First-order Horn clause
= First-order Horn clause
A <first-order clause> containing at most one positive <first-order literal>. A clause with exactly one positive literal is definite; with no positive literal it is a constraint or goal clause.
= First-order Horn clause
A <first-order clause> containing at most one positive <first-order literal>. A clause with exactly one positive literal is definite; with no positive literal it is a constraint or goal clause.