NO Initial ITS Start location: l4 Program variables: x^0 0: l0 -> l2 : x^0'=x^post1, 1+x^post1-x^0 == 0, cost: 1 1: l2 -> l1 : x^0'=x^post2, (-x^post2+x^0 == 0 /\ -299+x^0 <= 0), cost: 1 2: l2 -> l1 : x^0'=x^post3, (-x^post3+x^0 == 0 /\ 301-x^0 <= 0), cost: 1 3: l1 -> l0 : x^0'=x^post4, -x^post4+x^0 == 0, cost: 1 4: l3 -> l0 : x^0'=x^post5, -100+x^post5 == 0, cost: 1 5: l4 -> l3 : x^0'=x^post6, -x^post6+x^0 == 0, cost: 1 Chained Linear Paths Start location: l4 Program variables: x^0 0: l0 -> l2 : x^0'=x^post1, 1+x^post1-x^0 == 0, cost: 1 1: l2 -> l1 : x^0'=x^post2, (-x^post2+x^0 == 0 /\ -299+x^0 <= 0), cost: 1 2: l2 -> l1 : x^0'=x^post3, (-x^post3+x^0 == 0 /\ 301-x^0 <= 0), cost: 1 3: l1 -> l0 : x^0'=x^post4, -x^post4+x^0 == 0, cost: 1 6: l4 -> l0 : x^0'=x^post5, (-x^post6+x^0 == 0 /\ -100+x^post5 == 0), cost: 1 Eliminating location l3 by chaining: Applied chaining First rule: l4 -> l3 : x^0'=x^post6, -x^post6+x^0 == 0, cost: 1 Second rule: l3 -> l0 : x^0'=x^post5, -100+x^post5 == 0, cost: 1 New rule: l4 -> l0 : x^0'=x^post5, (-x^post6+x^0 == 0 /\ -100+x^post5 == 0), cost: 1 Applied deletion Removed the following rules: 4 5 Simplified Transitions Start location: l4 Program variables: x^0 7: l0 -> l2 : x^0'=-1+x^0, T, cost: 1 8: l2 -> l1 : -299+x^0 <= 0, cost: 1 9: l2 -> l1 : 301-x^0 <= 0, cost: 1 10: l1 -> l0 : T, cost: 1 11: l4 -> l0 : x^0'=100, T, cost: 1 Propagated Equalities Original rule: l0 -> l2 : x^0'=x^post1, 1+x^post1-x^0 == 0, cost: 1 New rule: l0 -> l2 : x^0'=-1+x^0, 0 == 0, cost: 1 propagated equality x^post1 = -1+x^0 Simplified Guard Original rule: l0 -> l2 : x^0'=-1+x^0, 0 == 0, cost: 1 New rule: l0 -> l2 : x^0'=-1+x^0, T, cost: 1 Propagated Equalities Original rule: l2 -> l1 : x^0'=x^post2, (-x^post2+x^0 == 0 /\ -299+x^0 <= 0), cost: 1 New rule: l2 -> l1 : x^0'=x^0, (0 == 0 /\ -299+x^0 <= 0), cost: 1 propagated equality x^post2 = x^0 Simplified Guard Original rule: l2 -> l1 : x^0'=x^0, (0 == 0 /\ -299+x^0 <= 0), cost: 1 New rule: l2 -> l1 : x^0'=x^0, -299+x^0 <= 0, cost: 1 Removed Trivial Updates Original rule: l2 -> l1 : x^0'=x^0, -299+x^0 <= 0, cost: 1 New rule: l2 -> l1 : -299+x^0 <= 0, cost: 1 Propagated Equalities Original rule: l2 -> l1 : x^0'=x^post3, (-x^post3+x^0 == 0 /\ 301-x^0 <= 0), cost: 1 New rule: l2 -> l1 : x^0'=x^0, (0 == 0 /\ 301-x^0 <= 0), cost: 1 propagated equality x^post3 = x^0 Simplified Guard Original rule: l2 -> l1 : x^0'=x^0, (0 == 