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