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