Horn clause form is a sublanguage of first-order predicate logic.
It is particularly convenient for manipulation by
computer and a successful programming language Prolog,
from programming in logic,
has been based on it.
Predicate logic is closely linked to the theory of relations.
Prolog is therefore suitable for use with relational databases
and has given rise to the field of deductive databases.
Prolog is also much used in artificial intelligence applications.
© L. Allison, Dept. Computer Science, Monash University