(define
	(:predicates
		(room ?r)
		(ball ?b)
		(gripper ?g)
		(at-robby ?r)
		(at ?b ?r)
		(free ?g)
		(carry ?o ?g)
	)
	(:action move
		:parameters (?from ?to)
		:precondition 
			(and
				(room ?from)
				(room ?to)
				(at-robby ?from)
			)
		:effect 
			(and
				(at-robby ?to)
				(not (at-robby ?from))
			)
	)
	(:action pick
		:parameters (?obj ?room ?gripper)
		:precondition 
			(and
				(ball ?obj)
				(room ?room)
				(gripper ?gripper)
				(at ?obj ?room)
				(at-robby ?room)
				(free ?gripper)
			)
		:effect 
			(and
				(carry ?obj ?gripper)
				(not (at ?obj ?room))
				(not (free ?gripper))
			)
	)
	(:action drop
		:parameters (?obj ?room ?gripper)
		:precondition 
			(and
				(ball ?obj)
				(room ?room)
				(gripper ?gripper)
				(carry ?obj ?gripper)
				(at-robby ?room)
			)
		:effect 
			(and
				(at ?obj ?room)
				(free ?gripper)
				(not (carry ?obj ?gripper))
			)
	)
)