MAYBE Initial complexity problem: 1: T: (Comp: ?, Cost: 1) f0(Ar_0) -> Com_1(f5(Fresh_1)) [ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f5(Ar_0 + 1)) [ 19 >= Ar_0 ] (Comp: ?, Cost: 1) f0(Ar_0) -> Com_1(f12(Fresh_0)) [ 0 >= Fresh_0 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f12(Ar_0)) [ Ar_0 >= 20 ] (Comp: 1, Cost: 0) koat_start(Ar_0) -> Com_1(f0(Ar_0)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Repeatedly propagating knowledge in problem 1 produces the following problem: 2: T: (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f5(Fresh_1)) [ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f5(Ar_0 + 1)) [ 19 >= Ar_0 ] (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f12(Fresh_0)) [ 0 >= Fresh_0 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f12(Ar_0)) [ Ar_0 >= 20 ] (Comp: 1, Cost: 0) koat_start(Ar_0) -> Com_1(f0(Ar_0)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 A polynomial rank function with Pol(f0) = 1 Pol(f5) = 1 Pol(f12) = 0 Pol(koat_start) = 1 orients all transitions weakly and the transition f5(Ar_0) -> Com_1(f12(Ar_0)) [ Ar_0 >= 20 ] strictly and produces the following problem: 3: T: (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f5(Fresh_1)) [ Fresh_1 >= 1 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f5(Ar_0 + 1)) [ 19 >= Ar_0 ] (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f12(Fresh_0)) [ 0 >= Fresh_0 ] (Comp: 1, Cost: 1) f5(Ar_0) -> Com_1(f12(Ar_0)) [ Ar_0 >= 20 ] (Comp: 1, Cost: 0) koat_start(Ar_0) -> Com_1(f0(Ar_0)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Applied AI with 'oct' on problem 3 to obtain the following invariants: For symbol f5: X_1 - 1 >= 0 This yielded the following problem: 4: T: (Comp: 1, Cost: 0) koat_start(Ar_0) -> Com_1(f0(Ar_0)) [ 0 <= 0 ] (Comp: 1, Cost: 1) f5(Ar_0) -> Com_1(f12(Ar_0)) [ Ar_0 - 1 >= 0 /\ Ar_0 >= 20 ] (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f12(Fresh_0)) [ 0 >= Fresh_0 ] (Comp: ?, Cost: 1) f5(Ar_0) -> Com_1(f5(Ar_0 + 1)) [ Ar_0 - 1 >= 0 /\ 19 >= Ar_0 ] (Comp: 1, Cost: 1) f0(Ar_0) -> Com_1(f5(Fresh_1)) [ Fresh_1 >= 1 ] start location: koat_start leaf cost: 0 Complexity upper bound ? Time: 0.759 sec (SMT: 0.730 sec)