| proposed by | Toby Walsh tw@cs.york.ac.uk |
(V1,P1,V2,P2,V3,P3,V4,P4) = {(r,r,g,g,r,r,g,g), (ry,r,y,r,ry,r,y,r), (g,g,r,r,g,g,r,r), (y,r,ry,r,y,r,ry,r)}
The problem has relative few constraints, but each is very tight. Local
propagation appears to be rather ineffective on this problem.