====== If rule ======
{{tag>statements rules}}
===== Description =====
Usage of rule "if"

**Source**:  PROLOG str. 18 Wydawnictwo PLJ Warszawa 1991 ISBN 83-85190-63-5
===== Download =====
Program source code: {{if_rule.pl}}
===== Listing =====
<code prolog>
mezczyzna(pawel).
przystojny(pawel).
jezdzi(pawel, porshe).

lubi(magda, X) :- mezczyzna(X), przystojny(X), jezdzi(X, porshe).</code>
===== Comments =====