YES(?, pow(2, b) * a + b + a + 2) Initial complexity problem: 1: T: (1, 1) f(a, b) -> g(a, b) (?, 1) g(a, b) -> g(2*a, b - 1) [ b > 0 ] (?, 1) g(a, b) -> h(a, b) [ 0 >= b ] (?, 1) h(a, b) -> h(a - 1, b) [ a > 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) [ 0 >= b ] strictly and produces the following problem: 2: T: (1, 1) f(a, b) -> g(a, b) (?, 1) g(a, b) -> g(2*a, b - 1) [ b > 0 ] (1, 1) g(a, b) -> h(a, b) [ 0 >= b ] (?, 1) h(a, b) -> h(a - 1, b) [ a > 0 ] start location: f leaf cost: 0 A polynomial rank function with Pol(f) = V_2 Pol(g) = V_2 Pol(h) = V_2 orients all transitions weakly and the transition g(a, b) -> g(2*a, b - 1) [ b > 0 ] strictly and produces the following problem: 3: T: (1, 1) f(a, b) -> g(a, b) (b, 1) g(a, b) -> g(2*a, b - 1) [ b > 0 ] (1, 1) g(a, b) -> h(a, b) [ 0 >= b ] (?, 1) h(a, b) -> h(a - 1, b) [ a > 0 ] start location: f leaf cost: 0 A polynomial rank function with Pol(h) = V_1 and size complexities S("h(a, b) -> h(a - 1, b) [ a > 0 ]", 0-0) = pow(2, b) * a + a S("h(a, b) -> h(a - 1, b) [ a > 0 ]", 0-1) = b S("g(a, b) -> h(a, b) [ 0 >= b ]", 0-0) = pow(2, b) * a + a S("g(a, b) -> h(a, b) [ 0 >= b ]", 0-1) = b S("g(a, b) -> g(2*a, b - 1) [ b > 0 ]", 0-0) = pow(2, b) * a S("g(a, b) -> g(2*a, b - 1) [ b > 0 ]", 0-1) = b S("f(a, b) -> g(a, b)", 0-0) = a S("f(a, b) -> g(a, b)", 0-1) = b orients the transition h(a, b) -> h(a - 1, b) [ a > 0 ] weakly and the transition h(a, b) -> h(a - 1, b) [ a > 0 ] strictly and produces the following problem: 4: T: (1, 1) f(a, b) -> g(a, b) (b, 1) g(a, b) -> g(2*a, b - 1) [ b > 0 ] (1, 1) g(a, b) -> h(a, b) [ 0 >= b ] (pow(2, b) * a + a, 1) h(a, b) -> h(a - 1, b) [ a > 0 ] start location: f leaf cost: 0 Complexity upper bound pow(2, b) * a + b + a + 2 Time: 0.236 sec (SMT: 0.225 sec)