next up previous contents
Next: fail/0 Up: Some Useful Predicates Previous: Some Useful Predicates

true/0

Always succeeds. 

 
father(jim,fred).
is logically equivalent to 
 
father(jim,fred):-


		       true.
That is, any unit clause is equivalent to a non-unit clause with a single subgoal true in the body.


Paul Brna
Mon May 24 20:14:48 BST 1999