Constraint Propagation Example Graph Coloring R G. B Different-color constraint Initial Domains Each undirected constraint arc denotes two directed constraint arcs Constraint Propagation Example RG Graph coloring xgtDifferent-color constraint ( R,66 Arc examined value deleted G Arcs to examine V-VoV-VoV. Introduce queue of arcs to be examined Start by adding all arcs to the queue7 Constraint Propagation Example R,G,B R, G G Graph Coloring Initial Domains Different-color constraint V1 V2 V3 Each undirected constraint arc denotes two directed constraint arcs. 8 Constraint Propagation Example R,G,B R, G G Different-color constraint V1 V2 V3 Arc examined Value deleted R,G,B R, G G V2 V3 V1 Graph Coloring Initial Domains Arcs to examine V1-V2, V1-V3, V2-V3 • Introduce queue of arcs to be examined. • Start by adding all arcs to the queue