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