MAYBE Initial complexity problem: 1: T: (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f25(Ar_0, Ar_1) -> Com_1(f2(Ar_0, Ar_1)) (Comp: ?, Cost: 1) f2(Ar_0, Ar_1) -> Com_1(f2(Ar_0, Ar_1)) (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_2)) [ Ar_0 >= 6 /\ 0 >= Fresh_2 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_1)) [ Ar_0 >= 6 /\ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f27(Ar_0, Ar_1) -> Com_1(f29(Ar_0, Ar_1)) (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f19(Ar_0 - 1, Ar_1)) [ Ar_0 >= 3 ] (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f9(Ar_0, Ar_1)) [ 2 >= Ar_0 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f19(Ar_0, 0)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f0(Ar_0, Ar_1) -> Com_1(f9(Fresh_0, Ar_1)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1) -> Com_1(f0(Ar_0, Ar_1)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Testing for reachability in the complexity graph removes the following transitions from problem 1: f25(Ar_0, Ar_1) -> Com_1(f2(Ar_0, Ar_1)) f2(Ar_0, Ar_1) -> Com_1(f2(Ar_0, Ar_1)) f27(Ar_0, Ar_1) -> Com_1(f29(Ar_0, Ar_1)) We thus obtain the following problem: 2: T: (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f9(Ar_0, Ar_1)) [ 2 >= Ar_0 ] (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f19(Ar_0 - 1, Ar_1)) [ Ar_0 >= 3 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f19(Ar_0, 0)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_1)) [ Ar_0 >= 6 /\ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_2)) [ Ar_0 >= 6 /\ 0 >= Fresh_2 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f0(Ar_0, Ar_1) -> Com_1(f9(Fresh_0, Ar_1)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1) -> Com_1(f0(Ar_0, Ar_1)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Repeatedly propagating knowledge in problem 2 produces the following problem: 3: T: (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f9(Ar_0, Ar_1)) [ 2 >= Ar_0 ] (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f19(Ar_0 - 1, Ar_1)) [ Ar_0 >= 3 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f19(Ar_0, 0)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_1)) [ Ar_0 >= 6 /\ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_2)) [ Ar_0 >= 6 /\ 0 >= Fresh_2 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Ar_1)) [ 5 >= Ar_0 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1) -> Com_1(f9(Fresh_0, Ar_1)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1) -> Com_1(f0(Ar_0, Ar_1)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Applied AI with 'oct' on problem 3 to obtain the following invariants: For symbol f19: -X_2 >= 0 /\ X_2 >= 0 This yielded the following problem: 4: T: (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1) -> Com_1(f0(Ar_0, Ar_1)) [ 0 <= 0 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1) -> Com_1(f9(Fresh_0, Ar_1)) (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_2)) [ Ar_0 >= 6 /\ 0 >= Fresh_2 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f10(Ar_0, Fresh_1)) [ Ar_0 >= 6 /\ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1) -> Com_1(f19(Ar_0, 0)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ 5 >= Ar_0 ] (Comp: ?, Cost: 1) f10(Ar_0, Ar_1) -> Com_1(f9(Ar_0 + 1, Ar_1)) [ Ar_0 >= 6 ] (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f19(Ar_0 - 1, Ar_1)) [ -Ar_1 >= 0 /\ Ar_1 >= 0 /\ Ar_0 >= 3 ] (Comp: ?, Cost: 1) f19(Ar_0, Ar_1) -> Com_1(f9(Ar_0, Ar_1)) [ -Ar_1 >= 0 /\ Ar_1 >= 0 /\ 2 >= Ar_0 ] start location: koat_start leaf cost: 0 Complexity upper bound ? Time: 2.637 sec (SMT: 2.554 sec)