17 Mar 2005
CS 3243 - Logical Inference
22
Completeness
of Resolution (cont)
nGround
resolution theorem = if S unsatisfiable, RC(S) contains empty clause.
nProve
by proving contrapositive:
ni.e., if RC(S) doesn’t contain empty clause, S is satisfiable
nDo
this by constructing a model:
nFor each Pi,
if there is a clause in RC(S) containing ØPi and all other literals in the clause are false, assign Pi = false
nOtherwise
Pi = true
nThis
assignment of Pi is a model for S.