YES(?, 3)

Initial complexity problem:
1:	T:
		(?, 1)    start(a, b, c, d) -> lbl41(e, b, c, d) [ a = b /\ c = d ]
		(?, 1)    lbl41(a, b, c, d) -> stop(a, b, a, d) [ c = d ]
		(1, 1)    start0(a, b, c, d) -> start(b, b, d, d)
	start location:	start0
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 1 produces the following problem:
2:	T:
		(none)
	start location:	start0
	leaf cost:	3

Complexity upper bound 3

Time: 0.013 sec (SMT: 0.012 sec)