NO Initial ITS Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 1: [2] -> [3] : i > 0, cost: 1 4: [2] -> [5] : i <= 0, cost: 1 2: [3] -> [4] : i'=1+i, T, cost: 1 3: [4] -> [2] : T, cost: 1 Chained Linear Paths Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 4: [2] -> [5] : i <= 0, cost: 1 6: [2] -> [2] : i'=1+i, i > 0, cost: 1 Eliminating location [3] by chaining: Applied chaining First rule: [2] -> [3] : i > 0, cost: 1 Second rule: [3] -> [4] : i'=1+i, T, cost: 1 New rule: [2] -> [4] : i'=1+i, i > 0, cost: 1 Applied deletion Removed the following rules: 1 2 Eliminating location [4] by chaining: Applied chaining First rule: [2] -> [4] : i'=1+i, i > 0, cost: 1 Second rule: [4] -> [2] : T, cost: 1 New rule: [2] -> [2] : i'=1+i, i > 0, cost: 1 Applied deletion Removed the following rules: 3 5 Step with 0 Trace 0[T] Blocked [{}, {}] Step with 4 Trace 0[T], 4[(i <= 0)] Blocked [{}, {}, {}] Backtrack Trace 0[T] Blocked [{}, {4[T]}] Step with 6 Trace 0[T], 6[(i > 0)] Blocked [{}, {4[T]}, {}] Nonterm Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 4: [2] -> [5] : i <= 0, cost: 1 6: [2] -> [2] : i'=1+i, i > 0, cost: 1 7: [2] -> LoAT_sink : (-1+n >= 0 /\ i > 0), cost: NONTERM 8: [2] -> [2] : i'=n+i, (-1+n >= 0 /\ i > 0), cost: 1 Certificate of Non-Termination Original rule: [2] -> [2] : i'=1+i, (i > 0), cost: 1 New rule: [2] -> LoAT_sink : (-1+n >= 0 /\ i > 0), cost: NONTERM i > 0 [0]: monotonic increase yields i > 0 Replacement map: {i > 0 -> i > 0} Loop Acceleration Original rule: [2] -> [2] : i'=1+i, (i > 0), cost: 1 New rule: [2] -> [2] : i'=n+i, (-1+n >= 0 /\ i > 0), cost: 1 i > 0 [0]: monotonic increase yields i > 0 Replacement map: {i > 0 -> i > 0} Step with 7 Trace 0[T], 7[(-1+n >= 0 /\ i > 0)] Blocked [{}, {4[T]}, {7[T]}] Refute Counterexample [ i=1 ] 0 [ i=i ] 7 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b