Results 1  10
of
19
The Barendregt Cube with Definitions and Generalised Reduction
, 1997
"... In this paper, we propose to extend the Barendregt Cube by generalising reduction and by adding definition mechanisms. We show that this extension satisfies all the original properties of the Cube including Church Rosser, Subject Reduction and Strong Normalisation. Keywords: Generalised Reduction, ..."
Abstract

Cited by 42 (20 self)
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In this paper, we propose to extend the Barendregt Cube by generalising reduction and by adding definition mechanisms. We show that this extension satisfies all the original properties of the Cube including Church Rosser, Subject Reduction and Strong Normalisation. Keywords: Generalised Reduction, Definitions, Barendregt Cube, Church Rosser, Subject Reduction, Strong Normalisation. Contents 1 Introduction 3 1.1 Why generalised reduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.2 Why definition mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 The item notation for definitions and generalised reduction . . . . . . . . . . 4 2 The item notation 7 3 The ordinary typing relation and its properties 10 3.1 The typing relation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 Properties of the ordinary typing relation . . . . . . . . . . . . . . . . . . . . 13 4 Generalising reduction in the Cube 15 4.1 The generalised...
A unified approach to Type Theory through a refined λcalculus
, 1994
"... In the area of foundations of mathematics and computer science, three related topics dominate. These are calculus, type theory and logic. ..."
Abstract

Cited by 14 (13 self)
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In the area of foundations of mathematics and computer science, three related topics dominate. These are calculus, type theory and logic.
and
, 1996
"... We are grateful for the discussions with Roel Bloo, Tijn Borghuis, Erik Poll and Phil Wadler and for the helpful remarks received from them. In particular, we are grateful to Phil Wadler who has recommended that we dispose of 's and 's as in (x)( y)y and write (x)[y]y instead. We are also ..."
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We are grateful for the discussions with Roel Bloo, Tijn Borghuis, Erik Poll and Phil Wadler and for the helpful remarks received from them. In particular, we are grateful to Phil Wadler who has recommended that we dispose of 's and 's as in (x)( y)y and write (x)[y]y instead. We are also grateful to Peter Peters for his help concerning Latex and email which enabled us to keep exchanging drafts and corrections of the present paper. Last but not least, we are grateful to the anonymous referees for their useful comments. y
Beyond betaReduction in Church's ...
, 1996
"... In this paper, we shall write ! using a notation, item notation, which enables one to make more redexes visible, and shall extend fireduction to all visible redexes. We will prove that ! written in item notation and accommodated with extended reduction, satisfies all its original properties (such a ..."
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In this paper, we shall write ! using a notation, item notation, which enables one to make more redexes visible, and shall extend fireduction to all visible redexes. We will prove that ! written in item notation and accommodated with extended reduction, satisfies all its original properties (such as Church Rosser, Subject Reduction and Strong Normalisation). The notation itself is very simple: if I translates classical terms to our notation, then I(t 1 t 2 ) j (I(t 2 )ffi)I(t 1 ) and I( v:ae :t) j (ae v )I(t). For example, t j (( x7 :X4 :( x6 :X3 : x5 :X1!X2 :x 5 x 4 )x 3 )x 2 )x 1 , can be written in our item notation as I(t) j (x 1 ffi)(x 2 ffi)(X 4 x7 )(x 3 ffi)(X 3 x6 )((X 1 ! X 2 ) x5 )(x 4 ffi)x 5 where the visible redexes are based on all the matching fficouples. So here, the redexes are based on (x 2 ffi)(X 4 x7 ), (x 3 ffi)(X 3 x6 ) and (x 1 ffi)((X 1 ! X 2 ) x5 ). In classical notation however, only the redexes based on ( x7 :X4 : \Gamma \Gamma)x 2 and ( x6 :X3 : \Gamm...
The LambdaCube With Classes Which Approximate Reductional Equivalence
, 1995
"... We study lambda calculus and refine the notions of fireduction and fiequality. In particular, we define the operation TS (term reshuffling) on terms which reshuffles a term in such a way that more redexes become visible. Two terms are called shuffleequivalent if they have syntactically equivalent ..."
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We study lambda calculus and refine the notions of fireduction and fiequality. In particular, we define the operation TS (term reshuffling) on terms which reshuffles a term in such a way that more redexes become visible. Two terms are called shuffleequivalent if they have syntactically equivalent TSimages. The shuffleequivalence classes are shown to divide the classes of fiequal terms into smaller classes consisting of terms with similar reduction behaviour. The refinement of fireduction from a relation on terms to a relation on shuffle classes, called shufflereduction, allows one to make more redexes visible and to contract these newly visible redexes. This enables one to have more freedom in choosing the reduction path of a term, which can result in smaller terms along the reduction path if a clever reduction strategy is used. Moreover, this gain in reductional breadth is not at the expense of reductional length. We show that the cube of [Barendregt 92] extended with shuffle...
