Showing papers on "Operational semantics published in 1974"

On the Relation between Direct and Continuation Semantics

Abstract: The use of continuations in the definition of programming languages has gained considerable currency recently, particularly in conjunction with the lattice-theoretic methods of D. Scott. Although continuations are apparently needed to provide a mathematical semantics for non-applicative control features, they are unnecessary for the definition of a purely applicative language, even when call-by-value occurs. This raises the question of the relationship between the direct and the continuation semantic functions for a purely applicative language. We give two theorems which specify this relationship and show that, in a precise sense, direct semantics are included in continuation semantics.

Initial algebra semantics

Abstract: Many apparently divergent approaches to specifying formal semantics for programming languages are applications of initial algebra semantics. Here we provide an overview of the concept of initial algebra semantics.

On the interpretation of recursive program schemes

Abstract: This paper extends a previous paper [8] where we described a semantics for monadic recursive program schemes (also called Scott-de Bakker schemes) The method consists in considering program schemes as rewriting systems which generate subsets of a free magma and defining a mapping of such subsets in a proper domain of functions In our previous paper, dealing with a simple case, the combinatorial properties on which the whole construction relies were well known or at least immediate corollaries of wellknown results in the theory of context-free languages In the present case, the rewriting systems which we are led to consider, and which in a very naturalway could be called algebraic rewriting systems or grammars on a free magma, have been little considered in the literature and we need establish first a number of results concerning such systems This is done in a first part of this paper Afterwards we establish the link between such rewriting systems and recursive program schemes, define the function computed by such a scheme under a given discrete interpretation and apply the results of part I to show the equivalence of one definition of this function with the classical definitions : the operational semantics as described for example in [3], Kleene's definition of recursive function [2], the fix-point semantics as it can be found in [5], [6] or [10]

Semantics and axiomatics of a simple recursive language.

Abstract: In this paper, we provide a simple recursive programming language with a semantics and a formal proof system, along the lines of [5], [17] and [23]. We show that the semantics used is the “best” possible if one admits the validity of Algol's copy rule, and that the proof system is complete with respect to the semantics. The definitions and methods used are meant to provide a basis for a broader theory of program schemas, which models parallel as well as sequential programs.

Proving Programs by Sets of Computations

Abstract: By a computation of a program we mean any finite or infinite sequence of consecutive data-vector states generated by the program during a run. The set of all such computations can be considered as the program meaning. Analysing programs by sets of computations permits one to deal not only with input-output properties like correctness or termination, but also with properties of runs independently are they finite or not. In particular one can analyse system-like programs, where no output at all is expected. Given a program to be analysed we split it into a finite number of modules each of them simple enough for the set of all its computations to be obvioust. Sets of computations associated to modules are combined then into a global set in a way that is described by operational semantics. This semantics — being of litle use for program analysis — is supplemented then by a fixed point semantics that is proved equivalent to the former. Two examples of program analysis are considered: the McCarthy's 91-procedure and a consumer-producer system-like program.

Computability on Continuous Higher Types and its Role in the Semantics of Programming Languages

Abstract: This paper is about mathematical problems in programming language semantics and their influence on recursive function theory. In the process if constructing computable Scott models of the lambda calculus we examine the concepts of deterministic and non-deterministic effective operators of all finite types and continuous deterministic and non-deterministic partial computable operators on continuous inputs of all finite types. These are new recursion theoretic concepts which are appropriate to semantics and were inspired in part by Scott''s work on continuity.

Visible semantics for programming languages

Abstract: Operational models for the semantics of programming languages often employ data structure diagrams for representing computation states (snapshots). Provided that these data structures are simple enough, automation of their display is feasible, supplying "visible semantics" for the languages modelled.One automation technique is described for displaying ALGOL program snapshots, based on the Contour Model, and the structure of the implemented display processor is discussed. Extensions and generalizations of this processor for use with a wide variety of programming languages are suggested.

Relations between Semantics and Complexity of Recursive Programs

Abstract: Inside theoretical computer science, there has often been a trend to build specific theories (both at an abstract and at a concrete level) to deal with specific aspects of automatic computing, like program structure, semantics, computational complexity. On the other side,more recently, there has been a growing need for relating results concerning the various aspects of automatic computing in order to enrich the different approaches and in order to build more adequate theories.