The Average Person's Axioms of First Order Predicate Logic:

- (A -> B) -> (B -> A)
- (There exists) x A(x) -> (For all) x A(x)
- (A -> C) AND (B -> C) -> (A -> B)

Predicate logic is the study of why the above is funny.

Actually, predicate logic is a mathematical model
for reasoning with
*predicates*
(just as propositional logic is an algebra for reasoning
about the truth of logical expressions).

As in propositional logic,
we can create
*logical expressions*
containing predicates,
manipulate those expressions according to the
*algebraic laws*
of predicate logic, and construct
*proofs*
using rules of inference to deduce new facts from axioms.
In fact,
proofs in predicate logic (based on *unification*) are a form of
*computation*
used in the programming language Prolog.

Although predicate logic is more powerful than propositional logic,
it too has its
*limits*.

last modified Jan 17 1996 / Tom LeBlanc / leblanc@cs.rochester.edu