YES(?, 4*a + 9)

Initial complexity problem:
1:	T:
		(1, 1)    start(a) -> a(a) [ a >= 1 ]
		(1, 1)    start(a) -> a(a) [ a >= 2 ]
		(1, 1)    start(a) -> a(a) [ a >= 4 ]
		(?, 1)    a(a) -> a(b) [ 2*b >= 2 /\ a = 2*b ]
		(?, 1)    a(a) -> a(b) [ 2*b >= 1 /\ a = 2*b + 1 ]
	start location:	start
	leaf cost:	0

A polynomial rank function with
	Pol(start) = 2*V_1 - 3
	Pol(a) = 2*V_1 - 3
orients all transitions weakly and the transitions
	a(a) -> a(b) [ 2*b >= 2 /\ a = 2*b ]
	a(a) -> a(b) [ 2*b >= 1 /\ a = 2*b + 1 ]
strictly and produces the following problem:
2:	T:
		(1, 1)          start(a) -> a(a) [ a >= 1 ]
		(1, 1)          start(a) -> a(a) [ a >= 2 ]
		(1, 1)          start(a) -> a(a) [ a >= 4 ]
		(2*a + 3, 1)    a(a) -> a(b) [ 2*b >= 2 /\ a = 2*b ]
		(2*a + 3, 1)    a(a) -> a(b) [ 2*b >= 1 /\ a = 2*b + 1 ]
	start location:	start
	leaf cost:	0

Complexity upper bound 4*a + 9

Time: 0.069 sec (SMT: 0.066 sec)