MAYBE

Initial complexity problem:
1:	T:
		(Comp: ?, Cost: 1)    f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f3(Ar_0, Fresh_0, Ar_2, Ar_3)) [ Ar_0 >= 10 ]
		(Comp: ?, Cost: 1)    f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(Ar_0 - 1, Ar_1, Ar_0, Ar_3)) [ 9 >= Ar_0 ]
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(-1, Ar_1, Ar_2, -1)) [ 9 >= Ar_0 ]
		(Comp: ?, Cost: 1)    f2(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(0, Ar_1, Ar_2, Ar_3))
		(Comp: 1, Cost: 0)    koat_start(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3)) [ 0 <= 0 ]
	start location:	koat_start
	leaf cost:	0

Testing for reachability in the complexity graph removes the following transitions from problem 1:
	f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f3(Ar_0, Fresh_0, Ar_2, Ar_3)) [ Ar_0 >= 10 ]
	f1(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(-1, Ar_1, Ar_2, -1)) [ 9 >= Ar_0 ]
We thus obtain the following problem:
2:	T:
		(Comp: ?, Cost: 1)    f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(Ar_0 - 1, Ar_1, Ar_0, Ar_3)) [ 9 >= Ar_0 ]
		(Comp: ?, Cost: 1)    f2(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(0, Ar_1, Ar_2, Ar_3))
		(Comp: 1, Cost: 0)    koat_start(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3)) [ 0 <= 0 ]
	start location:	koat_start
	leaf cost:	0

Repeatedly propagating knowledge in problem 2 produces the following problem:
3:	T:
		(Comp: ?, Cost: 1)    f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(Ar_0 - 1, Ar_1, Ar_0, Ar_3)) [ 9 >= Ar_0 ]
		(Comp: 1, Cost: 1)    f2(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(0, Ar_1, Ar_2, Ar_3))
		(Comp: 1, Cost: 0)    koat_start(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3)) [ 0 <= 0 ]
	start location:	koat_start
	leaf cost:	0

Applied AI with 'oct' on problem 3 to obtain the following invariants:
  For symbol f0: -X_1 >= 0


This yielded the following problem:
4:	T:
		(Comp: 1, Cost: 0)    koat_start(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3)) [ 0 <= 0 ]
		(Comp: 1, Cost: 1)    f2(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(0, Ar_1, Ar_2, Ar_3))
		(Comp: ?, Cost: 1)    f0(Ar_0, Ar_1, Ar_2, Ar_3) -> Com_1(f0(Ar_0 - 1, Ar_1, Ar_0, Ar_3)) [ -Ar_0 >= 0 /\ 9 >= Ar_0 ]
	start location:	koat_start
	leaf cost:	0

Complexity upper bound ?

Time: 0.688 sec (SMT: 0.657 sec)