption that they coincide with complete trace semantics in the presence of a singleton set of actions.
BRICS Report Series, 1999
Fifth Ifip International Conference On Theoretical Computer Science – Tcs 2008, 2008
We investigate the equational theory of several fragments of CCS modulo (strong) bisimilarity wit... more We investigate the equational theory of several fragments of CCS modulo (strong) bisimilarity with special attention to restriction and relabelling. The largest fragment we consider includes action prefixing, choice, parallel composition without communication, restriction and relabelling. We present a finite equational base (i.e., a finite ground-complete and omega-complete axiomatisation) for it, including the left merge from ACP as auxiliary operation to facilitate the axiomatisation of parallel composition.
Lecture Notes in Computer Science, 1998
The computational engine of the veriÿcation tool UPPAAL consists of a collection of e cient algor... more The computational engine of the veriÿcation tool UPPAAL consists of a collection of e cient algorithms for the analysis of reachability properties of systems. Model-checking of properties other than plain reachability ones may currently be carried out in such a tool as follows. Given a property to model-check, the user must provide a test automaton T for it. This test automaton must be such that the original system S has the property expressed by precisely when none of the distinguished reject states of T can be reached in the synchronized parallel composition of S with T. This raises the question of which properties may be analysed by UPPAAL in such a way. This paper gives an answer to this question by providing a complete characterization of the class of properties for which model-checking can be reduced to reachability testing in the sense outlined above. This result is obtained as a corollary of a stronger statement pertaining to the compositionality of the property language considered in this study. In particular, it is shown * Corresponding author.
Lecture Notes in Computer Science, 1998
Prefix iteration is a variation on the original binary version of the Kleene star operation P* Q,... more Prefix iteration is a variation on the original binary version of the Kleene star operation P* Q, obtained by restricting the first argument to be an atomic action, and yields simple iterative behaviours that can be equationally characterized by means of finite collections of axioms. In this paper, we present axiomatic characterizations for a significant fragment of the notions of equivalence and preorder in van Glabbeek's linear-time/branching-time spectrum over Milner's basic CCS extended with prefix iteration. More precisely, we consider ready simulation, simulation, readiness, trace and language semantics, and provide complete (in)equational axiomatizations for each of these notions over BCCS with prefix iteration. All of the axiom systems we present are finite, if so is the set of atomic actions under consideration.
Electronic Proceedings in Theoretical Computer Science, 2010
This paper presents a bisimulation-based method for establishing the soundness of equations betwe... more This paper presents a bisimulation-based method for establishing the soundness of equations between terms constructed using operations whose semantics is specified by rules in the GSOS format of Bloom, Istrail and Meyer. The method is inspired by de Simone's FH-bisimilarity and uses transition rules as schematic transitions in a bisimulation-like relation between open terms. The soundness of the method is proven and examples showing its applicability are provided. The proposed bisimulation-based proof method is incomplete, but the article offers some completeness results for restricted classes of GSOS specifications. An extension of the proof method to the setting of GSOS languages with predicates is also offered.
Lecture Notes in Computer Science, 2001
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Lecture Notes in Computer Science, 2012
This paper presents a complete account of positive and negative results on the finite axiomatizab... more This paper presents a complete account of positive and negative results on the finite axiomatizability of weak complete simulation semantics over the language BCCSP. We offer finite (un)conditional groundcomplete axiomatizations for the weak complete simulation precongruence. In sharp contrast to this positive result, we prove that, in the presence of at least one observable action, the (in)equational theory of the weak complete simulation precongruence over BCCSP does not have a finite (in)equational basis. In fact, the collection of (in)equations in at most one variable that hold in weak complete simulation semantics over BCCSP does not have an (in)equational basis of 'bounded depth', let alone a finite one.
Formal methods is the term used to describe the specification and verification of software and so... more Formal methods is the term used to describe the specification and verification of software and software systems using mathematical logic. Various methodologies have been developed and incorporated into software tools. An important subclass is distributed systems. There are many books that look at particular methodologies for such systems, e.g. CSP, process algebra. This book offers a more balanced introduction for graduate students that describes the various approaches, their strengths and weaknesses, and when they are best used. Milner's CCS and its operational semantics are introduced, together with notions of behavioural equivalence based on bisimulation techniques and with variants of Hennessy-Milner modal logics. Later in the book, the presented theories are extended to take timing issues into account. The book has arisen from various courses taught in Iceland and Denmark and is designed to give students a broad introduction to the area, with exercises throughout.
