MAYBE Initial complexity problem: 1: T: (?, 1) f0(a, b, c, d, e) -> f2(a, f, c, d, e) [ 0 >= a ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ a >= 2*g + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ f >= 2*g + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ a >= 2*g + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ 2*g >= f + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ 2*g >= a + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ f >= 2*g + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ 2*g >= a + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ 2*g >= f + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(f, b, c, h, f) [ 2*f >= 1 /\ g >= 1 /\ a = 2*f ] (1, 1) f1(a, b, c, d, e) -> f0(a, b, c, d, e) start location: f1 leaf cost: 0 Testing for unsatisfiable constraints removes the following transitions from problem 1: f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ a >= 2*g + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ 2*g >= f + 1 /\ f >= 1 ] f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ 2*g >= a + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ f >= 2*g + 1 /\ f >= 1 ] We thus obtain the following problem: 2: T: (?, 1) f0(a, b, c, d, e) -> f2(a, f, c, d, e) [ 0 >= a ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ a >= 2*g + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ f >= 2*g + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ 2*g >= a + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ 2*g >= f + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(f, b, c, h, f) [ 2*f >= 1 /\ g >= 1 /\ a = 2*f ] (1, 1) f1(a, b, c, d, e) -> f0(a, b, c, d, e) start location: f1 leaf cost: 0 Repeatedly removing leaves of the complexity graph in problem 2 produces the following problem: 3: T: (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ a >= 2*g + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ f >= 2*g + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(3*a + 1, b, f, h, g) [ a >= 1 /\ 2*g >= a + 1 /\ 3*a >= 3*f /\ 3*f >= 3*a /\ 2*g >= f + 1 /\ f >= 1 ] (?, 1) f0(a, b, c, d, e) -> f0(f, b, c, h, f) [ 2*f >= 1 /\ g >= 1 /\ a = 2*f ] (1, 1) f1(a, b, c, d, e) -> f0(a, b, c, d, e) start location: f1 leaf cost: 1 Complexity upper bound ? Time: 0.437 sec (SMT: 0.412 sec)