0 /\ 301-x^0 <= 0), cost: 1 New rule: l2 -> l1 : x^0'=x^0, 301-x^0 <= 0, cost: 1 Removed Trivial Updates Original rule: l2 -> l1 : x^0'=x^0, 301-x^0 <= 0, cost: 1 New rule: l2 -> l1 : 301-x^0 <= 0, cost: 1 Propagated Equalities Original rule: l1 -> l0 : x^0'=x^post4, -x^post4+x^0 == 0, cost: 1 New rule: l1 -> l0 : x^0'=x^0, 0 == 0, cost: 1 propagated equality x^post4 = x^0 Simplified Guard Original rule: l1 -> l0 : x^0'=x^0, 0 == 0, cost: 1 New rule: l1 -> l0 : x^0'=x^0, T, cost: 1 Removed Trivial Updates Original rule: l1 -> l0 : x^0'=x^0, T, cost: 1 New rule: l1 -> l0 : T, cost: 1 Propagated Equalities Original rule: l4 -> l0 : x^0'=x^post5, (-x^post6+x^0 == 0 /\ -100+x^post5 == 0), cost: 1 New rule: l4 -> l0 : x^0'=100, (0 == 0 /\ -x^post6+x^0 == 0), cost: 1 propagated equality x^post5 = 100 Propagated Equalities Original rule: l4 -> l0 : x^0'=100, (0 == 0 /\ -x^post6+x^0 == 0), cost: 1 New rule: l4 -> l0 : x^0'=100, 0 == 0, cost: 1 propagated equality x^post6 = x^0 Simplified Guard Original rule: l4 -> l0 : x^0'=100, 0 == 0, cost: 1 New rule: l4 -> l0 : x^0'=100, T, cost: 1 Step with 11 Trace 11[T] Blocked [{}, {}] Step with 7 Trace 11[T], 7[T] Blocked [{}, {}, {}] Step with 8 Trace 11[T], 7[T], 8[(-299+x^0 <= 0)] Blocked [{}, {}, {}, {}] Step with 10 Trace 11[T], 7[T], 8[(-299+x^0 <= 0)], 10[T] Blocked [{}, {}, {}, {}, {}] Nonterm Start location: l4 Program variables: x^0 7: l0 -> l2 : x^0'=-1+x^0, T, cost: 1 12: l0 -> LoAT_sink : (300-x^0 >= 0 /\ -1+n >= 0), cost: NONTERM 13: l0 -> l0 : x^0'=-n+x^0, (300-x^0 >= 0 /\ -1+n >= 0), cost: 1 8: l2 -> l1 : -299+x^0 <= 0, cost: 1 9: l2 -> l1 : 301-x^0 <= 0, cost: 1 10: l1 -> l0 : T, cost: 1 11: l4 -> l0 : x^0'=100, T, cost: 1 Certificate of Non-Termination Original rule: l0 -> l0 : x^0'=-1+x^0, -300+x^0 <= 0, cost: 1 New rule: l0 -> LoAT_sink : (300-x^0 >= 0 /\ -1+n >= 0), cost: NONTERM 300-x^0 >= 0 [0]: monotonic increase yields 300-x^0 >= 0 Replacement map: {300-x^0 >= 0 -> 300-x^0 >= 0} Loop Acceleration Original rule: l0 -> l0 : x^0'=-1+x^0, -300+x^0 <= 0, cost: 1 New rule: l0 -> l0 : x^0'=-n+x^0, (300-x^0 >= 0 /\ -1+n >= 0), cost: 1 300-x^0 >= 0 [0]: monotonic increase yields 300-x^0 >= 0 Replacement map: {300-x^0 >= 0 -> 300-x^0 >= 0} Step with 12 Trace 11[T], 12[(300-x^0 >= 0 /\ -1+n >= 0)] Blocked [{}, {}, {12[T]}] Refute Counterexample [ x^0=100 ] 11 [ x^0=x^0 ] 12 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b