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Uniform proofs as a foundation for logic programming
 ANNALS OF PURE AND APPLIED LOGIC
, 1991
"... A prooftheoretic characterization of logical languages that form suitable bases for Prologlike programming languages is provided. This characterization is based on the principle that the declarative meaning of a logic program, provided by provability in a logical system, should coincide with its ..."
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Cited by 426 (124 self)
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A prooftheoretic characterization of logical languages that form suitable bases for Prologlike programming languages is provided. This characterization is based on the principle that the declarative meaning of a logic program, provided by provability in a logical system, should coincide with its operational meaning, provided by interpreting logical connectives as simple and fixed search instructions. The operational semantics is formalized by the identification of a class of cutfree sequent proofs called uniform proofs. A uniform proof is one that can be found by a goaldirected search that respects the interpretation of the logical connectives as search instructions. The concept of a uniform proof is used to define the notion of an abstract logic programming language, and it is shown that firstorder and higherorder Horn clauses with classical provability are examples of such a language. Horn clauses are then generalized to hereditary Harrop formulas and it is shown that firstorder and higherorder versions of this new class of formulas are also abstract logic programming languages if the inference rules are those of either intuitionistic or minimal logic. The programming language significance of the various generalizations to firstorder Horn clauses is briefly discussed.
A Logic Programming Approach To Manipulating Formulas And Programs
 IEEE Symp. Logic Programming
, 1994
"... : Firstorder Horn clause logic can be extended to a higherorder setting in which function and predicate symbols can be variables and terms are replaced with simply typed terms. For such a logic programming language to be complete in principle, it must incorporate higherorder unification. Althoug ..."
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Cited by 56 (17 self)
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: Firstorder Horn clause logic can be extended to a higherorder setting in which function and predicate symbols can be variables and terms are replaced with simply typed terms. For such a logic programming language to be complete in principle, it must incorporate higherorder unification. Although higherorder unification is more complex than usual firstorder unification, its availability makes writing certain kinds of programs far more straightforward. In this paper, we present such programs written in a higherorder version of Prolog called Prolog. These programs manipulate structures, such as formulas and programs, which contain abstractions or bound variables. We show how a simple natural deduction theorem prover can be implemented in this language. Similarly we demonstrate how several simple program transformers for a functional programming language can be written in Prolog. These Prolog programs exploit the availability of conversion and higherorder unification to elegantly ...
A ProofTheoretic Analysis of GoalDirected Provability
 Journal of Logic and Computation
, 1992
"... One of the distinguishing features of logic programming seems to be the notion of goaldirected provability, i.e. that the structure of the goal is used to determine the next step in the proof search process. It is known that by restricting the class of formulae it is possible to guarantee that a ..."
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Cited by 14 (7 self)
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One of the distinguishing features of logic programming seems to be the notion of goaldirected provability, i.e. that the structure of the goal is used to determine the next step in the proof search process. It is known that by restricting the class of formulae it is possible to guarantee that a certain class of proofs, known as uniform proofs, are complete with respect to provability in intuitionistic logic. In this paper we explore the relationship between uniform proofs and classes of formulae more deeply. Firstly we show that uniform proofs arise naturally as a normal form for proofs in firstorder intuitionistic sequent calculus. Next we show that the class of formulae known as hereditary Harrop formulae are intimately related to uniform proofs, and that we may extract such formulae from uniform proofs in two different ways. We also give results which may be interpreted as showing that hereditary Harrop formulae are the largest class of formulae for which uniform proo...
Anaphorie reference to events and actions: a representation and its advantages
 In Proc. COLING'88
, 1988
"... Tiffs paper focuses on anaphora interpreted as referring t'o entities of type event and action. It considers two issues: (i) what aspects of the discourse give evidence of the events and the actions the speaker is talking about, and (ii) how actions and events are represented in the discourse i ..."
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Cited by 1 (0 self)
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Tiffs paper focuses on anaphora interpreted as referring t'o entities of type event and action. It considers two issues: (i) what aspects of the discourse give evidence of the events and the actions the speaker is talking about, and (ii) how actions and events are represented in the discourse in order to be able to refer to them anaphorically. 1