Logic Program Clause

A Logic Program Clause is a logical rule in a logic program.

• See: Linguistic Clause.

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References

2011

• (Sammut & Webb, 2011) ⇒ Claude Sammut (editor), and Geoffrey I. Webb (editor). (2011). “Clause.” In: (Sammut & Webb, 2011) p.178
  • QUOTE: A clause is a logical rule in a logic program. Formally, a clause is a disjunction of (possibly negated) literals, such as grandfather(x,y)∨¬father(x,z)∨¬parent(z,y).

    In the logic programming language Prolog this clause is written as:
    grandfather(X,Y) :- father(X,Z),
    parent(Z,Y).

    The part to the left of :- (“if”) is the head of the clause, and the right part is its body. Informally, the clause asserts the truth of the head given the truth of the body. A clause with exactly one literal in the head is called a Horn clause or definite clause; logic programs mostly consist of definite clauses. A clause without a body is also called a fact; a clause without a head is also called a denial, or a query in a proof by refutation. The clause without head or body is called the empty clause: it signifies inconsistency or falsehood and is denoted □ . Given a set of clauses, the resolution inference rule can be used to deduce logical consequences and answe ...

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