Propagator Groups

This paper introduces propagator groups as an abstraction for controlling the execution of propagators as implementations of constraints. Propagator groups enable users of a constraint programming system to program how propagators within a group are executed. The paper exemplifies propagator groups for controlling both propagation order and propagator interaction. Controlling propagation order is applied to debugging constraint propagation and optimal constraint propagation for Berge-acyclic propagator graphs. Controlling propagator interaction by encapsulating failure and entailment is applied to general reification and constructive disjunction. The paper describes an implementation of propagator groups (based on Gecode) that is applicable to any propagator-centered constraint programming system. Experiments show that groups incur little to no overhead and that the applications of groups are practically usable and efficient.

• Type: Conference
• Year: 2009
• Where: CP
• Authors: Mikael Z. Lagerkvist, Christian Schulte
• Keywords: CP 2009, Paper Exemplifies Propagator, Paper Introduces Propagator, Programming Languages, Propagator Groups