Abstract
We show how the language Constraint Handling Rules (CHR), a high-level logic language for the implementation of constraint solvers, can be slightly extended to become a general-purpose logic programming language with an expressive power subsuming the expressive ower of Horn clause programs with SLD resolution. The extended language, called “CHR∀”, retains however the extra features of CHR, e.g., committed choice and matching, which axe important for other purposes, especially for efficiently solving constraints. CHR∀ turns out to be a very flexible query language in the sense that it supports several (constraint) logic programming paradigms and allows to mix them in a single program. In particular, it supports top-down query evaluation and also bottom-up evaluation as it is frequently used in (disjunctive) deductive databases.
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© 1998 Springer-Verlag Berlin Heidelberg
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Abdennadher, S., Schütz, H. (1998). CHR∀: A flexible query language. In: Andreasen, T., Christiansen, H., Larsen, H.L. (eds) Flexible Query Answering Systems. FQAS 1998. Lecture Notes in Computer Science, vol 1495. Springer, Berlin, Heidelberg. https://doi.org/10.1007/BFb0055987
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DOI: https://doi.org/10.1007/BFb0055987
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