17 Feb 2005
CS 3243 - Constraint Satisfaction
35
Arc Consistency Propagation
nWhen we
remove a value from Dx, we may
get new removals because of
it
nE.g.
Dx = {1,4,5}, Dy = {1, 2, 3}, Dz= {2, 3, 4, 5}
nx
> y, z > x
nAs
before we can remove 1 from Dx, so Dx = {4,5}
nBut
now there is no support for Dz = 2,3,4
nSo
we can remove those values, Dz = {5}, so
z=5
nBefore
AC applied to y-x, we could not change Dz
nThis
can cause a chain reaction