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117
Types, Abstraction, and Parametric Polymorphism, Part 2
, 1991
"... The concept of relations over sets is generalized to relations over an arbitrary category, and used to investigate the abstraction (or logicalrelations) theorem, the identity extension lemma, and parametric polymorphism, for Cartesianclosedcategory models of the simply typed lambda calculus and P ..."
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Cited by 53 (1 self)
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The concept of relations over sets is generalized to relations over an arbitrary category, and used to investigate the abstraction (or logicalrelations) theorem, the identity extension lemma, and parametric polymorphism, for Cartesianclosedcategory models of the simply typed lambda calculus and PLcategory models of the polymorphic typed lambda calculus. Treatments of Kripke relations and of complete relations on domains are included.
Algorithmic Game Semantics
 In Schichtenberg and Steinbruggen [16
, 2001
"... Introduction SAMSON ABRAMSKY (samson@comlab.ox.ac.uk) Oxford University Computing Laboratory 1. Introduction Game Semantics has emerged as a powerful paradigm for giving semantics to a variety of programming languages and logical systems. It has been used to construct the first syntaxindependen ..."
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Cited by 47 (3 self)
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Introduction SAMSON ABRAMSKY (samson@comlab.ox.ac.uk) Oxford University Computing Laboratory 1. Introduction Game Semantics has emerged as a powerful paradigm for giving semantics to a variety of programming languages and logical systems. It has been used to construct the first syntaxindependent fully abstract models for a spectrum of programming languages ranging from purely functional languages to languages with nonfunctional features such as control operators and locallyscoped references [4, 21, 5, 19, 2, 22, 17, 11]. A substantial survey of the state of the art of Game Semantics circa 1997 was given in a previous Marktoberdorf volume [6]. Our aim in this tutorial presentation is to give a first indication of how Game Semantics can be developed in a new, algorithmic direction, with a view to applications in computerassisted verification and program analysis. Some promising steps have already been taken in this
Dynamic Opacity for Abstract Types
"... Existential types are the standard formalisation of abstract types. While this formulation is sufficient in entirely statically typed languages, it proves to be too weak for languages enriched with forms of dynamic typing: in the presence of operations performing type analysis, the abstraction barri ..."
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Cited by 44 (11 self)
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Existential types are the standard formalisation of abstract types. While this formulation is sufficient in entirely statically typed languages, it proves to be too weak for languages enriched with forms of dynamic typing: in the presence of operations performing type analysis, the abstraction barrier erected by the static typing rules for existential types is no longer impassable, because parametricity is violated. We present a lightweight calculus for polymorphic languages with abstract types that addresses this shortcoming. It features a variation of existential types that retains most of the simplicity of standard existentials. It relies on modified scoping rules and explicit coercions between the quantified variable and its witness type.
The Rewriting Logic Semantics Project
 SOS 2005 PRELIMINARY VERSION
, 2005
"... Rewriting logic is a flexible and expressive logical framework that unifies denotational semantics and SOS in a novel way, avoiding their respective limitations and allowing very succinct semantic definitions. The fact that a rewrite theory’s axioms include both equations and rewrite rules provides ..."
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Cited by 39 (11 self)
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Rewriting logic is a flexible and expressive logical framework that unifies denotational semantics and SOS in a novel way, avoiding their respective limitations and allowing very succinct semantic definitions. The fact that a rewrite theory’s axioms include both equations and rewrite rules provides a very useful “abstraction knob” to find the right balance between abstraction and observability in semantic definitions. Such semantic definitions are directly executable as interpreters in a rewriting logic language such as Maude, whose generic formal tools can be used to endow those interpreters with powerful program analysis capabilities.
A functional correspondence between monadic evaluators and abstract machines for languages with computational effects
 Theoretical Computer Science
, 2005
"... Abstract. We extend our correspondence between evaluators and abstract machines from the pure setting of the λcalculus to the impure setting of the computational λcalculus. We show how to derive new abstract machines from monadic evaluators for the computational λcalculus. Starting from (1) a gen ..."
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Cited by 38 (20 self)
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Abstract. We extend our correspondence between evaluators and abstract machines from the pure setting of the λcalculus to the impure setting of the computational λcalculus. We show how to derive new abstract machines from monadic evaluators for the computational λcalculus. Starting from (1) a generic evaluator parameterized by a monad and (2) a monad specifying a computational effect, we inline the components of the monad in the generic evaluator to obtain an evaluator written in a style that is specific to this computational effect. We then derive the corresponding abstract machine by closureconverting, CPStransforming, and defunctionalizing this specific evaluator. We illustrate the construction with the identity monad, obtaining yet again the CEK machine, and with a lifted state monad, obtaining a variant of the CEK machine with error and state. In addition, we characterize the tailrecursive stack inspection presented by Clements and Felleisen at ESOP 2003 as a lifted state monad. This enables us to combine the stackinspection monad with other monads and to construct abstract machines for languages with properly tailrecursive stack inspection and other computational effects. The construction scales to other monads—including one more properly dedicated to stack inspection than the lifted state monad—and other monadic evaluators. Keywords. Lambdacalculus, interpreters, abstract machines, closure conversion, transformation into continuationpassing style (CPS), defunctionalization, monads, effects, proper
The Requirement and Design Specification Language SPECTRUM  An Informal Introduction
, 1993
"... This paper gives a short introduction to the algebraic specification language Spectrum. Using simple, wellknown examples, the objectives and concepts of Spectrum are explained. The Spectrum language is based on axiomatic specification techniques and is oriented towards functional programs. Spectru ..."
