====== Variation ======
{{tag>combinatorics lists}}
===== Description =====
Program create variation without repeated list elements

**Source**:  Guide to Prolog Programming (on-line tutorial)
===== Download =====
Program source code: {{variation.pl}}
===== Listing =====
<code prolog>
varia(0,_,[]).
varia(N,L,[H|Varia]):-N>0,N1 is N-1,delete(H,L,Rest),varia(N1,Rest,Varia).

delete(X,[X|T],T).
delete(X,[H|T],[H|NT]):-delete(X,T,NT).</code>
===== Comments =====