--- pl:prolog:pllib:lesseq_operator [2019/06/27 15:50]
+++ pl:prolog:pllib:lesseq_operator [2019/06/27 15:50] (aktualna)
@@ Linia 1: / Linia 1: @@
+====== Lesseq operator ======
+{{tag>math operators arithmetic}}
+===== Description =====
+The less than or equal relation.
+**Source**:  The Art of Prolog
+===== Download =====
+Program source code: {{lesseq_operator.pl}}
+===== Listing =====
+<code prolog>
+/*
+	X lesseq Y :-  X and Y are natural numbers,
+	  		  such that X is less than or equal to Y.
+We use lesseq to represent the operator rather than cause problems
+with an error message from Prolog about redefining an operator!
+*/
+	:- op(40,xfx, 'lesseq').
+lesseq X :- natural_number(X).
+	s(X) lesseq s(Y) :- X lesseq Y.
+	natural_number(0).
+	natural_number(s(X)) :- natural_number(X).
+%	Program 3.2: The less than or equal relation
+</code>
+===== Comments =====

pl/prolog/pllib/lesseq_operator.txt · ostatnio zmienione: 2019/06/27 15:50 (edycja zewnętrzna)

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