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A Variable Typed Logic of Effects
 Information and Computation
, 1993
"... In this paper we introduce a variable typed logic of effects inspired by the variable type systems of Feferman for purely functional languages. VTLoE (Variable Typed Logic of Effects) is introduced in two stages. The first stage is the firstorder theory of individuals built on assertions of equalit ..."
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Cited by 48 (12 self)
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In this paper we introduce a variable typed logic of effects inspired by the variable type systems of Feferman for purely functional languages. VTLoE (Variable Typed Logic of Effects) is introduced in two stages. The first stage is the firstorder theory of individuals built on assertions of equality (operational equivalence `a la Plotkin), and contextual assertions. The second stage extends the logic to include classes and class membership. The logic we present provides an expressive language for defining and studying properties of programs including program equivalences, in a uniform framework. The logic combines the features and benefits of equational calculi as well as program and specification logics. In addition to the usual firstorder formula constructions, we add contextual assertions. Contextual assertions generalize Hoare's triples in that they can be nested, used as assumptions, and their free variables may be quantified. They are similar in spirit to program modalities in ...
From Operational Semantics to Domain Theory
 Information and Computation
, 1995
"... This paper builds domain theoretic concepts upon an operational foundation. The basic operational theory consists of a single step reduction system from which an operational ordering and equivalence on programs are defined. The theory is then extended to include concepts from domain theory, includin ..."
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Cited by 36 (2 self)
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This paper builds domain theoretic concepts upon an operational foundation. The basic operational theory consists of a single step reduction system from which an operational ordering and equivalence on programs are defined. The theory is then extended to include concepts from domain theory, including the notions of directed set, least upper bound, complete partial order, monotonicity, continuity, finite element, !algebraicity, full abstraction, and least fixed point properties. We conclude by using these concepts to construct a (strongly) fully abstract continuous model for our language. In addition we generalize a result of Milner and prove the uniqueness of such models. Contents 1 Introduction 2 1.1 Related Work : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2 The Syntax and Semantics 3 2.1 Syntax : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 3 2.2 Semantics : : : : : : : : : : : : : : : : : : : : : : ...
From Operational to Denotational Semantics
 In MFPS 1991
, 1989
"... In this paper it is shown how operational semantic methods may be naturally extended to encompass many of the concepts of denotational semantics. This work builds on the standard development of an operational semantics as an interpreter and operational equivalence. The key addition is an operational ..."
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Cited by 18 (6 self)
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In this paper it is shown how operational semantic methods may be naturally extended to encompass many of the concepts of denotational semantics. This work builds on the standard development of an operational semantics as an interpreter and operational equivalence. The key addition is an operational ordering on sets of terms. From properties of this ordering a closure construction directly yields a fully abstract continuous cpo model. Furthermore, it is not necessary to construct the cpo, for principles such as soundness of fixedpoint induction may be obtained by direct reasoning from this new ordering. The end result is that traditional denotational techniques may be applied in a purely operational setting in a natural fashion, a matter of practical importance for developing semantics of realistic programming languages. 1 Introduction This paper aims to accomplish a degree of unification between operational and denotational approaches to programming language semantics by recasting d...
Reasoning about Functions with Effects
 See Gordon and Pitts
, 1997
"... ing and using (Lunif) we have that any two lambdas that are everywhere undefined are equivalent. The classic example of an everywhere undefined lambda is Bot 4 = x:app(x:app(x; x); x:app(x; x)) In f , another example of an everywhere undefined lambda is the "doforever" loop. Do 4 = f:Yv(Dox ..."
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Cited by 13 (1 self)
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ing and using (Lunif) we have that any two lambdas that are everywhere undefined are equivalent. The classic example of an everywhere undefined lambda is Bot 4 = x:app(x:app(x; x); x:app(x; x)) In f , another example of an everywhere undefined lambda is the "doforever" loop. Do 4 = f:Yv(Dox:Do(f(x)) By the recursive definition, for any lambda ' and value v Do(')(v) \Gamma!Ø Do(')('(v)) Reasoning about Functions with Effects 21 In f , either '(v) \Gamma!Ø v 0 for some v 0 or '(v) is undefined. In the latter case the computation is undefined since the redex is undefined. In the former case, the computation reduces to Do(')(v 0 ) and on we go. The argument for undefinedness of Bot relies only on the (app) rule and will be valid in any uniform semantics. In contrast the argument for undefinedness of Do(') relies on the (fred.isdef) property of f . Functional Streams We now illustrate the use of (Lunifsim) computation to reason about streams represented as functions ...