Refining Reduction in the lambda calculus
, 1996
"... We introduce a calculus notation which enables us to detect in a term, more fi redexes than in the usual notation. On this basis, we define an extended fireduction which is yet a subrelation of conversion. The Church Rosser property holds for this extended reduction. Moreover, we show that we c ..."
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We introduce a calculus notation which enables us to detect in a term, more fi redexes than in the usual notation. On this basis, we define an extended fireduction which is yet a subrelation of conversion. The Church Rosser property holds for this extended reduction. Moreover, we show that we can transform generalised redexes into usual ones by a process called "term reshuffling". Keywords: Item notation, Redexes, Church Rosser. Contents 1 Introduction 3 1.1 The item notation and visible redexes . . . . . . . . . . . . . . . . . . . . . . 4 1.2 The system . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Generalising redexes and fireduction 7 2.1 Extending redexes from segments to couples . . . . . . . . . . . . . . . . . . . 7 2.2 Extending fireduction and the Church Rosser theorem . . . . . . . . . . . . . 8 3 Term reshuffling 10 3.1 Partitioning terms into bachelor and wellbalanced segments . . . . . . . . . . 11 3.2 The reshuffling procedure...
Term Reshuffling in the Barendregt Cube
"... This paper will concentrate on a new feature related to reshuffling terms so that more redexes become visible. The idea is explained as follows: Assume a redex is a `[' next to a `]'. What will happen in a term of the form `[ [ ] [ ] ]' ? We know that the two internal `[ ]' are ..."
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This paper will concentrate on a new feature related to reshuffling terms so that more redexes become visible. The idea is explained as follows: Assume a redex is a `[' next to a `]'. What will happen in a term of the form `[ [ ] [ ] ]' ? We know that the two internal `[ ]' are redexes, but classical notation does not allow us to say that the outside `[' and `]' form a redex. In [BKN 9x], we generalised the notion of a redex from a pair of adjacent matching parentheses to simply a pair of matching parentheses. Hence, with generalised reduction all the three redexes are visible in `[ [ ] [ ] ]'. In this paper, we propose to reshuffle `[ [ ] [ ] ]' to `[ ] [ ] [ ]' where the first `[' has been moved next to the last `]'. The item notation enables us to see the matching parentheses and to reshuffle terms so that all matching paretheses become adjacent
and
, 1996
"... We are grateful for the discussions with Roel Bloo, Tijn Borghuis, Erik Poll and Phil Wadler and for the helpful remarks received from them. In particular, we are grateful to Phil Wadler who has recommended that we dispose of 's and 's as in (x)( y)y and write (x)[y]y instead. We are also ..."
Abstract
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We are grateful for the discussions with Roel Bloo, Tijn Borghuis, Erik Poll and Phil Wadler and for the helpful remarks received from them. In particular, we are grateful to Phil Wadler who has recommended that we dispose of 's and 's as in (x)( y)y and write (x)[y]y instead. We are also grateful to Peter Peters for his help concerning Latex and email which enabled us to keep exchanging drafts and corrections of the present paper. Last but not least, we are grateful to the anonymous referees for their useful comments. y
and
, 1996
"... In the area of foundations of mathematics and computer science, three related topics dominate. These are calculus, type theory and logic. There are moreover, many versions of calculi and type theories. In these versions, the presence of logic ranges from the nonexistant to the dominant. In fact, ..."
Abstract
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In the area of foundations of mathematics and computer science, three related topics dominate. These are calculus, type theory and logic. There are moreover, many versions of calculi and type theories. In these versions, the presence of logic ranges from the nonexistant to the dominant. In fact, the three subjects of calculus, logic and type theory, got separated due to the appearence of the paradoxes. Moreover, the existence of various versions of each topic is due to the need to get back to the lost paradise which allowed a great freedom in mixing expressivity and logic. In any case, the presence of such a variety of systems calls for a framework to unify them all. Barendregt's cube for example, is an attempt to unify various type systems and his associated logic cube is an attempt to nd connections between type theories and logic. We devise a new notation which enables categorising most of the known systems in a unied way. More precisely, we sketch the general structure of a system of typed lambda calculus and show that this system has enough expressive power for the description of various existing systems, ranging from Automathlike systems to singlytyped Pure Type Systems. The system We are grateful for Erik Poll who has read the paper carefully and for his productive comments. We are also grateful for discussions with Henk Barendregt, Inge Bethke, Tijn Borghuis and for the helpful remarks received from them. Furthermore, we are indebted to the anonymous referee for his/her useful suggestions and remarks. y