MAYBE Initial complexity problem: 1: T: (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ 0 >= Ar_0 + 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ Ar_0 = 0 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ 0 >= Ar_2 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ Ar_2 >= 2 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ Ar_2 = 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ Ar_1 = 0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ 0 >= Ar_1 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ Ar_1 >= 1 ] (Comp: ?, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(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) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ 0 >= Ar_0 + 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ Ar_0 = 0 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ 0 >= Ar_2 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ Ar_2 >= 2 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ Ar_2 = 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ Ar_1 = 0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ 0 >= Ar_1 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ Ar_1 >= 1 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 A polynomial rank function with Pol(f6) = 2 Pol(f9) = 2 Pol(f17) = 1 Pol(f24) = 0 Pol(f0) = 2 Pol(koat_start) = 2 orients all transitions weakly and the transition f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ Ar_2 = 1 ] strictly and produces the following problem: 3: T: (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ 0 >= Ar_0 + 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ Ar_0 = 0 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ 0 >= Ar_2 ] (Comp: ?, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ Ar_2 >= 2 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ Ar_2 = 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ Ar_1 = 0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ 0 >= Ar_1 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ Ar_1 >= 1 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 A polynomial rank function with Pol(f6) = 2 Pol(f9) = 2 Pol(f17) = 1 Pol(f24) = 0 Pol(f0) = 2 Pol(koat_start) = 2 orients all transitions weakly and the transitions f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ Ar_1 = 0 ] f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ Ar_0 = 0 ] f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ Ar_2 >= 2 ] f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ 0 >= Ar_2 ] strictly and produces the following problem: 4: T: (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ 0 >= Ar_0 + 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ Ar_0 >= 1 ] (Comp: 2, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ Ar_0 = 0 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ 0 >= Ar_2 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ Ar_2 >= 2 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ Ar_2 = 1 ] (Comp: 2, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ Ar_1 = 0 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ 0 >= Ar_1 + 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ Ar_1 >= 1 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] start location: koat_start leaf cost: 0 Applied AI with 'oct' on problem 4 to obtain the following invariants: For symbol f17: -X_3 + 1 >= 0 /\ X_3 >= 0 For symbol f6: -X_3 >= 0 /\ X_3 >= 0 For symbol f9: -X_3 >= 0 /\ X_3 >= 0 This yielded the following problem: 5: T: (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_1 >= 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_1 + 1 ] (Comp: 2, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_1 = 0 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ Ar_2 = 1 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ Ar_2 >= 2 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_2 ] (Comp: 2, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_0 = 0 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_0 >= 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_0 + 1 ] start location: koat_start leaf cost: 0 Testing for unsatisfiable constraints removes the following transition from problem 5: f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ Ar_2 >= 2 ] We thus obtain the following problem: 6: T: (Comp: 1, Cost: 0) koat_start(Ar_0, Ar_1, Ar_2) -> Com_1(f0(Ar_0, Ar_1, Ar_2)) [ 0 <= 0 ] (Comp: 1, Cost: 1) f0(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_0, Ar_1, 0)) (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_1, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_1 >= 1 ] (Comp: ?, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f6(Fresh_2, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_1 + 1 ] (Comp: 2, Cost: 1) f9(Ar_0, Ar_1, Ar_2) -> Com_1(f17(Ar_0, 0, 1)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_1 = 0 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, 0)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ Ar_2 = 1 ] (Comp: 2, Cost: 1) f17(Ar_0, Ar_1, Ar_2) -> Com_1(f24(Ar_0, Ar_1, Ar_2)) [ -Ar_2 + 1 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_2 ] (Comp: 2, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f17(0, Ar_1, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_0 = 0 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_3, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ Ar_0 >= 1 ] (Comp: ?, Cost: 1) f6(Ar_0, Ar_1, Ar_2) -> Com_1(f9(Ar_0, Fresh_4, Ar_2)) [ -Ar_2 >= 0 /\ Ar_2 >= 0 /\ 0 >= Ar_0 + 1 ] start location: koat_start leaf cost: 0 Complexity upper bound ? Time: 2.345 sec (SMT: 2.273 sec)