The correct answer is A. Negation as failure.
Negation as failure is a form of negation in logic programming that is used to represent the fact that something is not true. It is implemented in Prolog by the not operator, which takes a proposition as its argument and returns true if the proposition is false.
For example, the following Prolog rule states that the atom “foo” is not equal to the atom “bar”:
not(foo = bar).
This rule can be used to prove that the following goal is false:
?- foo = bar.
The Prolog interpreter will search for a proof of this goal, but it will not be able to find one, because the rule “not(foo
= bar)” states that the goal is false. Therefore, the interpreter will return false.Negation as failure is a powerful tool for representing negative information in logic
programs. It can be used to represent a wide variety of negative facts, such as the fact that something does not exist, the fact that something is not true, and the fact that something is not possible.The other options are incorrect because they do not represent negation in Prolog.
- Option B, proposition, is a term in Prolog that represents a fact or a rule.
- Option C, substitution, is a process that is used to replace one term with another in a Prolog expression.
- Option D, negation as success, is a form of negation in logic programming that is used to represent the fact that something is true.