Check the following formulas for satisfiability using the Horn's formula satisfiability test. If you verify that the formula is satisfiable, then present a model for it. Justify.
3.1. ((P ^ Q ^ S) → P) ^ ((Q ^ R) → P) ^ ((P ^ S)→S)
3.2. Q ^ S ^ -W ^ (-P V -Q v V v -S) ^ (S v -V) ^ R
