Henning Christiansen

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This paper is a comment on two recent contributions to Sigplan Notices. In his paperC QThe static semantics !leRC no. 25/4C Brian Meek discusses the relevance of the notion of Qstatic semanticsR. The relation between a variable's declaration and the restrictions on its useC for exampleC is usually classi!ed as static semantics. Meek !nds the designation(More)
A grammar formalism based upon CHR is proposed analogously to the way Definite Clause Grammars are defined and implemented on top of Prolog. These grammars execute as robust bottom-up parsers with an inherent treatment of ambiguity and a high flexibility to model various linguistic phenomena. The formalism extends previous logic programming based grammars(More)
A class of Probabilistic Abductive Logic Programs (PALPs) is introduced and an implementation is developed in CHR for solving abductive problems, providing minimal explanations with their probabilities. Both all-explanations and most-probable-explanations versions are given. Compared with other probabilistic versions of abductive logic programming , the(More)
We present HYPROLOG, a novel integration of Prolog with assumptions and abduction which is implemented in and partly borrows syntax from Constraint Handling Rules (CHR) for integrity constraints. Assumptions are a mechanism inspired by linear logic and taken over from Assumption Grammars. The language shows a novel flexibility in the interaction between the(More)
Integrity constraint and abduction are important in query-answering systems for enhanced query processing and for expressing knowledge in databases. A straightforward characterization of the two is given in a subset of the language CHR ¤ , originally intended for writing constraint solvers to be applied for CLP languages. This subset has a strikingly simple(More)
Using constraint logic techniques, it is made possible to use a well-known metainterpreter backwards as a device for generating programs. A metainterpreter is developed, which provides a sound and complete implementation of the binary demo predicate. Based on it, a general methodology for automated reasoning is proposed and it turns out that a wide range of(More)
Complete checks of database integrity constraints may be prohibitively time consuming, and several methods have been suggested for producing simplified checks for each update. The present approach introduces a set of transformation operators that apply to database integrity constraints with each operator representing a concise, semantics-preserving(More)