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)
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)
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)
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)
Efficient and incremental maintenance of integrity constraints involving recursive views is a difficult issue that has received some attention in the past years, but for which no widely accepted solution exists yet. In this paper a technique is proposed for compiling such integrity constraints into incremental and optimized tests specialized for given(More)