What are the forms of Hornclause?

Hornclause is defines as, it is a logical formula for particular rule which gives a useful parameters for a logical programming. Hornclause is a clause with one positive literals.

Different form of hornclause are:

Null clause: Null clause is that with 0 negative and 0 positive literals which appears at the end of a resolution proof. A fact or unit clause: Unit clause is defined as literals, which contain 1 positive literals and 0 negative literals. A negated goal: It is defined as negated goal is the negation of the statements to be proved with at least 1 negative and one positive literals.