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