NO Initial ITS Start location: l4 Program variables: pre_v^0 v^0 v_next^0 0: l0 -> l1 : pre_v^0'=pre_v^post1, v^0'=v^post1, v_next^0'=v_next^post1, (-v_next^post1+v_next^0 == 0 /\ 1+v^0-v_next^0 <= 0 /\ -v^post1+v^0 == 0 /\ pre_v^0-pre_v^post1 == 0), cost: 1 1: l0 -> l2 : pre_v^0'=pre_v^post2, v^0'=v^post2, v_next^0'=v_next^post2, (-v^post2+v^0 == 0 /\ -v_next^post2+v_next^0 == 0 /\ pre_v^0-pre_v^post2 == 0), cost: 1 2: l2 -> l0 : pre_v^0'=pre_v^post3, v^0'=v^post3, v_next^0'=v_next^post3, (0 == 0 /\ -v_next^post3+v^1 == 0 /\ pre_v^post3-v^0 == 0 /\ -1+v^post3-v^1 == 0), cost: 1 3: l3 -> l2 : pre_v^0'=pre_v^post4, v^0'=v^post4, v_next^0'=v_next^post4, (-v^post4+v^0 == 0 /\ -v_next^post4+v_next^0 == 0 /\ -pre_v^post4+pre_v^0 == 0), cost: 1 4: l4 -> l3 : pre_v^0'=pre_v^post5, v^0'=v^post5, v_next^0'=v_next^post5, (-v^post5+v^0 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0), cost: 1 Chained Linear Paths Start location: l4 Program variables: pre_v^0 v^0 v_next^0 0: l0 -> l1 : pre_v^0'=pre_v^post1, v^0'=v^post1, v_next^0'=v_next^post1, (-v_next^post1+v_next^0 == 0 /\ 1+v^0-v_next^0 <= 0 /\ -v^post1+v^0 == 0 /\ pre_v^0-pre_v^post1 == 0), cost: 1 1: l0 -> l2 : pre_v^0'=pre_v^post2, v^0'=v^post2, v_next^0'=v_next^post2, (-v^post2+v^0 == 0 /\ -v_next^post2+v_next^0 == 0 /\ pre_v^0-pre_v^post2 == 0), cost: 1 2: l2 -> l0 : pre_v^0'=pre_v^post3, v^0'=v^post3, v_next^0'=v_next^post3, (0 == 0 /\ -v_next^post3+v^1 == 0 /\ pre_v^post3-v^0 == 0 /\ -1+v^post3-v^1 == 0), cost: 1 5: l4 -> l2 : pre_v^0'=pre_v^post4, v^0'=v^post4, v_next^0'=v_next^post4, (-v^post5+v^0 == 0 /\ v_next^post5-v_next^post4 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0 /\ v^post5-v^post4 == 0 /\ -pre_v^post4+pre_v^post5 == 0), cost: 1 Eliminating location l3 by chaining: Applied chaining First rule: l4 -> l3 : pre_v^0'=pre_v^post5, v^0'=v^post5, v_next^0'=v_next^post5, (-v^post5+v^0 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0), cost: 1 Second rule: l3 -> l2 : pre_v^0'=pre_v^post4, v^0'=v^post4, v_next^0'=v_next^post4, (-v^post4+v^0 == 0 /\ -v_next^post4+v_next^0 == 0 /\ -pre_v^post4+pre_v^0 == 0), cost: 1 New rule: l4 -> l2 : pre_v^0'=pre_v^post4, v^0'=v^post4, v_next^0'=v_next^post4, (-v^post5+v^0 == 0 /\ v_next^post5-v_next^post4 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0 /\ v^post5-v^post4 == 0 /\ -pre_v^post4+pre_v^post5 == 0), cost: 1 Applied deletion Removed the following rules: 3 4 Simplified Transitions Start location: l4 Program variables: pre_v^0 v^0 v_next^0 6: l0 -> l1 : 1+v^0-v_next^0 <= 0, cost: 1 7: l0 -> l2 : T, cost: 1 8: l2 -> l0 : pre_v^0'=v^0, v^0'=1+v^1, v_next^0'=v^1, T, cost: 1 9: l4 -> l2 : T, cost: 1 Propagated Equalities Original rule: l0 -> l1 : pre_v^0'=pre_v^post1, v^0'=v^post1, v_next^0'=v_next^post1, (-v_next^post1+v_next^0 == 0 /\ 1+v^0-v_next^0 <= 0 /\ -v^post1+v^0 == 0 /\ pre_v^0-pre_v^post1 == 0), cost: 1 New rule: l0 -> l1 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, (0 == 0 /\ 1+v^0-v_next^0 <= 0), cost: 1 propagated equality v_next^post1 = v_next^0 propagated equality v^post1 = v^0 propagated equality pre_v^post1 = pre_v^0 Simplified Guard Original rule: l0 -> l1 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, (0 == 0 /\ 1+v^0-v_next^0 <= 0), cost: 1 New rule: l0 -> l1 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 1+v^0-v_next^0 <= 0, cost: 1 Removed Trivial Updates Original rule: l0 -> l1 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 1+v^0-v_next^0 <= 0, cost: 1 New rule: l0 -> l1 : 1+v^0-v_next^0 <= 0, cost: 1 Propagated Equalities Original rule: l0 -> l2 : pre_v^0'=pre_v^post2, v^0'=v^post2, v_next^0'=v_next^post2, (-v^post2+v^0 == 0 /\ -v_next^post2+v_next^0 == 0 /\ pre_v^0-pre_v^post2 == 0), cost: 1 New rule: l0 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 