4,983 research outputs found
Suggestions for a non-monotonic feature logic
We use Scott's domain theory and methods from Reiter's default logic to suggest some ways of modelling default constraints in feature logic. We show how default feature rules, derived from default constraints, can be used to give ways to augment strict feature structures with default information
Cirquent calculus deepened
Cirquent calculus is a new proof-theoretic and semantic framework, whose main
distinguishing feature is being based on circuits, as opposed to the more
traditional approaches that deal with tree-like objects such as formulas or
sequents. Among its advantages are greater efficiency, flexibility and
expressiveness. This paper presents a detailed elaboration of a deep-inference
cirquent logic, which is naturally and inherently resource conscious. It shows
that classical logic, both syntactically and semantically, is just a special,
conservative fragment of this more general and, in a sense, more basic logic --
the logic of resources in the form of cirquent calculus. The reader will find
various arguments in favor of switching to the new framework, such as arguments
showing the insufficiency of the expressive power of linear logic or other
formula-based approaches to developing resource logics, exponential
improvements over the traditional approaches in both representational and proof
complexities offered by cirquent calculus, and more. Among the main purposes of
this paper is to provide an introductory-style starting point for what, as the
author wishes to hope, might have a chance to become a new line of research in
proof theory -- a proof theory based on circuits instead of formulas.Comment: Significant improvements over the previous version
A Database Interface for Complex Objects
We describe a formal design for a logical query language using psi-terms as data structures to interact effectively and efficiently with a relational database. The structure of psi-terms provides an adequate representation for so-called complex objects. They generalize conventional terms used in logic programming: they are typed attributed structures, ordered thanks to a subtype ordering. Unification of psi-terms is an effective means for integrating multiple inheritance and partial information into a deduction process. We define a compact database representation for psi-terms, representing part of the subtyping relation in the database as well. We describe a retrieval algorithm based on an abstract interpretation of the psi-term unification process and prove its formal correctness. This algorithm is efficient in that it incrementally retrieves only additional facts that are actually needed by a query, and never retrieves the same fact twice
Towards the integration of functions, relations and types in an AI programming language
This paper describes the design and implementation of the programming language PC-Life. This language integrates the functional and the Logic-oriented programming style and feature types supporting inheritance. This combination yields a language particularly suited to knowledge representation, especially for application in computational linguistics
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