MAYBE

Initial complexity problem:
1:	T:
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f26(a, b, c) -> f27(a, b, c)
		(?, 1)    f27(a, b, c) -> f27(a, b, c)
		(?, 1)    f29(a, b, c) -> f32(a, b, c)
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ a >= 3 ]
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ 2 >= a ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	0

Repeatedly removing leaves of the complexity graph in problem 1 produces the following problem:
2:	T:
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f26(a, b, c) -> f27(a, b, c)
		(?, 1)    f27(a, b, c) -> f27(a, b, c)
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ a >= 3 ]
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ 2 >= a ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

Testing for reachability in the complexity graph removes the following transitions from problem 2:
	f26(a, b, c) -> f27(a, b, c)
	f27(a, b, c) -> f27(a, b, c)
We thus obtain the following problem:
3:	T:
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ 2 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ a >= 3 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ a >= 6 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

Applied AI with 'oct' on problem 3 to obtain the following invariants:
  For symbol f20: X_2 - 1 >= 0 /\ -X_1 + X_2 + 4 >= 0 /\ -X_1 + 5 >= 0


This yielded the following problem:
4:	T:
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ]
	start location:	f0
	leaf cost:	1

By chaining the transition f11(a, b, c) -> f14(a, b, c) [ a >= 6 ] with all transitions in problem 4, the following new transition is obtained:
	f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
We thus obtain the following problem:
5:	T:
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ]
	start location:	f0
	leaf cost:	1

Testing for reachability in the complexity graph removes the following transition from problem 5:
	f14(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
We thus obtain the following problem:
6:	T:
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(?, 1)    f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

By chaining the transition f11(a, b, c) -> f14(a, b, c) [ 5 >= a /\ 0 >= b ] with all transitions in problem 6, the following new transition is obtained:
	f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
We thus obtain the following problem:
7:	T:
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 1)    f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

Testing for reachability in the complexity graph removes the following transition from problem 7:
	f14(a, b, c) -> f11(a + 1, d, c) [ 5 >= a ]
We thus obtain the following problem:
8:	T:
		(?, 1)    f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

By chaining the transition f20(a, b, c) -> f11(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a ] with all transitions in problem 8, the following new transitions are obtained:
	f20(a, b, c) -> f11(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d ]
	f20(a, b, c) -> f20(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ d >= 1 ]
We thus obtain the following problem:
9:	T:
		(?, 3)    f20(a, b, c) -> f11(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d ]
		(?, 2)    f20(a, b, c) -> f20(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ d >= 1 ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

By chaining the transition f20(a, b, c) -> f11(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d ] with all transitions in problem 9, the following new transitions are obtained:
	f20(a, b, c) -> f11(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' ]
	f20(a, b, c) -> f20(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ d' >= 1 ]
We thus obtain the following problem:
10:	T:
		(?, 5)    f20(a, b, c) -> f11(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' ]
		(?, 4)    f20(a, b, c) -> f20(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ d' >= 1 ]
		(?, 2)    f20(a, b, c) -> f20(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ d >= 1 ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

By chaining the transition f20(a, b, c) -> f11(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' ] with all transitions in problem 10, the following new transitions are obtained:
	f20(a, b, c) -> f11(a + 3, d''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' ]
	f20(a, b, c) -> f20(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ d'' >= 1 ]
We thus obtain the following problem:
11:	T:
		(?, 7)    f20(a, b, c) -> f11(a + 3, d''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' ]
		(?, 6)    f20(a, b, c) -> f20(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ d'' >= 1 ]
		(?, 4)    f20(a, b, c) -> f20(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ d' >= 1 ]
		(?, 2)    f20(a, b, c) -> f20(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ d >= 1 ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

By chaining the transition f20(a, b, c) -> f11(a + 3, d''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' ] with all transitions in problem 11, the following new transitions are obtained:
	f20(a, b, c) -> f11(a + 4, d'''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' /\ 5 >= a + 3 /\ 0 >= d''' ]
	f20(a, b, c) -> f20(a + 3, d''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' /\ 5 >= a + 3 /\ d''' >= 1 ]
We thus obtain the following problem:
12:	T:
		(?, 9)    f20(a, b, c) -> f11(a + 4, d'''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' /\ 5 >= a + 3 /\ 0 >= d''' ]
		(?, 8)    f20(a, b, c) -> f20(a + 3, d''', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ 0 >= d'' /\ 5 >= a + 3 /\ d''' >= 1 ]
		(?, 6)    f20(a, b, c) -> f20(a + 2, d'', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ 0 >= d' /\ 5 >= a + 2 /\ d'' >= 1 ]
		(?, 4)    f20(a, b, c) -> f20(a + 1, d', c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ 0 >= d /\ 5 >= a + 1 /\ d' >= 1 ]
		(?, 2)    f20(a, b, c) -> f20(a, d, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ 2 >= a /\ 5 >= a /\ d >= 1 ]
		(?, 1)    f20(a, b, c) -> f20(a - 1, b, c) [ b - 1 >= 0 /\ -a + b + 4 >= 0 /\ -a + 5 >= 0 /\ a >= 3 ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ 5 >= a /\ 0 >= b ]
		(?, 2)    f11(a, b, c) -> f11(a + 1, d, c) [ a >= 6 ]
		(?, 1)    f11(a, b, c) -> f20(a, b, c) [ 5 >= a /\ b >= 1 ]
		(1, 1)    f0(a, b, c) -> f11(d, e, d)
	start location:	f0
	leaf cost:	1

Complexity upper bound ?

Time: 1.872 sec (SMT: 1.762 sec)