====== Descendant ======
{{tag>family}}
===== Description =====
Program use recursion in Prolog to show ancestor-descendant relations

**Source**:  Learn prolog now!, 2001, (course available on-line)
===== Download =====
Program source code: {{descendant.pl}}
===== Listing =====
<code prolog>
child(martha,charlotte).
child(charlotte,caroline).
child(caroline,laura).
child(laura,rose).

descend(X,Y):-child(X,Y).
descend(X,Y):-child(X,Z),
	      descend(Z,Y).</code>
===== Comments =====