A First Order Logic of Effects
 Theoretical Computer Science
, 1996
"... In this paper we describe some of our progress towards an operational implementation of a modern programming logic. The logic is inspired by the variable type systems of Feferman, and is designed for reasoning about imperative functional programs. The logic goes well beyond traditional programming l ..."
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Cited by 4 (0 self)
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In this paper we describe some of our progress towards an operational implementation of a modern programming logic. The logic is inspired by the variable type systems of Feferman, and is designed for reasoning about imperative functional programs. The logic goes well beyond traditional programming logics, such as Hoare's logic and Dynamic logic in its expressibility, yet is less problematic to encode into higher order logics. The main focus of the paper is too present an axiomatization of the base first order theory. 1 Introduction VTLoE [34, 23, 35, 37, 24] is a logic for reasoning about imperative functional programs, inspired by the variable type systems of Feferman. These systems are two sorted theories of operations and classes initially developed for the formalization of constructive mathematics [12, 13] and later applied to the study of purely functional languages [14, 15]. VTLoE builds upon recent advances in the semantics of languages with effects [16, 19, 28, 32, 33] and go...
The Coverage of Operational Semantics
 Higher Order Operational Techniques in Semantics, Publications of the Newton Institute
, 1998
"... Techniques of operational semantics do not apply universally to all language varieties: techniques that work for simple functional languages may not apply to more realistic languages with features such as objects and memory effects. We focus mainly on the characterization of the socalled finite ele ..."
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Cited by 4 (0 self)
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Techniques of operational semantics do not apply universally to all language varieties: techniques that work for simple functional languages may not apply to more realistic languages with features such as objects and memory effects. We focus mainly on the characterization of the socalled finite elements. The presence of finite elements in a semantics allows for an additional powerful induction mechanism. We show that in some languages a reasonable notion of finite element may be defined, but for other languages this is problematic, and we analyse the reasons for these difficulties. We develop a formal theory of language embeddings and establish a number of properties of embeddings. More complex languages are given semantics by embedding them into simpler languages. Embeddings may be used to establish more general results and avoid reproving some results. It also gives us a formal metric to describe the gap between different languages. Dimensions of the untyped programming language design space addressed here include functions, injections, pairs, objects, and memories. 1
LCF Should Be Lifted
, 1988
"... : When observing termination of closed terms at all types in Plotkin's interpreter for PCF [11], the standard cpo model A V is not adequate. We define a new model, A Y , with lifted functional types and prove its adequacy for this notion of observation. We prove that with the addition of a parallel ..."
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Cited by 3 (1 self)
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: When observing termination of closed terms at all types in Plotkin's interpreter for PCF [11], the standard cpo model A V is not adequate. We define a new model, A Y , with lifted functional types and prove its adequacy for this notion of observation. We prove that with the addition of a parallel conditional and a convergence testing operator to the language, the model becomes fully abstract; with the addition of an existentiallike operator, the language becomes universal. Using the model as a guide, we develop a sound logic for the language. 1 Introduction The denotational semantics most appropriate for a programming language depends crucially upon the observations one makes about computations. In general, an observation is some important behavior of the interpreter [8]. For example, in the arithmetic, higherorder programming language PCF [11, 13], one usually chooses to observe the results of arithmetic expressionsthat a term of integer type reduces to a numeral. One may also...
Concurrency in the lambdacalculus: Higherorder Concurrent Constraint Programming (Extended Abstract)
, 1991
"... of Preliminary Report) December 4, 1991 Abstract We introduce higherorder versions of the determinate and nondeterminate concurrent constraint (cc) programming languages [Sar89]. Thereby, we propose a simple conceptual and semantic framework for the joint exploration of (concurrent) functional a ..."
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of Preliminary Report) December 4, 1991 Abstract We introduce higherorder versions of the determinate and nondeterminate concurrent constraint (cc) programming languages [Sar89]. Thereby, we propose a simple conceptual and semantic framework for the joint exploration of (concurrent) functional and (concurrent) (higherorder) (constraint) logic programming languages. 1 Introduction and overview The concurrent constraint (cc) programming paradigm is based on a set of very simple ideas, arising from concurrent logic programming and constraint logic programming. The basic references are [Sar89, SR90, SRP91, JSS91]; we summarize here briefly. Imperative languages may be thought of as based on the notion of storeasvaluation: a state of the computation is described by a valuation which assigns a unique value to each variable of interest. In constraintbased computation, this notion is replaced by that of storeasconstraintthe store is seen to contain pieces of partial information ...