  In this paper, we discussed CNF-SAT problem (NP-Complete problem) and
analysis two solutions that can solve the problem, the PL-Resolution algorithm
and the WalkSAT algorithm. PL-Resolution is a sound and complete algorithm that
can be used to determine satisfiability and unsatisfiability with certainty.
WalkSAT can determine satisfiability if it finds a model, but it cannot
guarantee to find a model even there exists one. However, WalkSAT is much
faster than PL-Resolution, which makes WalkSAT more practical; and we have
analysis the performance between these two algorithms, and the performance of
WalkSAT is acceptable if the problem is not so hard.
