Observation and abstract behaviour in specification and implementation of state-based systems

Classical algebraic specification is an accepted framework for specification. A criticism which applies is the fact that it is functional, not based on a notion of state as most software development and implementation languages are. We formalise the idea of a state-based object or abstract machine using algebraic means. In contrast to similar approaches we consider dynamic logic instead of equational logic as the framework for specification and implementation. The advantage is a more expressive language allowing us to specify safety and liveness conditions. It also allows a clearer distinction of functional and state-based parts which require different treatment in order to achieve behavioural abstraction when necessary. We shall in particular focus on abstract behaviour and observation. A behavioural notion of satisfaction for state-elements is needed in order to abstract from irrelevant details of the state realisation

Closure properties for the class of behavioral models

Hidden k-logics can be considered as the underlying logics of program specification. They constitute natural generalizations of k-deductive systems and encompass deductive systems as well as hidden equational logics and inequational logics. In our abstract algebraic approach, the data structures are sorted algebras endowed with a designated subset of their visible parts, called filter, which represents a set of truth values. We present a hierarchy of classes of hidden k-logics. The hidden k-logics in each class are characterized by three different kinds of conditions, namely, properties of their Leibniz operators, closure properties of the class of their behavioral models, and properties of their equivalence systems. Using equivalence systems, we obtain a new and more complete analysis of the axiomatization of the behavioral models. This is achieved by means of the Leibniz operator and its combinatorial properties. © 2007 Elsevier Ltd. All rights reserved.FCT via UIM

Behavioural reasoning for conditional equations

Object-oriented (OO) programming techniques can be applied to equational specification logics by distinguishing visible data from hidden data (that is, by distinguishing the output of methods from the objects to which the methods apply), and then focusing on the behavioural equivalence of hidden data in the sense introduced by H. Reichel in 1984. Equational specification logics structured in this way are called hidden equational logics, HELs. The central problem is how to extend the specification of a given HEL to a specification of behavioural equivalence in a computationally effective way. S. Buss and G. Roşu showed in 2000 that this is not possible in general, but much work has been done on the partial specification of behavioural equivalence for a wide class of HELs. The OO connection suggests the use of coalgebraic methods, and J. Goguen and his collaborators have developed coinductive processes that depend on an appropriate choice of a cobasis, which is a special set of contexts that generates a subset of the behavioural equivalence relation. In this paper the theoretical aspects of coinduction are investigated, specifically its role as a supplement to standard equational logic for determining behavioural equivalence. Various forms of coinduction are explored. A simple characterisation is given of those HELs that are behaviourally specifiable. Those sets of conditional equations that constitute a complete, finite cobasis for a HEL are characterised in terms of the HEL's specification. Behavioural equivalence, in the form of logical equivalence, is also an important concept for single-sorted logics, for example, sentential logics such as the classical propositional logic. The paper is an application of the methods developed through the extensive work that has been done in this area on HELs, and to a broader class of logics that encompasses both sentential logics and HELs. © 2007 Cambridge University Press.FCT via UIM

Preface Volume 11

AbstractThis volume contains the Proceedings of the First Workshop on Coalgebraic Methods in Computer Science (CMCS '98). The Workshop was held in Lisbon, Portugal on March 28 and 29, 1998, as a satellite event to ETAPS '98.During the last decade, it has become increasingly clear that many state-based dynamical systems, such as transition systems, automata, and object-based systems, can be captured uniformly as coalgebras. Coalgebra is beginning to develop into a field of its own, with its own model theory and proof methods (involving bisimulations and invariants).The aim of this workshop is to bring together researchers with a common interest in the theory of coalgebra and its applications. We are very happy with both the number and the quality of the papers that were submitted, as well as with the fact that the Workshop has attracted many participants.The papers in this volume were reviewed by the organizers of the meeting. This series is published electronically through the facilities of Elsevier Science B.V. and under its auspices. A printed version of this volume is distributed to the participants of the Workshop.We are very grateful to the following persons, whose help has been crucial for the success of CMCS '98: Jose Fiardeiro, the organizer of ETAPS '98, for his help with the organization of the Workshop; Mike Mislove, one of the Managing Editors of the ENTCS series, for his assistence with the use of the ENTCS style files; and Jan Schipper, from the Facility Department of CWI, for his help in printing these Proceedings. Thanks are also due to the Department of Software Engineering (SEN) of the CWI, which has supplied financial support for the printing costs.10 March 1998, Bart Jacobs, Larry Moss, Horst Reichel, Jan Rutte

Programming Languages and Systems

This open access book constitutes the proceedings of the 31st European Symposium on Programming, ESOP 2022, which was held during April 5-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 21 regular papers presented in this volume were carefully reviewed and selected from 64 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Transparent synchronous dataflow: a functional paradigm for systems modelling and optimisation

System modelling is the use of mathematical formalisms to model real world systems for the purpose of analysis, simulation and prediction. One of the most common ways to model a system is to create the dataflow among its various components. There are two main approaches on how dataflow graphs are constructed in these system modelling frameworks: ‘define-and-run’ vs ‘define-by-run’. The former approach first creates a dataflow graph and then executes it by pushing data into it. The latter however constructs the graph while computing with data on-the-fly. ‘Define-and-run’ is usually more efficient because many graph optimisations can be applied; ‘Define-by-run’ however handles dynamic models better. This thesis aims to develop a new functional paradigm for systems modelling and optimisation that exhibits properties of both approaches where dataflow graphs are dynamic but efficient. We propose a new functional language, namely transparent synchronous dataflow (TSD), where dataflow graphs are constructed transparently with imperative commands to manipulate them explicitly; together with a synchronous mode of change propagation. The semantics of the language is designed on top of an unconventional graph abstract machine, Dynamic Geometry of Interaction Machine (DGoIM), which is natural for manipulating dataflow graphs. By using this semantics, the language is proved to be sound and efficient. Several experimental implementations were also created, including a native compiler for DGoIM and OCaml implementations for TSD

Programming Languages and Systems

This open access book constitutes the proceedings of the 31st European Symposium on Programming, ESOP 2022, which was held during April 5-7, 2022, in Munich, Germany, as part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2022. The 21 regular papers presented in this volume were carefully reviewed and selected from 64 submissions. They deal with fundamental issues in the specification, design, analysis, and implementation of programming languages and systems

Automated Deduction – CADE 28

This open access book constitutes the proceeding of the 28th International Conference on Automated Deduction, CADE 28, held virtually in July 2021. The 29 full papers and 7 system descriptions presented together with 2 invited papers were carefully reviewed and selected from 76 submissions. CADE is the major forum for the presentation of research in all aspects of automated deduction, including foundations, applications, implementations, and practical experience. The papers are organized in the following topics: Logical foundations; theory and principles; implementation and application; ATP and AI; and system descriptions

LIPIcs, Volume 261, ICALP 2023, Complete Volume

LIPIcs, Volume 261, ICALP 2023, Complete Volum