scholarly journals Semantics, Modularity, and Rewriting Logic

1998 ◽  
Vol 5 (42) ◽  
Author(s):  
Peter D. Mosses
Keyword(s):  
Operational Semantics ◽  
Denotational Semantics ◽  
Rewriting Logic ◽  
Semantic Description ◽  
Semantic Framework ◽  
Action Semantics ◽  
Strong Indicator ◽  
Hybrid Framework ◽  
Structural Operational Semantics ◽  
Modular Monadic Semantics

A complete formal semantic description of a practical programming language (such as Java) is likely to be a lengthy document, regardless of which semantic framework is being used. Good modularity of the description is important to the person(s) developing it, to facilitate reuse, change, and extension. Unfortunately, the conventional versions<br />of the major semantic frameworks have rather poor modularity.<br /> In this paper, we first recall some approaches that improve the modularity of denotational semantics, namely action semantics, modular monadic semantics, and a hybrid framework that combines these: modular monadic action semantics. We then address the issue of modularity in operational semantics, which appears to have received comparatively little attention so far, and report on some preliminary investigations of how one might achieve the same kind of modularity in structural operational semantics as the use of monad transformers<br />can provide in denotational semantics|this is the main technical contribution of the paper. Finally, we briefly consider the representation of structural operational semantics in rewriting logic, and speculate on the possibility of using it to interpret programs in the described language. Providing powerful meta-tools for such semantics-based interpretation<br />is an interesting potential application of rewriting logic;<br />good modularity of the semantic descriptions may be crucial for the practicality of using the tools.<br />Much of the paper consists of (very) simple examples of semantic descriptions in the various frameworks, illustrating the degree of reformulation needed when extending the described language|a strong indicator of modularity. Throughout, it is assumed that the reader has some familiarity with the concepts and notation of denotational and structural operational semantics. Familiarity with the basic notions of monads and monad transformers is not a prerequisite.

scholarly journals On the Action Semantics of Concurrent Programming Languages

1992 ◽  
Vol 21 (424) ◽  
Author(s):  
Peter D. Mosses
Keyword(s):  
Programming Languages ◽  
Operational Semantics ◽  
Denotational Semantics ◽  
Semantic Description ◽  
Paper Briefly ◽  
Action Semantics ◽  
Concurrent Programming Languages ◽  
Structural Operational Semantics ◽  
Bisimulation Equivalence ◽  
Basic Concepts

<p>Action semantics is a framework for semantic description of prograrnming languages. In this framework, actions are semantic entities, used to represent the potential behaviour of programs --- also the contributions that parts of programs make to such behaviour. The notation for expressing actions, called action notation, is combinator-based. It is used in much the same way that lambda-notation is used in denotational semantics. However, the essence of action notation is operational, rather than mathematical, and its meaning is formally defined by a structural operational semantics together with a bisimulation equivalence.</p><p>This paper briefly motivates action semantics, and explains the basic concepts. It then illustrates the use of the framework by giving an action semantic description of a small example language. This language includes a simple form of concurrency: tasks that may synchronize by means of rendezvous. The paper also discusses the operational semantics of action notation, focusing on the primitive actions that represent asynchronous message transmission and process initiation.</p>

scholarly journals On the foundations of final coalgebra semantics: non-well-founded sets, partial orders, metric spaces

1998 ◽  
Vol 8 (5) ◽  
pp. 481-540 ◽  
Author(s):  
DANIELE TURI ◽  
JAN RUTTEN
Keyword(s):  
Computer Science ◽  
Mathematical Theory ◽  
Metric Spaces ◽  
Operational Semantics ◽  
Denotational Semantics ◽  
Partial Orders ◽  
Present Survey ◽  
Induction Principle ◽  
Structural Operational Semantics ◽  
Modern Mathematics

