Inductive Logic Programming

Horn clause

• A horn clause is a clause (a disjunction of literals) with at most one positive.
• Definite clause: Horn clauses with exactly one positive literal.
• Fact: Definite clauses without negative literals.

Name	Disjunction form	Implication form	Read intuitively as
Definite clause	¬p ∨ ¬q ∨ ... ∨ ¬t ∨ u	u ← p ∧ q ∧ ... ∧ t	assume that, if p and q and ... and t all hold, then also u holds
Fact	u	u	assume that u holds