Logic Programming and Prolog Chapter 3 Notes

Informal Introduction

Question: Who is proud?

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Refutation in Predicate Logic

Note that a program clause written as

p(A, B):-
    q(A, C),
    r(B, C).

can be rewritten as:
$$
\forall A, B, C (p(A, B)\or \neg q(A, C) \or \neg r(B, C))
$$
i.e. left hand side literal is positive, while all right hand side literals are negative

• Note also that all variables are universally quantified in a clause.