This paper, a revised version of Rutten and Turi (1993), is part of a programme aiming at formulating a mathematical theory of structural operational semantics to complement the established theory of domains and denotational semantics to form a coherent whole (Turi 1996; Turi and Plotkin 1997). The programme is based on a suitable interplay between the induction principle, which pervades modern mathematics, and a dual, non-standard ‘coinduction principle’, which underlies many of the recursive phenomena occurring in computer science.The aim of the present survey is to show that the elementary categorical notion of a final coalgebra is a suitable foundation for such a coinduction principle. The properties of coalgebraic coinduction are studied both at an abstract categorical level and in some specific categories used in semantics, namely categories of non-well-founded sets, partial orders and metric spaces.

scholarly journals A Modular SOS for Action Notation

1999 ◽  
Vol 6 (56) ◽  
Author(s):  
Peter D. Mosses
Keyword(s):  
Programming Languages ◽  
Operational Semantics ◽  
Denotational Semantics ◽  
Specification Language ◽  
Algebraic Specification ◽  
Recent Proposal ◽  
Structural Operational Semantics ◽  
The Common ◽  
Basic Concepts ◽  
Pragmatic Aspect

Modularity is an important pragmatic aspect of semantic<br />descriptions: good modularity is needed to allow the reuse of existing descriptions when extending or changing the described language. In denotational semantics, the issue of modularity has received much attention, and appropriate abstractions have been introduced, so that definitions of semantic functions may be independent of the details of how computations are modeled. In structural operational semantics (SOS), however, this issue has largely been neglected, and SOS descriptions of programming languages typically exhibit rather poor modularity; the original SOS given for Action Notation (the notation for the semantic entities used in action semantics) suffered from the same problem.<br />This paper recalls a recent proposal, called MSOS, for obtaining a high<br />degree of modularity in SOS, and presents an MSOS description of Action<br />Notation. Due to its modularity, the MSOS description pinpoints some<br />complications in the design of Action Notation, and should facilitate the<br />design of an improved version of the notation. It also provides a major<br />example of the applicability of the MSOS framework.<br />The reader is assumed to be familiar with conventional SOS and with<br />the basic concepts and constructs of Action Notation. The description<br />of Action Notation is formulated almost entirely in Casl, the common<br />algebraic specification language.

scholarly journals The Operational Semantics of Action Notation

1992 ◽  
Vol 21 (418) ◽  
Author(s):  
Peter D. Mosses
Keyword(s):  
Operational Semantics ◽  
Action Semantics ◽  
Structural Operational Semantics ◽  
Algebraic Laws

Action notation is used in the action semantics fratnework, for specifying actions representing program behaviour. It is defined by a structural operational semantics together with a bisimulation-based equivalence that satisfies some simple algebraic laws.

scholarly journals A Semantic Framework for Program Debugging

10.29007/q2h6 ◽  
2018 ◽  
Author(s):  
Wei Li
Keyword(s):  
Operational Semantics ◽  
Test Case ◽  
Main Task ◽  
Semantic Framework ◽  
Program Debugging ◽  
Design Error ◽  
Automated Debugging ◽  
Different Types ◽  
Structural Operational Semantics ◽  
Logical Design

This work aims to build a semantic framework for automated debugging. A debugging process consists of tracing, locating, and fixing processes consecutively. The first two processes are accomplished by a tracing procedure and a locating procedure, respectively. The tracing procedure reproduces the execution of a failed test case with well-designed data structures and saves necessary information for locating bugs. The locating procedure will use the information obtained from the tracing procedure to locate ill-designed statements and to generate a fix-equation, the solution of which is a function that will be used to fix the bugs. A structural operational semantics is given to define the functions of the tracing and locating procedure. Both procedures are proved to terminate and produces one fix-equation. The main task of fixing process is to solve the fix-equation. It turns out that for a given failed test case, there exist three different types of solutions: 1. the bug is solvable, there exists a solution of the fix-equation, and the program can be repaired. 2. There exists a non-linear error in the program, the fix-equation generated at each round of the locating procedure is solvable, but a new bug will arise when the old bug is being fixed. 3. There exists a logical design error and the fix-equation is not solvable.

scholarly journals Persistent Stochastic Non-Interference

2021 ◽  
Vol 181 (1) ◽  
pp. 1-35
Author(s):  
Jane Hillston ◽  
Andrea Marin ◽  
Carla Piazza ◽  
Sabina Rossi
Keyword(s):  
Process Algebra ◽  
Operational Semantics ◽  
Evaluation Process ◽  
Decision Algorithm ◽  
Secure Systems ◽  
Information Flow Security ◽  
Structural Operational Semantics ◽  
Timing Properties ◽  
Functional Point ◽  
Security Property

