NO Initial ITS Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 1: [2] -> [3] : (i < 0 \/ i > 0), cost: 1 14: [2] -> [13] : (i <= 0 /\ i >= 0), cost: 1 2: [3] -> [5] : -5+i > 0, cost: 1 5: [3] -> [7] : -5+i <= 0, cost: 1 13: [4] -> [2] : T, cost: 1 3: [5] -> [6] : i'=1+i, T, cost: 1 4: [6] -> [4] : T, cost: 1 6: [7] -> [9] : 5+i < 0, cost: 1 9: [7] -> [11] : 5+i >= 0, cost: 1 12: [8] -> [4] : T, cost: 1 7: [9] -> [10] : i'=-1+i, T, cost: 1 8: [10] -> [8] : T, cost: 1 10: [11] -> [12] : i'=0, T, cost: 1 11: [12] -> [8] : T, cost: 1 Chained Linear Paths Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 1: [2] -> [3] : (i < 0 \/ i > 0), cost: 1 14: [2] -> [13] : (i <= 0 /\ i >= 0), cost: 1 5: [3] -> [7] : -5+i <= 0, cost: 1 16: [3] -> [4] : i'=1+i, -5+i > 0, cost: 1 13: [4] -> [2] : T, cost: 1 19: [7] -> [8] : i'=-1+i, 5+i < 0, cost: 1 20: [7] -> [8] : i'=0, 5+i >= 0, cost: 1 12: [8] -> [4] : T, cost: 1 Eliminating location [5] by chaining: Applied chaining First rule: [3] -> [5] : -5+i > 0, cost: 1 Second rule: [5] -> [6] : i'=1+i, T, cost: 1 New rule: [3] -> [6] : i'=1+i, -5+i > 0, cost: 1 Applied deletion Removed the following rules: 2 3 Eliminating location [6] by chaining: Applied chaining First rule: [3] -> [6] : i'=1+i, -5+i > 0, cost: 1 Second rule: [6] -> [4] : T, cost: 1 New rule: [3] -> [4] : i'=1+i, -5+i > 0, cost: 1 Applied deletion Removed the following rules: 4 15 Eliminating location [9] by chaining: Applied chaining First rule: [7] -> [9] : 5+i < 0, cost: 1 Second rule: [9] -> [10] : i'=-1+i, T, cost: 1 New rule: [7] -> [10] : i'=-1+i, 5+i < 0, cost: 1 Applied deletion Removed the following rules: 6 7 Eliminating location [11] by chaining: Applied chaining First rule: [7] -> [11] : 5+i >= 0, cost: 1 Second rule: [11] -> [12] : i'=0, T, cost: 1 New rule: [7] -> [12] : i'=0, 5+i >= 0, cost: 1 Applied deletion Removed the following rules: 9 10 Eliminating location [10] by chaining: Applied chaining First rule: [7] -> [10] : i'=-1+i, 5+i < 0, cost: 1 Second rule: [10] -> [8] : T, cost: 1 New rule: [7] -> [8] : i'=-1+i, 5+i < 0, cost: 1 Applied deletion Removed the following rules: 8 17 Eliminating location [12] by chaining: Applied chaining First rule: [7] -> [12] : i'=0, 5+i >= 0, cost: 1 Second rule: [12] -> [8] : T, cost: 1 New rule: [7] -> [8] : i'=0, 5+i >= 0, cost: 1 Applied deletion Removed the following rules: 11 18 Step with 0 Trace 0[T] Blocked [{}, {}] Step with 14 Trace 0[T], 14[(i <= 0 /\ i >= 0)] Blocked [{}, {}, {}] Backtrack Trace 0[T] Blocked [{}, {14[T]}] Step with 1 Trace 0[T], 1[(i > 0)] Blocked [{}, {14[T]}, {}] Step with 5 Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)] Blocked [{}, {14[T]}, {}, {}] Step