(define (domain gripper)
(:requirements :strips)
(:predicates (on ?x ?y)
             (on-table ?x)
             (clear ?x)
             (holding ?x)
             (grip-empty))


(:action pick-up
:parameters (?x)
:precondition (and (clear ?x) (on-table ?x) (grip-empty))
:effect (and (not (on-table ?x))
             (not (clear ?x))
             (not (grip-empty))
             (holding ?x)))

(:action unstack
:parameters (?top ?below)
:precondition (and (on ?top ?below) (clear ?top) (grip-empty))
:effect (and (holding ?top)
             (clear ?below)
             (not (clear ?top))
             (not (grip-empty))
             (not (on ?top ?below))))

(:action put-down
:parameters (?x)
:precondition (holding ?x)
:effect (and (on-table ?x)
             (clear ?x)
             (grip-empty)
             (not (holding ?x))))

(:action stack
:parameters (?top ?below)
:precondition (and (holding ?top) (clear ?below))
:effect (and (not (holding ?top))
             (not (clear ?below))
             (clear ?top)
             (grip-empty)
             (on ?top ?below)))
)