First-order logic is a type of Predicate Logic in which predicates take only individuals as arguments and quantifiers only bind individual variables. '' First-order logic is distinguished from propositional logic by its use of quantifiers; each interpretation of first-order logic includes a domain of discourse over which the quantifiers range. Briefly, first-order logic is distinguished from higher-order logics in that quantification is allowed only over atomic entities (individuals but not sets).'' * http://en.wikipedia.org/wiki/First-order_logic Related: * PredicateLogic * BooleanLogic * FuzzyLogic * ProofTheory * SymbolicLogic. ---- CategoryLogic