Forward Checking, example
Variables x, y
Dx = Dy = {1,2,3,4,5}
Constraint x < y - 1
Initially CDx = CDy = {1,2,3,4,5}
If we set x = 2, then:
the only possible values are y = 4, y = 5
so set CDy = {4,5}
If we set x = 4, then
no possible values of y remain, I.e. CDy = { }
retract choice of x = 4 and backtrack
Previous slide
Next slide
Back to first slide
View graphic version