Results 1  10
of
18
Higherorder logic programming
 HANDBOOK OF LOGIC IN AI AND LOGIC PROGRAMMING, VOLUME 5: LOGIC PROGRAMMING. OXFORD (1998
"... ..."
A FineGrained Notation for Lambda Terms and Its Use in Intensional Operations
 Journal of Functional and Logic Programming
, 1996
"... We discuss issues relevant to the practical use of a previously proposed notation for lambda terms in contexts where the intensions of such terms have to be manipulated. This notation uses the `nameless' scheme of de Bruijn, includes expressions for encoding terms together with substitutions to ..."
Abstract

Cited by 25 (9 self)
 Add to MetaCart
We discuss issues relevant to the practical use of a previously proposed notation for lambda terms in contexts where the intensions of such terms have to be manipulated. This notation uses the `nameless' scheme of de Bruijn, includes expressions for encoding terms together with substitutions to be performed on them and contains a mechanism for combining such substitutions so that they can be effected in a common structure traversal. The combination mechanism is a general one and consequently difficult to implement. We propose a simplification to it that retains its functionality in situations that occur commonly in fireduction. We then describe a system for annotating terms to determine if they can be affected by substitutions generated by external ficontractions. These annotations can lead to a conservation of space and time in implementations of reduction by permitting substitutions to be performed trivially in certain situations. The use of the resulting notation in the reduction...
Scoping Constructs In Logic Programming: Implementation Problems And Their Solution
, 1995
"... Machine (WAM). The provision of implications in goals results in the possibility of program clauses being added to the program for the purpose of solving specific subgoals. A naive scheme based on asserting and retracting program clauses does not suffice for implementing such additions for two reaso ..."
Abstract

Cited by 21 (9 self)
 Add to MetaCart
Machine (WAM). The provision of implications in goals results in the possibility of program clauses being added to the program for the purpose of solving specific subgoals. A naive scheme based on asserting and retracting program clauses does not suffice for implementing such additions for two reasons. First, it is necessary to also support the resurrection of an earlier existing program in the face of backtracking. Second, the possibility for implication goals to be surrounded by quantifiers requires a consideration of the parameterization of program clauses by bindings for their free variables. Devices for supporting these additional requirements are described as also is the integration of these devices into the WAM. Further extensions to the machine are outlined for handling higherorder additions to the language. The ideas Work on this paper has been partially supported by NSF Grants CCR8905825 and CCR 9208465. Address correspondence to Gopalan Nadathur, Department of Compute...
Implementation Considerations for HigherOrder Features in Logic Programming
, 1993
"... This paper examines implementation problems that arise from providing for aspects of higherorder programming within and enhancing the metalanguage abilities of logic programming. One issue of concern is a representation for the simplytyped lambda terms that replace the usual firstorder terms as ..."
Abstract

Cited by 14 (10 self)
 Add to MetaCart
This paper examines implementation problems that arise from providing for aspects of higherorder programming within and enhancing the metalanguage abilities of logic programming. One issue of concern is a representation for the simplytyped lambda terms that replace the usual firstorder terms as data structures; this representation must support an efficient realization of ...conversion operations on these terms. Another issue is the handling of higherorder unification that becomes an integral part of the computational model. An implementation must cater to the branching nature of this operation and also provide a means for temporarily suspending the solution of a unification problem. A final issue concerns the treatment of goals whose structure is not statically apparent. These problems are discussed in detail and solutions to them are described. A representation for lambda terms is presented that uses the de Bruijn "nameless" notation and also permits reduction substitutions to be performed lazily. This notation obviates ...conversion and also supports an efficient implementation of ...reduction. Branching in unification is implemented by using a depthfirst search strategy with backtracking. A structure that is called a branch point record and is akin to the choice point record of the Warren Abstract Machine (WAM) is described for remembering alternatives in unification. An explicit representation for unification problems is presented that permits sharing and also supports the rapid reinstatement of earlier versions of the problem. The implementation of unification is tuned to yield an efficient solution to firstorder like problems, in fact through the use of compiled code as in the WAM. A compilation method is also discussed for goals whose structure changes during execution. Th...
A Notation for Lambda Terms II: Refinements and Applications
, 1994
"... Issues that are relevant to the representation of lambda terms in contexts where their intensions have to be manipulated are examined. The basis for such a representation is provided by the suspension notation for lambda terms that is described in a companion paper. This notation obviates ffconver ..."
Abstract

