► Chapter 7 presented the syntax and semantics of the propositional and predicate calculi. ► Chapter 8 describes how these logic languages can be used in practical situations. ► Section 8.1 demonstrates predicate calculus reasoning rules and their use in problem-solving. ► Section 8.2 presents the unification algorithm, a methodology for making two different predicate expressions equivalent for reasoning purposes. We conclude the chapter by demonstrating the use of the predicate calculus and unification to implement a knowledge base for financial investment advice.