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