In this paper, we study an information flow security property for systems specified as terms of a quantitative Markovian process algebra, namely the Performance Evaluation Process Algebra (PEPA). We propose a quantitative extension of the Non-Interference property used to secure systems from the functional point view by assuming that the observers are able to measure also the timing properties of the system, e.g., the response time of certain actions or its throughput. We introduce the notion of Persistent Stochastic Non-Interference (PSNI) based on the idea that every state reachable by a process satisfies a basic Stochastic Non-Interference (SNI) property. The structural operational semantics of PEPA allows us to give two characterizations of PSNI: one based on a bisimulation-like equivalence relation inducing a lumping on the underlying Markov chain, and another one based on unwinding conditions which demand properties of individual actions. These two different characterizations naturally lead to efficient methods for the verification and construction of secure systems. A decision algorithm for PSNI is presented and an application of PSNI to a queueing system is discussed.

scholarly journals A structured alternative to Prolog with simple compositional semantics

2011 ◽  
Vol 11 (4-5) ◽  
pp. 611-627
Author(s):  
ANTÓNIO PORTO
Keyword(s):  
Denotational Semantics ◽  
Expressive Power ◽  
Compositional Semantics ◽  
Variable Binding ◽  
Semantic Framework ◽  
Local Case ◽  
Real World Applications ◽  
Full Power ◽  
Definition Of ◽  
Concrete Language

AbstractProlog's very useful expressive power is not captured by traditional logic programming semantics, due mainly to the cut and goal and clause order. Several alternative semantics have been put forward, exposing operational details of the computation state. We propose instead to redesign Prolog around structured alternatives to the cut and clauses, keeping the expressive power and computation model but with a compositional denotational semantics over much simpler states—just variable bindings. This considerably eases reasoning about programs, by programmers and tools such as a partial evaluator, with safe unfolding of calls through predicate definitions. Anif-then-elseacross clauses replaces most uses of the cut, but the cut's full power is achieved by anuntilconstruct. Disjunction, conjunction anduntil, along with unification, are the primitive goal types with a compositional semantics yielding sequences of variable-binding solutions. This extends to programs via the usual technique of a least fixpoint construction. A simple interpreter for Prolog in the alternative language, and a definition ofuntilin Prolog, establish the identical expressive power of the two languages. Many useful control constructs are derivable from the primitives, and the semantic framework illuminates the discussion of alternative ones. The formalisation rests on a term language with variable abstraction as in the λ-calculus. A clause is an abstraction on the call arguments, a continuation, and the local variables. It can be inclusive or exclusive, expressing a local case bound to a continuation by either a disjunction or anif-then-else. Clauses are open definitions, composed (and closed) with simple functional application β-reduction). This paves the way for a simple account of flexible module composition mechanisms.Cube, a concrete language with the exposed principles, has been implemented on top of a Prolog engine and successfully used to build large real-world applications.

scholarly journals A Presheaf Semantics of Value-Passing Processes

1996 ◽  
Vol 3 (44) ◽  
Author(s):  
Glynn Winskel
Keyword(s):  
Operational Semantics ◽  
Denotational Semantics ◽  
Domain Theory ◽  
Process Calculi ◽  
Traditional Definition ◽  
Open Maps

This paper investigates presheaf models for process calculi with<br />value passing. Denotational semantics in presheaf models are shown<br />to correspond to operational semantics in that bisimulation obtained<br />from open maps is proved to coincide with bisimulation as defined<br />traditionally from the operational semantics. Both "early" and "late"<br />semantics are considered, though the more interesting "late" semantics<br />is emphasised. A presheaf model and denotational semantics is proposed<br />for a language allowing process passing, though there remains<br />the problem of relating the notion of bisimulation obtained from open<br />maps to a more traditional definition from the operational semantics.<br />A tentative beginning is made of a "domain theory" supporting<br />presheaf models.

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