Given a set of clauses F1 &and F2 &and ... &and Fn &and ¬ G, each clause restricts the portion of the space in which an interpretation satisfying the formula could lie.
A resolution step defines a new (perhaps
better described) space in which any solution must lie; if the
space is empty (□), the formula must be unsatisfiable.
Resolution step: (P &or &alpha) &and (¬ P &or &beta) &rarr
(&alpha &or &beta)
