## Completeness theorem was not based on whether the order logic in all of predicate

However, there are some sentences of the first order logic that must be true but that do not have the form of tautologies of the propositional logic. As with the tableaux method, a formula is proved by showing that the negation of the formula is unsatisfiable. How can resolution be used to show that a sentence is valid? Proof tree constructed by backward chaining to prove that West is a criminal. It is also possible to restrict the arities of function symbols and predicate symbols, in sufficiently expressive theories. How to pick which pair of literals, one from each sentence, to unify? We can also use classical heuristics before employing the quantum protocol, as in the algorithm described in the previous section. There is a second common approach to defining truth values that does not rely on variable assignment functions. The factors are defined over the cliques of the graph. Groundings are viewed as connected if they can jointly appear in a grounding of some formula of the knowledge base. Lean, it is often convenient to express facts like this as an iterated implication. In the last few clauses certain constants are used in an overloaded manner.