NO Initial ITS Start location: [1] Program variables: i k 0: [1] -> [2] : k'=nondet, T, cost: 1 1: [2] -> [3] : i'=nondet1, T, cost: 1 2: [3] -> [5] : k >= 0, cost: 1 4: [3] -> [6] : k < 0, cost: 1 7: [4] -> [8] : i >= 0, cost: 1 10: [4] -> [10] : i < 0, cost: 1 3: [5] -> [4] : T, cost: 1 5: [6] -> [7] : i'=-1, T, cost: 1 6: [7] -> [4] : T, cost: 1 8: [8] -> [9] : i'=nondet2, T, cost: 1 9: [9] -> [4] : T, cost: 1 11: [10] -> [11] : i'=2, T, cost: 1 Chained Linear Paths Start location: [1] Program variables: i k 12: [1] -> [3] : i'=nondet1, k'=nondet, T, cost: 1 13: [3] -> [4] : k >= 0, cost: 1 15: [3] -> [4] : i'=-1, k < 0, cost: 1 17: [4] -> [11] : i'=2, i < 0, cost: 1 18: [4] -> [4] : i'=nondet2, i >= 0, cost: 1 Eliminating location [2] by chaining: Applied chaining First rule: [1] -> [2] : k'=nondet, T, cost: 1 Second rule: [2] -> [3] : i'=nondet1, T, cost: 1 New rule: [1] -> [3] : i'=nondet1, k'=nondet, T, cost: 1 Applied deletion Removed the following rules: 0 1 Eliminating location [5] by chaining: Applied chaining First rule: [3] -> [5] : k >= 0, cost: 1 Second rule: [5] -> [4] : T, cost: 1 New rule: [3] -> [4] : k >= 0, cost: 1 Applied deletion Removed the following rules: 2 3 Eliminating location [6] by chaining: Applied chaining First rule: [3] -> [6] : k < 0, cost: 1 Second rule: [6] -> [7] : i'=-1, T, cost: 1 New rule: [3] -> [7] : i'=-1, k < 0, cost: 1 Applied deletion Removed the following rules: 4 5 Eliminating location [7] by chaining: Applied chaining First rule: [3] -> [7] : i'=-1, k < 0, cost: 1 Second rule: [7] -> [4] : T, cost: 1 New rule: [3] -> [4] : i'=-1, k < 0, cost: 1 Applied deletion Removed the following rules: 6 14 Eliminating location [8] by chaining: Applied chaining First rule: [4] -> [8] : i >= 0, cost: 1 Second rule: [8] -> [9] : i'=nondet2, T, cost: 1 New rule: [4] -> [9] : i'=nondet2, i >= 0, cost: 1 Applied deletion Removed the following rules: 7 8 Eliminating location [10] by chaining: Applied chaining First rule: [4] -> [10] : i < 0, cost: 1 Second rule: [10] -> [11] : i'=2, T, cost: 1 New rule: [4] -> [11] : i'=2, i < 0, cost: 1 Applied deletion Removed the following rules: 10 11 Eliminating location [9] by chaining: Applied chaining First rule: [4] -> [9] : i'=nondet2, i >= 0, cost: 1 Second rule: [9] -> [4] : T, cost: 1 New rule: [4] -> [4] : i'=nondet2, i >= 0, cost: 1 Applied deletion Removed the following rules: 9 16 Step with 12 Trace 12[T] Blocked [{}, {}] Step with 13 Trace 12[T], 13[(k >= 0)] Blocked [{}, {}, {}] Step with 17 Trace 12[T], 13[(k >= 0)], 17[(i < 0)] Blocked [{}, {}, {}, {}] Backtrack Trace 12[T], 13[(k >= 0)] Blocked [{}, {}, {17[T]}] Step with 18 Trace 12[T], 13[(k >= 0)], 18[(i >= 0)] Blocked [{}, {}, {17[T]}, {}] Nonterm Start location: [1] Program variables: i k 12: [1] -> [3] : i'=nondet1, k'=nondet, T, cost: 1 13: [3] -> [4] : k >= 0, cost: 1 15: [3] -> [4] : i'=-1, k < 0, cost: 1 17: [4] -> [11] : i'=2, i < 0, cost: 1 18: [4] -> [4] : i'=nondet2, i >= 0, cost: 1 19: [4] -> LoAT_sink : (-nondet2+i <= 0 /\ i >= 0), cost: NONTERM Certificate of Non-Termination Original rule: [4] -> [4] : i'=nondet2, (i >= 0), cost: 1 New rule: [4] -> LoAT_sink : (-nondet2+i <= 0 /\ i >= 0), cost: NONTERM i >= 0 [0]: eventual decrease yields (nondet2 >= 0 /\ i >= 0) i >= 0 [1]: eventual increase yields (-nondet2+i <= 0 /\ i >= 0) Replacement map: {i >= 0 -> (-nondet2+i <= 0 /\ i >= 0)} Step with 19 Trace 12[T], 13[(k >= 0)], 19[(-nondet2+i <= 0 /\ i >= 0)] Blocked [{}, {}, {17[T]}, {19[T]}] Refute Counterexample [ i=0 k=0 ] 12 [ i=0 k=0 ] 13 [ i=i k=k ] 19 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b