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not

Backward Chaining Goal
Summary

A goal that is satisfied when another goal fails.

Signature

not { condition }*

Arguments

condition

Any backward chaining goal.

Description

If not is used in a backward chaining goal, it succeeds if the condition contained within it fails. In this usage, only one condition is allowed.

If not is used in a forward chaining pre-condition, it succeeds if any of the condition contained within it fail. In this usage, the condition s may only contain expressions normally allowed in forward chaining pre-conditions (object base references and lisp tests).

Examples
(not (truck ?truck driver ?driver) (test ?driver))
See also

test


KnowledgeWorks and Prolog User Guide (Unix version) - 22 Dec 2009

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