Horn Clause Hall Statement

application

Logician Alfred Horn proposed such a concept to facilitate logical reasoning.

concept

An arbitrary clause is defined as follows:

A1, A2, …, An -> B1，B2, …, Bm

Among them: left condition $A$ is与the relationship, the conclusion on the right is$B$ is或the relationship.
It can be seen that a clause can have multiple conclusions. If a clause has at most one conclusion, then this kind of clause is calledhorn clause.
E.g:

1.parent(X, Z), parent(Z, Y) -> grandparent(X, Y)
2.good(X), bad(X) ->
3.human(X) -> male(X), female(X)

Where 1 and 2 are both horn clause, 3 is not. Because clause1 has 1 conclusion, clause2 has 0 conclusions, and clause3 has 2 conclusions.

Some related conclusions:

The sentences mentioned below are all horn clause.

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-> B

Of which B Yongzhen

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A ->

Of which A is forever

In addition, the one with a conclusion in the horn clause is called headed horn clause, and the one with no conclusion is called headless horn clause.

In addition, many of the inference rules you have seen are headed horn clausein the form:

A1, A2, …, An -> B

Reference: http://www.blogjava.net/Javawind/archive/2007/12/12/167108.html