from
The Free On-line Dictionary of Computing (8 July 2008)
symbolic inference
The derivation of new facts from known facts and {inference
rules}. This is one of the fundamental operations of
{artificial intelligence} and {logic programming} languages
like {Prolog}.
Inference is a basic part of human reasoning. For example
given that all men are mortal and that Socrates is a man, it
is a trivial step to infer that Socrates is mortal. We might
express these symbolically:
man(X) => mortal(X).
man(socrates).
("if X is a man then X is mortal" and "Socrates is a man").
Here, "man", "mortal" and "socrates" are just arbitrary
symbols which the computer manipulates without reference to or
knowledge of their external meaning. A {forward chaining}
system (a {production system}) could use these to infer the
new fact
mortal(socrates).
simply by matching the left-hand-side of the implication
against the fact and substituting socrates for the variable X.
(1994-10-28)