YES(?, 149*a + 6*a^2 + 336) Initial complexity problem: 1: T: (?, 1) eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ] (?, 1) eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\ b >= 1 /\ a >= b ] (?, 1) eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\ b >= 1 /\ b >= a + 1 ] (1, 1) start(a, b) -> eval1(a, b) start location: start leaf cost: 0 A polynomial rank function with Pol(eval1) = 2*V_1 + 5 Pol(eval2) = 2*V_1 + 2 Pol(start) = 2*V_1 + 5 orients all transitions weakly and the transitions eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\ b >= 1 /\ b >= a + 1 ] eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ] strictly and produces the following problem: 2: T: (2*a + 5, 1) eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ] (?, 1) eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\ b >= 1 /\ a >= b ] (2*a + 5, 1) eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\ b >= 1 /\ b >= a + 1 ] (1, 1) start(a, b) -> eval1(a, b) start location: start leaf cost: 0 A polynomial rank function with Pol(eval2) = V_1 - V_2 + 1 and size complexities S("start(a, b) -> eval1(a, b)", 0-0) = a S("start(a, b) -> eval1(a, b)", 0-1) = b S("eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\\ b >= 1 /\\ b >= a + 1 ]", 0-0) = 3*a + 63 S("eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\\ b >= 1 /\\ b >= a + 1 ]", 0-1) = ? S("eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\\ b >= 1 /\\ a >= b ]", 0-0) = 3*a + 63 S("eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\\ b >= 1 /\\ a >= b ]", 0-1) = ? S("eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ]", 0-0) = 3*a + 63 S("eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ]", 0-1) = 1 orients the transition eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\ b >= 1 /\ a >= b ] weakly and the transition eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\ b >= 1 /\ a >= b ] strictly and produces the following problem: 3: T: (2*a + 5, 1) eval1(a, b) -> eval2(a + 1, 1) [ a >= 0 ] (6*a^2 + 145*a + 325, 1) eval2(a, b) -> eval2(a, b + 1) [ a >= 0 /\ b >= 1 /\ a >= b ] (2*a + 5, 1) eval2(a, b) -> eval1(a - 2, b) [ a >= 0 /\ b >= 1 /\ b >= a + 1 ] (1, 1) start(a, b) -> eval1(a, b) start location: start leaf cost: 0 Complexity upper bound 149*a + 6*a^2 + 336 Time: 0.139 sec (SMT: 0.131 sec)