PROLOG was introduced in 1972. It was based on the predicate calculus and
represented a new paradigm in programming languages-logic programming.
PROLOG is used mainly in artificial intelligence research and is considered
by some to be an attempt to create intelligent machines by moving away
from imperative languages.
Source: "Concepts of Programming Languages" by Robert W. Sebesta,
Benjamin/Cummings Publishing Company, Inc, 1993