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CW 481
Jon Sneyers, Peter Van Weert, Tom Schrijvers, Bart Demoen
Aggregates in CHR
Abstract
We propose an extension of the Constraint Handling Rules language
with aggregates like sum, count,
findall, and min in the heads of rules.
We define the semantics of aggregate expressions formally and informally.
Our prototype implementation as a source-to-source preprocessor
allows both on-demand and incremental computation of
nested aggregate expressions over guarded conjunctions of constraints.
Case studies demonstrate that by using aggregates, the program size can be
significantly reduced, with only a small constant run-time overhead.