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Cited by 36 (3 self)
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This paper gives a short introduction to the algebraic specification language Spectrum. Using simple, wellknown examples, the objectives and concepts of Spectrum are explained. The Spectrum language is based on axiomatic specification techniques and is oriented towards functional programs. Spectrum includes the following features: ffl partial functions, definedness logic and fixed point theory ffl higherorder elements and typed abstraction ffl nonstrict functions and infinite objects ffl full firstorder predicate logic with induction principles ffl predicative polymorphism with sort classes ffl parameterization and modularization Spectrum is based on the concept of loose semantics.
Rewriting Logic Semantics: From Language Specifications to Formal Analysis Tools
 In Proceedings of the IJCAR 2004. LNCS
, 2004
"... Abstract. Formal semantic definitions of concurrent languages, when specified in a wellsuited semantic framework and supported by generic and efficient formal tools, can be the basis of powerful software analysis tools. Such tools can be obtained for free from the semantic definitions; in our exper ..."
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Cited by 35 (9 self)
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Abstract. Formal semantic definitions of concurrent languages, when specified in a wellsuited semantic framework and supported by generic and efficient formal tools, can be the basis of powerful software analysis tools. Such tools can be obtained for free from the semantic definitions; in our experience in just the few weeks required to define a language’s semantics even for large languages like Java. By combining, yet distinguishing, both equations and rules, rewriting logic semantic definitions unify both the semantic equations of equational semantics (in their higherorder denotational version or their firstorder algebraic counterpart) and the semantic rules of SOS. Several limitations of both SOS and equational semantics are thus overcome within this unified framework. By using a highperformance implementation of rewriting logic such as Maude, a language’s formal specification can be automatically transformed into an efficient interpreter. Furthermore, by using Maude’s breadth first search command, we also obtain for free a semidecision procedure for finding failures of safety properties; and by using Maude’s LTL model checker, we obtain, also for free, a decision procedure for LTL properties of finitestate programs. These possibilities, and the competitive performance of the analysis tools thus obtained, are illustrated by means of a concurrent Camllike language; similar experience with Java (source and JVM) programs is also summarized. 1
Persistent HyperPrograms
 In Persistent Object Systems
, 1992
"... The traditional representation of a program as a linear sequence of text forces a particular style of program construction to ensure good programming practice. Tools such as syntax directed editors, compilers, linkers and file managers are required to translate and execute these linear sequences of ..."
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Cited by 34 (21 self)
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The traditional representation of a program as a linear sequence of text forces a particular style of program construction to ensure good programming practice. Tools such as syntax directed editors, compilers, linkers and file managers are required to translate and execute these linear sequences of text. At some stage in the execution sequence the source text is checked for type correctness and its translated form linked to values in the environment. When this is performed early in the execution process confidence in the correctness of the program is raised, at the cost of some flexibility of use. Persistent systems allow the persistent environment to participate in the program construction process. This raises the possibility of allowing the representations of source programs to include direct links to values that already exist in the environment. By analogy with hypertext, where a piece of text contains links to other pieces of text, this source representation is called a hyperprogram. This paper outlines how hyperprogramming facilities may be provided within a persistent system, discusses advantages of the technique and proposes some outstanding research areas. The advantages of hyperprogramming over conventional systems include the following: it allows more convenient program composition mechanisms; it allows earlier checking; it provides more flexible linking mechanisms; it allows more succinct program representations; and it allows procedure closures to be represented at a source code level.
Variables as resource in Hoare logics
 In 21st LICS
, 2006
"... Hoare logic is bedevilled by complex and unmemorable side conditions on the use of variables. We define a logic free of side conditions, and show that it admits translations of proofs in Hoare logic, thereby showing that nothing is lost. Our work draws on ideas from separation logic: program variabl ..."
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Cited by 33 (4 self)
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Hoare logic is bedevilled by complex and unmemorable side conditions on the use of variables. We define a logic free of side conditions, and show that it admits translations of proofs in Hoare logic, thereby showing that nothing is lost. Our work draws on ideas from separation logic: program variables are treated as resource and separated with ⋆, rather than as logical variables in disguise. For clarity we exclude a treatment of the heap. 1.
A General Framework for Hindley/Milner Type Systems with Constraints
, 2000
"... with constraints. The basic idea is to factor out the common core of previous extensions of the Hindley/Milner system. I present a Hindley/Milner system where the constraint part is a parameter. Speci c applications can be obtained by providing speci c constraint systems which capture the applicat ..."
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Cited by 30 (8 self)
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with constraints. The basic idea is to factor out the common core of previous extensions of the Hindley/Milner system. I present a Hindley/Milner system where the constraint part is a parameter. Speci c applications can be obtained by providing speci c constraint systems which capture the application in mind. For instance, the Hindley/Milner system can be recovered by instantiating the constraint part to the standard Herbrand constraint system. Type system instances of the general framework are sound if the underlying constraint system is sound. Furthermore, I give a generic type inference algorithm for the general framework, under sucient conditions on the speci c constraint system type inference yields principal types.