MAYBE

Initial complexity problem:
1:	T:
		(1, 1)    f3(a, b, c) -> f2(a, b, c)
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ 0 >= a + 1 /\ 0 >= d /\ b >= 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ 0 >= a + 1 /\ 0 >= d /\ 0 >= b ]
		(?, 1)    f2(a, b, c) -> f2(e + 1, b, c) [ d >= 2 /\ 0 >= a + 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ a >= 1 /\ 0 >= d + 2 /\ b >= 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ a >= 1 /\ 0 >= d + 2 /\ 0 >= b ]
		(?, 1)    f2(a, b, c) -> f2(e + 1, b, c) [ d >= 0 /\ a >= 1 ]
		(?, 1)    f2(a, b, c) -> f300(0, b, e) [ 0 >= a + 1 ]
		(?, 1)    f2(a, b, c) -> f300(0, b, e) [ a >= 1 ]
		(?, 1)    f2(a, b, c) -> f300(a, b, e) [ a = 0 ]
	start location:	f3
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 1 produces the following problem:
2:	T:
		(1, 1)    f3(a, b, c) -> f2(a, b, c)
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ 0 >= a + 1 /\ 0 >= d /\ b >= 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ 0 >= a + 1 /\ 0 >= d /\ 0 >= b ]
		(?, 1)    f2(a, b, c) -> f2(e + 1, b, c) [ d >= 2 /\ 0 >= a + 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ a >= 1 /\ 0 >= d + 2 /\ b >= 1 ]
		(?, 1)    f2(a, b, c) -> f2(e - 1, b, c) [ a >= 1 /\ 0 >= d + 2 /\ 0 >= b ]
		(?, 1)    f2(a, b, c) -> f2(e + 1, b, c) [ d >= 0 /\ a >= 1 ]
	start location:	f3
	leaf cost:	3

Complexity upper bound ?

Time: 0.354 sec (SMT: 0.331 sec)