MAYBE Initial complexity problem: 1: T: (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 500 ] (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Ar_0 + 1, Ar_1, Ar_2)) [ 499 >= Ar_0 ] (Comp: ?, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Fresh_1, Fresh_2, Fresh_1)) [ Fresh_1 >= 500 ] (Comp: ?, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Fresh_0 + 1, Ar_1, Fresh_0)) [ 499 >= Fresh_0 ] (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f2(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Repeatedly propagating knowledge in problem 1 produces the following problem: 2: T: (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 500 ] (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Ar_0 + 1, Ar_1, Ar_2)) [ 499 >= Ar_0 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Fresh_1, Fresh_2, Fresh_1)) [ Fresh_1 >= 500 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Fresh_0 + 1, Ar_1, Fresh_0)) [ 499 >= Fresh_0 ] (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f2(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 A polynomial rank function with Pol(f1) = 1 Pol(f3) = 0 Pol(f2) = 1 Pol(koat_start) = 1 orients all transitions weakly and the transition f1(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 500 ] strictly and produces the following problem: 3: T: (Comp: 1, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 500 ] (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Ar_0 + 1, Ar_1, Ar_2)) [ 499 >= Ar_0 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Fresh_1, Fresh_2, Fresh_1)) [ Fresh_1 >= 500 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Fresh_0 + 1, Ar_1, Fresh_0)) [ 499 >= Fresh_0 ] (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f2(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Applied AI with 'oct' on problem 3 to obtain the following invariants: For symbol f1: -X_3 + 499 >= 0 /\ X_1 - X_3 - 1 >= 0 /\ -X_1 - X_3 + 999 >= 0 /\ -X_1 + 500 >= 0 This yielded the following problem: 4: T: (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f2(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Fresh_0 + 1, Ar_1, Fresh_0)) [ 499 >= Fresh_0 ] (Comp: 1, Cost: 1) f2(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Fresh_1, Fresh_2, Fresh_1)) [ Fresh_1 >= 500 ] (Comp: ?, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f1(Ar_0 + 1, Ar_1, Ar_2)) [ -Ar_2 + 499 >= 0 /\ Ar_0 - Ar_2 - 1 >= 0 /\ -Ar_0 - Ar_2 + 999 >= 0 /\ -Ar_0 + 500 >= 0 /\ 499 >= Ar_0 ] (Comp: 1, Cost: 1) f1(Ar_0, Ar_1, Ar_2) -> Com_1(f3(Ar_0, Fresh_3, Ar_2)) [ -Ar_2 + 499 >= 0 /\ Ar_0 - Ar_2 - 1 >= 0 /\ -Ar_0 - Ar_2 + 999 >= 0 /\ -Ar_0 + 500 >= 0 /\ Ar_0 >= 500 ] start location: koat_start leaf cost: 0 Complexity upper bound ? Time: 1.171 sec (SMT: 1.132 sec)