with 20 Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)] Blocked [{}, {14[T]}, {}, {19[T]}, {}] Step with 12 Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)], 12[T] Blocked [{}, {14[T]}, {}, {19[T]}, {}, {}] Step with 13 Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)], 12[T], 13[T] Blocked [{}, {14[T]}, {}, {19[T]}, {}, {}, {}] Acceleration Failed marked recursive suffix as redundant Step with 14 Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)], 12[T], 13[T], 14[(i <= 0 /\ i >= 0)] Blocked [{}, {14[T]}, {}, {19[T]}, {}, {}, {1[T]}, {}] Backtrack Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)], 12[T], 13[T] Blocked [{}, {14[T]}, {}, {19[T]}, {}, {}, {1[T], 14[T]}] Backtrack Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)], 12[T] Blocked [{}, {14[T]}, {}, {19[T]}, {}, {13[T]}] Backtrack Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)], 20[(5+i >= 0)] Blocked [{}, {14[T]}, {}, {19[T]}, {12[T]}] Backtrack Trace 0[T], 1[(i > 0)], 5[(-5+i <= 0)] Blocked [{}, {14[T]}, {}, {19[T], 20[T]}] Backtrack Trace 0[T], 1[(i > 0)] Blocked [{}, {14[T]}, {5[T]}] Step with 16 Trace 0[T], 1[(i > 0)], 16[(-5+i > 0)] Blocked [{}, {14[T]}, {5[T]}, {}] Step with 13 Trace 0[T], 1[(i > 0)], 16[(-5+i > 0)], 13[T] Blocked [{}, {14[T]}, {5[T]}, {}, {}] Nonterm Start location: [1] Program variables: i 0: [1] -> [2] : i'=nondet, T, cost: 1 1: [2] -> [3] : (i < 0 \/ i > 0), cost: 1 14: [2] -> [13] : (i <= 0 /\ i >= 0), cost: 1 21: [2] -> LoAT_sink : (-1+n >= 0 /\ -5+i > 0 /\ i > 0), cost: NONTERM 22: [2] -> [2] : i'=n+i, (-1+n >= 0 /\ -5+i > 0 /\ i > 0), cost: 1 5: [3] -> [7] : -5+i <= 0, cost: 1 16: [3] -> [4] : i'=1+i, -5+i > 0, cost: 1 13: [4] -> [2] : T, cost: 1 19: [7] -> [8] : i'=-1+i, 5+i < 0, cost: 1 20: [7] -> [8] : i'=0, 5+i >= 0, cost: 1 12: [8] -> [4] : T, cost: 1 Certificate of Non-Termination Original rule: [2] -> [2] : i'=1+i, (-5+i > 0 /\ i > 0), cost: 1 New rule: [2] -> LoAT_sink : (-1+n >= 0 /\ -5+i > 0 /\ i > 0), cost: NONTERM -5+i > 0 [0]: monotonic increase yields -5+i > 0 i > 0 [0]: monotonic increase yields i > 0, dependencies: -5+i > 0 Replacement map: {-5+i > 0 -> -5+i > 0, i > 0 -> i > 0} Loop Acceleration Original rule: [2] -> [2] : i'=1+i, (-5+i > 0 /\ i > 0), cost: 1 New rule: [2] -> [2] : i'=n+i, (-1+n >= 0 /\ -5+i > 0 /\ i > 0), cost: 1 -5+i > 0 [0]: monotonic increase yields -5+i > 0 i > 0 [0]: monotonic increase yields i > 0, dependencies: -5+i > 0 Replacement map: {-5+i > 0 -> -5+i > 0, i > 0 -> i > 0} Step with 21 Trace 0[T], 21[(-1+n >= 0 /\ -5+i > 0 /\ i > 0)] Blocked [{}, {14[T]}, {21[T]}] Refute Counterexample [ i=6 ] 0 [ i=i ] 21 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b