YES(?, pow(2, a) + a + 2) Initial complexity problem: 1: T: (1, 1) f(a, b) -> g(a, 1) (?, 1) g(a, b) -> g(a - 1, 2*b) [ a > 0 ] (?, 1) g(a, b) -> h(a, b) [ a <= 0 ] (?, 1) h(a, b) -> h(a, b - 1) [ b > 0 ] start location: f leaf cost: 0 A polynomial rank function with Pol(f) = 1 Pol(g) = 1 Pol(h) = -1 orients all transitions weakly and the transition g(a, b) -> h(a, b) [ a <= 0 ] strictly and produces the following problem: 2: T: (1, 1) f(a, b) -> g(a, 1) (?, 1) g(a, b) -> g(a - 1, 2*b) [ a > 0 ] (1, 1) g(a, b) -> h(a, b) [ a <= 0 ] (?, 1) h(a, b) -> h(a, b - 1) [ b > 0 ] start location: f leaf cost: 0 A polynomial rank function with Pol(f) = V_1 Pol(g) = V_1 Pol(h) = V_1 orients all transitions weakly and the transition g(a, b) -> g(a - 1, 2*b) [ a > 0 ] strictly and produces the following problem: 3: T: (1, 1) f(a, b) -> g(a, 1) (a, 1) g(a, b) -> g(a - 1, 2*b) [ a > 0 ] (1, 1) g(a, b) -> h(a, b) [ a <= 0 ] (?, 1) h(a, b) -> h(a, b - 1) [ b > 0 ] start location: f leaf cost: 0 A polynomial rank function with Pol(h) = V_2 and size complexities S("h(a, b) -> h(a, b - 1) [ b > 0 ]", 0-0) = a S("h(a, b) -> h(a, b - 1) [ b > 0 ]", 0-1) = pow(2, a) S("g(a, b) -> h(a, b) [ a <= 0 ]", 0-0) = a S("g(a, b) -> h(a, b) [ a <= 0 ]", 0-1) = pow(2, a) S("g(a, b) -> g(a - 1, 2*b) [ a > 0 ]", 0-0) = a S("g(a, b) -> g(a - 1, 2*b) [ a > 0 ]", 0-1) = pow(2, a) S("f(a, b) -> g(a, 1)", 0-0) = a S("f(a, b) -> g(a, 1)", 0-1) = 1 orients the transition h(a, b) -> h(a, b - 1) [ b > 0 ] weakly and the transition h(a, b) -> h(a, b - 1) [ b > 0 ] strictly and produces the following problem: 4: T: (1, 1) f(a, b) -> g(a, 1) (a, 1) g(a, b) -> g(a - 1, 2*b) [ a > 0 ] (1, 1) g(a, b) -> h(a, b) [ a <= 0 ] (pow(2, a), 1) h(a, b) -> h(a, b - 1) [ b > 0 ] start location: f leaf cost: 0 Complexity upper bound pow(2, a) + a + 2 Time: 0.239 sec (SMT: 0.229 sec)