Cited by 12 (2 self)
 Add to MetaCart
Issues that are relevant to the representation of lambda terms in contexts where their intensions have to be manipulated are examined. The basis for such a representation is provided by the suspension notation for lambda terms that is described in a companion paper. This notation obviates ffconversion in the comparison of terms by using the `nameless' scheme of de Bruijn and also permits a delaying of substitutions by including a class of terms that encode other terms together with substitutions to be performed on them. The suspension notation contains a mechanism for `merging' substitutions so that they can be effected in a common structure traversal. The mechanism is cumbersome to implement in its full generality and a simplification to it is considered. In particular, the old merging operations are eliminated in favor of new ones that capture some of their functionality and that permit a simplified syntax for terms. The resulting notation is refined by the addition of annotations ...
Optimizing HigherOrder Pattern Unification
 19th International Conference on Automated Deduction
, 2003
"... We present an abstract view of existential variables in a dependently typed lambdacalculus based on modal type theory. This allows us to justify optimizations to pattern unification such as linearization, which eliminates many unnecessary occurschecks. The presented modal framework explains a ..."
Abstract

Cited by 12 (7 self)
 Add to MetaCart
We present an abstract view of existential variables in a dependently typed lambdacalculus based on modal type theory. This allows us to justify optimizations to pattern unification such as linearization, which eliminates many unnecessary occurschecks. The presented modal framework explains a number of features of the current implementation of higherorder unification in Twelf and provides insight into several optimizations. Experimental results demonstrate significant performance improvement in many example applications of Twelf, including those in the area of proofcarrying code.
Choices in representation and reduction strategies for lambda terms in intensional contexts
 J. Autom. Reasoning
, 2004
"... ..."
Collection analysis for Horn clause programs
 In Proceedings of PPDP 2006: 8th International ACM SIGPLAN Conference on Principles and Practice of Declarative Programming
, 2006
"... dale.miller [at] inria.fr ..."
The Architecture of an Implementation of λProlog: Prolog/Mali
, 1992
"... λProlog is a logic programming language accepting a more general clause form than standard Prolog (namely hereditary Harrop formulas instead of Horn formulas) and using simply typed λterms as a term domain instead of first order terms. Despite these extensions, it is still amenable to goaldirected ..."
Abstract

Cited by 2 (0 self)
 Add to MetaCart
λProlog is a logic programming language accepting a more general clause form than standard Prolog (namely hereditary Harrop formulas instead of Horn formulas) and using simply typed λterms as a term domain instead of first order terms. Despite these extensions, it is still amenable to goaldirected proofs and can still be given procedural semantics. However, the execution of λProlog programs requires several departures from the standard resolution scheme. First, the augmented clause form causes the program (a set of clauses) and the signature (a set of constants) to be changeable, but in a very disciplined way. Second, the new term domain has a semidecidable and infinitary unification theory, and it introduces the need for a fireduction operation at runtime. MALI is an abstract memory that is suitable for storing the searchstate of depthfirst search processes. Its main feature is its efficient memory management. We have used an original PrologtoC translation: predicates are trans...
Imagining CLP(. . .
, 1994
"... We study under which conditions the domain of terms () and the equality theory of the calculus (j fffi ) form the basis of a usable constraint logic programming language (CLP). The conditions are that the equality theory must contain axiom j, and the formula language must depart from Horn clauses ..."
Abstract

Cited by 1 (1 self)
 Add to MetaCart
We study under which conditions the domain of terms () and the equality theory of the calculus (j fffi ) form the basis of a usable constraint logic programming language (CLP). The conditions are that the equality theory must contain axiom j, and the formula language must depart from Horn clauses and accept universal quantifications and implications in goals. In short, CLP(, j fffi ) must be close to Prolog.