'\+'/1 /MINERVA/Manual/Reference/Predicates/logic_and_control/not_provable/

succeeds if the goal fails and fails if the goal succeeds. ...

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=>	<=
Darueber	Spitze

See also

','(Conjunction)/2

';'(Disjunction)/2

';'(If-then-else)/2

IF Computer > MINERVA > Manual > Reference > Predicates > Logic and control > '\+'/1

'\+'/1

succeeds if the goal fails and fails if the goal succeeds.

\+(+Goal)
\+ +Goal

'\+'/1 makes negation by failure. That means it succeeds if Goal fails and fails if Goal succeeds.

Arguments

Goal                   goal

Examples

\+fail.	Succeeds.
\+integer(4.76)	Succeeds.
\+((X=either;X=or)),X=neither_nor	Fails.

Standard

This predicate is part of the ISO-Prolog Standard.

See also

abort/0, break/0, call/1, fcall/1, catch/3, ','(conjunction)/2, '!'(cut)/0, ';'(disjunction)/2, fail/0, true/0, halt/0/1, '->'(if-then)/2, ';'(if-then-else)/2, once/1, repeat/0, throw/1.

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document: http://www.ifcomputer.co.jp/MINERVA/Manual/Reference/Predicates/logic_and_control/not_provable/home_de.html
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