0 == 0, cost: 1 propagated equality v^post2 = v^0 propagated equality v_next^post2 = v_next^0 propagated equality pre_v^post2 = pre_v^0 Simplified Guard Original rule: l0 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 0 == 0, cost: 1 New rule: l0 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, T, cost: 1 Removed Trivial Updates Original rule: l0 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, T, cost: 1 New rule: l0 -> l2 : T, cost: 1 Propagated Equalities Original rule: l2 -> l0 : pre_v^0'=pre_v^post3, v^0'=v^post3, v_next^0'=v_next^post3, (0 == 0 /\ -v_next^post3+v^1 == 0 /\ pre_v^post3-v^0 == 0 /\ -1+v^post3-v^1 == 0), cost: 1 New rule: l2 -> l0 : pre_v^0'=v^0, v^0'=1+v^1, v_next^0'=v^1, 0 == 0, cost: 1 propagated equality v_next^post3 = v^1 propagated equality pre_v^post3 = v^0 propagated equality v^post3 = 1+v^1 Simplified Guard Original rule: l2 -> l0 : pre_v^0'=v^0, v^0'=1+v^1, v_next^0'=v^1, 0 == 0, cost: 1 New rule: l2 -> l0 : pre_v^0'=v^0, v^0'=1+v^1, v_next^0'=v^1, T, cost: 1 Propagated Equalities Original rule: l4 -> l2 : pre_v^0'=pre_v^post4, v^0'=v^post4, v_next^0'=v_next^post4, (-v^post5+v^0 == 0 /\ v_next^post5-v_next^post4 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0 /\ v^post5-v^post4 == 0 /\ -pre_v^post4+pre_v^post5 == 0), cost: 1 New rule: l4 -> l2 : pre_v^0'=pre_v^post5, v^0'=v^post5, v_next^0'=v_next^post5, (0 == 0 /\ -v^post5+v^0 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0), cost: 1 propagated equality v_next^post4 = v_next^post5 propagated equality v^post4 = v^post5 propagated equality pre_v^post4 = pre_v^post5 Propagated Equalities Original rule: l4 -> l2 : pre_v^0'=pre_v^post5, v^0'=v^post5, v_next^0'=v_next^post5, (0 == 0 /\ -v^post5+v^0 == 0 /\ -v_next^post5+v_next^0 == 0 /\ pre_v^0-pre_v^post5 == 0), cost: 1 New rule: l4 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 0 == 0, cost: 1 propagated equality v^post5 = v^0 propagated equality v_next^post5 = v_next^0 propagated equality pre_v^post5 = pre_v^0 Simplified Guard Original rule: l4 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, 0 == 0, cost: 1 New rule: l4 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, T, cost: 1 Removed Trivial Updates Original rule: l4 -> l2 : pre_v^0'=pre_v^0, v^0'=v^0, v_next^0'=v_next^0, T, cost: 1 New rule: l4 -> l2 : T, cost: 1 Step with 9 Trace 9[T] Blocked [{}, {}] Step with 8 Trace 9[T], 8[T] Blocked [{}, {}, {}] Step with 7 Trace 9[T], 8[T], 7[T] Blocked [{}, {}, {6[T]}, {}] Nonterm Start location: l4 Program variables: pre_v^0 v^0 v_next^0 6: l0 -> l1 : 1+v^0-v_next^0 <= 0, cost: 1 7: l0 -> l2 : T, cost: 1 8: l2 -> l0 : pre_v^0'=v^0, v^0'=1+v^1, v_next^0'=v^1, T, cost: 1 10: l2 -> LoAT_sink : -1+n >= 0, cost: NONTERM 11: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, T, cost: 1 9: l4 -> l2 : T, cost: 1 unrolling Original rule: l2 -> l2 : pre_v^0'=v^0, v^0'=1+v^11, v_next^0'=v^11, T, cost: 1 New rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, T, cost: 1 Certificate of Non-Termination Original rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, T, cost: 1 New rule: l2 -> LoAT_sink : -1+n >= 0, cost: NONTERM Replacement map: {} Loop Acceleration Original rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, T, cost: 1 New rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, -1+n >= 0, cost: 1 Replacement map: {} Eliminated Temporary Variables via Transitive Closure Original rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, -1+n >= 0, cost: 1 New rule: l2 -> l2 : pre_v^0'=1+v^11, v^0'=1+v^111, v_next^0'=v^111, T, cost: 1 Step with 10 Trace 9[T], 10[-1+n >= 0] Blocked [{}, {}, {10[T]}] Refute Counterexample [ pre_v^0=0 v^0=0 v_next^0=0 ] 9 [ pre_v^0=0 v^0=0 v_next^0=0 ] 10 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b