negation by failure
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negation by failure
An extralogical feature of
Prolog and other
logic programming languages in which failure of
unification is
treated as establishing the negation of a
relation. For
example, if Ronald Reagan is not in our
database and we
asked if he was an American, Prolog would answer "no".
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)
References in periodicals archive
Let us call this program [[PI].sub.1] and consider its modification [[PI].sub.2], in which the "negation as failure" symbol \+ is inserted in front of the second atom in the body of the rule:
But there are cases when the circularity of the above description of negation as failure makes it confusing.
His argumentation systems can formalize and make inference on default reasoning, autoepistemic reasoning, theory formation, circumscription,
negation as failure, and assumption-based reasoning.
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