Question about the variables declared in derived predicates

[nvannaprathip]

I tested with the following example and the parser say that ?x is undefined.

(:derived  (TEST_5 ?z)  (TEST_4 ?x ?y)    )

The question is the number of variables declared in derived predicate (TEST_5 ?z) must be exactly the same as variables used in the basic predicate (TEST_4 ?x ?y) ?

I am very new to PDDL, I tried to apply the :derived in my project. And I saw the example from http://www.sciencedirect.com/science/article/pii/S0004370205000810 and test with your parser. The test result is not as I thought. However, please help advising that. Thank you very much.

[pellierd]

All the variables used in the body of the derived predicates have to be bound.