MAYBE

Initial complexity problem:
1:	T:
		(Comp: ?, Cost: 1)    f300(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f1(Fresh_27, Fresh_28, Fresh_29, Fresh_30, Fresh_31, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17))
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, 256, Fresh_21, Fresh_22, Fresh_23, Fresh_24, Fresh_25, Fresh_26, Ar_14, Ar_15, Ar_16, Ar_17)) [ Ar_6 >= Ar_5 + 1 /\ X' >= 1 /\ Ar_7 = 256 ]
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Fresh_16, Fresh_17, Fresh_18, Fresh_19, Fresh_20, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17)) [ Ar_6 >= Ar_5 + 1 /\ 0 >= Ar_7 ]
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f3(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Fresh_14, Fresh_15, Ar_10, Ar_11, Ar_12, Ar_13, 0, 0, 0, Ar_17)) [ Ar_5 >= Ar_6 ]
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Fresh_7, Fresh_8, Fresh_9, Fresh_10, Fresh_11, Fresh_12, Ar_7, Ar_7, Ar_7, Fresh_13)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ Ar_7 >= 257 ]
		(Comp: ?, Cost: 1)    f1(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f2(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Fresh_0, Fresh_1, Fresh_2, Fresh_3, Fresh_4, Fresh_5, Ar_7, Ar_7, Ar_7, Fresh_6)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ 255 >= Ar_7 ]
		(Comp: 1, Cost: 0)    koat_start(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17) -> Com_1(f300(Ar_0, Ar_1, Ar_2, Ar_3, Ar_4, Ar_5, Ar_6, Ar_7, Ar_8, Ar_9, Ar_10, Ar_11, Ar_12, Ar_13, Ar_14, Ar_15, Ar_16, Ar_17)) [ 0 <= 0 ]
	start location:	koat_start
	leaf cost:	0

Slicing away variables that do not contribute to conditions from problem 1 leaves variables [Ar_5, Ar_6, Ar_7].
We thus obtain the following problem:
2:	T:
		(Comp: 1, Cost: 0)    koat_start(Ar_5, Ar_6, Ar_7) -> Com_1(f300(Ar_5, Ar_6, Ar_7)) [ 0 <= 0 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f2(Ar_5, Ar_6, Ar_7)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ 255 >= Ar_7 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f2(Ar_5, Ar_6, Ar_7)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ Ar_7 >= 257 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f3(Ar_5, Ar_6, Ar_7)) [ Ar_5 >= Ar_6 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, Ar_7)) [ Ar_6 >= Ar_5 + 1 /\ 0 >= Ar_7 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, 256)) [ Ar_6 >= Ar_5 + 1 /\ X' >= 1 /\ Ar_7 = 256 ]
		(Comp: ?, Cost: 1)    f300(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, Ar_7))
	start location:	koat_start
	leaf cost:	0

Repeatedly propagating knowledge in problem 2 produces the following problem:
3:	T:
		(Comp: 1, Cost: 0)    koat_start(Ar_5, Ar_6, Ar_7) -> Com_1(f300(Ar_5, Ar_6, Ar_7)) [ 0 <= 0 ]
		(Comp: 1, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f2(Ar_5, Ar_6, Ar_7)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ 255 >= Ar_7 ]
		(Comp: 1, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f2(Ar_5, Ar_6, Ar_7)) [ Ar_7 >= 1 /\ Ar_6 >= Ar_5 + 1 /\ Ar_7 >= 257 ]
		(Comp: 1, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f3(Ar_5, Ar_6, Ar_7)) [ Ar_5 >= Ar_6 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, Ar_7)) [ Ar_6 >= Ar_5 + 1 /\ 0 >= Ar_7 ]
		(Comp: ?, Cost: 1)    f1(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, 256)) [ Ar_6 >= Ar_5 + 1 /\ X' >= 1 /\ Ar_7 = 256 ]
		(Comp: 1, Cost: 1)    f300(Ar_5, Ar_6, Ar_7) -> Com_1(f1(Ar_5, Ar_6, Ar_7))
	start location:	koat_start
	leaf cost:	0

Complexity upper bound ?

Time: 0.912 sec (SMT: 0.866 sec)