Lecture Notes in Computer Science, 2012
DOI to the publisher's website. • The final author version and the galley proof are versions of t... more DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal. If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the "Taverne" license above, please follow below link for the End User Agreement:
Electronic Proceedings in Theoretical Computer Science, 2011
In this paper, we introduce an extension of the GSOS rule format with predicates such as terminat... more In this paper, we introduce an extension of the GSOS rule format with predicates such as termination, convergence and divergence. For this format we generalize the technique proposed by Aceto, Bloom and Vaandrager for the automatic generation of ground-complete axiomatizations of bisimilarity over GSOS systems. Our procedure is implemented in a tool that receives SOS specifications as input and derives the corresponding axiomatizations automatically. This paves the way to checking strong bisimilarity over process terms by means of theorem-proving techniques.
Theoretical Computer Science, 2014
This paper is devoted to the study of the (in)equational theory of the largest (pre)congruences o... more This paper is devoted to the study of the (in)equational theory of the largest (pre)congruences over the language BCCSP induced by variations on the classic simulation preorder and equivalence that abstract from internal steps in process behaviours. In particular, the article focuses on the (pre)congruences associated with the weak simulation, the weak complete simulation and the weak ready simulation preorders. For each of these behavioural semantics, results on the (non)existence of finite (ground-)complete (in)equational axiomatizations are given. The axiomatization of those semantics using conditional equations is also discussed in some detail.
Theoretical Computer Science, 2006
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Theoretical Computer Science, 2005
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Science of Computer Programming, 2014
In this paper we propose an extension of the Rebeca language that can be used to model distribute... more In this paper we propose an extension of the Rebeca language that can be used to model distributed and asynchronous systems with timing constraints. We provide the formal semantics of the language using Structural Operational Semantics, and show its expressiveness by means of examples. We developed a tool for automated translation from timed Rebeca to the Erlang language, which provides a first implementation of timed Rebeca. We can use the tool to set the parameters of timed Rebeca models, which represent the environment and component variables, and use McErlang to run multiple simulations for different settings. Timed Rebeca restricts the modeller to a pure asynchronous actor-based paradigm, where the structure of the model represents the service oriented architecture, while the computational model matches the network infrastructure. Simulation is shown to be an effective analysis support, specially where model checking faces almost immediate state explosion in an asynchronous setting.
RAIRO - Theoretical Informatics and Applications, 2002
We show that the validity of Parikh's theorem for contextfree languages depends only on a few equ... more We show that the validity of Parikh's theorem for contextfree languages depends only on a few equational properties of least prefixed points. Moreover, we exhibit an infinite basis of µ-term equations of continuous commutative idempotent semirings.
Mathematical Structures in Computer Science, 1998
Fokkink and Zantema (Fokkink and Zantema 1994) have shown that bisimulation equivalence has a fin... more Fokkink and Zantema (Fokkink and Zantema 1994) have shown that bisimulation equivalence has a finite equational axiomatization over the language of Basic Process Algebra with the binary Kleene star operation (BPA*). In light of this positive result on the mathematical tractability of bisimulation equivalence over BPA*, a natural question to ask is whether any other (pre)congruence relation in van Glabbeek's linear time/branching time spectrum is finitely (in)equationally axiomatizable over it. In this paper, we prove that, unlike bisimulation equivalence, none of the preorders and equivalences in van Glabbeek's linear time/branching time spectrum, whose discriminating power lies in between that of ready simulation and that of completed traces, has a finite equational axiomatization. This we achieve by exhibiting a family of (in)equivalences that holds in ready simulation semantics (which is the finest semantics that we consider) and whose instances cannot all be proved by me...
Journal of the ACM, 1992
In this paper, a process algebra that incorporates explicit representations of successful termina... more In this paper, a process algebra that incorporates explicit representations of successful termination, deadlock, and divergence is introduced and its semantic theory is analyzed. Both an operational and a denotational semantics for the language is given and it is shown that they agree. The operational theory is based upon a suitable adaptation of the notion of bisimulation preorder. The denotational semantics for the language is given in terms of the initial continuous algebra that satisfies a set of equations E , CI E . It is shown that CI E is fully abstract with respect to our choice of behavioral preorder. Several results of independent interest are obtained; namely, the finite approximability of the behavioral preorder and a partial completeness result for the set of equations E with respect to the preorder.
Journal of Computer Science and Technology, 2004
See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained... more See back inner page for a list of recent BRICS Report Series publications. Copies may be obtained by contacting:
Information Processing Letters, 2011
This note shows that the complete and the ready simulation preorders do not have a finite inequat... more This note shows that the complete and the ready simulation preorders do not have a finite inequational basis over the language BCCSP when the set of actions is a singleton. Moreover, the equivalences induced by those preorders do not have a finite (in)equational axiomatization either. These results are in contrast with a claim of finite axiomatizability for those semantics in the literature, which was based on the erroneous assumption that they coincide with complete trace semantics in the presence of a singleton set of actions.