NO Initial ITS Start location: l5 Program variables: __disjvr_0^0 x^0 y^0 0: l0 -> l1 : __disjvr_0^0'=__disjvr_0^post1, x^0'=x^post1, y^0'=y^post1, (-x^post1+x^0 == 0 /\ -y^post1+y^0 == 0 /\ __disjvr_0^0-__disjvr_0^post1 == 0), cost: 1 1: l1 -> l3 : __disjvr_0^0'=__disjvr_0^post2, x^0'=x^post2, y^0'=y^post2, (__disjvr_0^0-__disjvr_0^post2 == 0 /\ -y^post2+y^0 == 0 /\ 1-x^0 <= 0 /\ -x^post2+x^0 == 0), cost: 1 2: l3 -> l4 : __disjvr_0^0'=__disjvr_0^post3, x^0'=x^post3, y^0'=y^post3, (-__disjvr_0^0+__disjvr_0^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post3 == 0 /\ -y^post3+y^0 == 0 /\ -x^post3+x^0 == 0), cost: 1 3: l4 -> l2 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (-y^post4+y^0 == 0 /\ x^post4-x^0-y^0 == 0 /\ __disjvr_0^0-__disjvr_0^post4 == 0), cost: 1 4: l2 -> l1 : __disjvr_0^0'=__disjvr_0^post5, x^0'=x^post5, y^0'=y^post5, (x^0-x^post5 == 0 /\ -y^post5+y^0 == 0 /\ -__disjvr_0^post5+__disjvr_0^0 == 0), cost: 1 5: l5 -> l0 : __disjvr_0^0'=__disjvr_0^post6, x^0'=x^post6, y^0'=y^post6, (-__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ x^0-x^post6 == 0), cost: 1 Chained Linear Paths Start location: l5 Program variables: __disjvr_0^0 x^0 y^0 9: l1 -> l1 : __disjvr_0^0'=__disjvr_0^post5, x^0'=x^post5, y^0'=y^post5, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post5+y^post4 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ x^post4-x^post5 == 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ -__disjvr_0^post5+__disjvr_0^post4 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 6: l5 -> l1 : __disjvr_0^0'=__disjvr_0^post1, x^0'=x^post1, y^0'=y^post1, (-__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ y^post6-y^post1 == 0 /\ -x^post1+x^post6 == 0 /\ x^0-x^post6 == 0 /\ __disjvr_0^post6-__disjvr_0^post1 == 0), cost: 1 Eliminating location l0 by chaining: Applied chaining First rule: l5 -> l0 : __disjvr_0^0'=__disjvr_0^post6, x^0'=x^post6, y^0'=y^post6, (-__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ x^0-x^post6 == 0), cost: 1 Second rule: l0 -> l1 : __disjvr_0^0'=__disjvr_0^post1, x^0'=x^post1, y^0'=y^post1, (-x^post1+x^0 == 0 /\ -y^post1+y^0 == 0 /\ __disjvr_0^0-__disjvr_0^post1 == 0), cost: 1 New rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^post1, x^0'=x^post1, y^0'=y^post1, (-__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ y^post6-y^post1 == 0 /\ -x^post1+x^post6 == 0 /\ x^0-x^post6 == 0 /\ __disjvr_0^post6-__disjvr_0^post1 == 0), cost: 1 Applied deletion Removed the following rules: 0 5 Eliminating location l3 by chaining: Applied chaining First rule: l1 -> l3 : __disjvr_0^0'=__disjvr_0^post2, x^0'=x^post2, y^0'=y^post2, (__disjvr_0^0-__disjvr_0^post2 == 0 /\ -y^post2+y^0 == 0 /\ 1-x^0 <= 0 /\ -x^post2+x^0 == 0), cost: 1 Second rule: l3 -> l4 : __disjvr_0^0'=__disjvr_0^post3, x^0'=x^post3, y^0'=y^post3, (-__disjvr_0^0+__disjvr_0^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post3 == 0 /\ -y^post3+y^0 == 0 /\ -x^post3+x^0 == 0), cost: 1 New rule: l1 -> l4 : __disjvr_0^0'=__disjvr_0^post3, x^0'=x^post3, y^0'=y^post3, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -y^post2+y^0 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 Applied deletion Removed the following rules: 1 2 Eliminating location l4 by chaining: Applied chaining First rule: l1 -> l4 : __disjvr_0^0'=__disjvr_0^post3, x^0'=x^post3, y^0'=y^post3, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -y^post2+y^0 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 Second rule: l4 -> l2 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (-y^post4+y^0 == 0 /\ x^post4-x^0-y^0 == 0 /\ __disjvr_0^0-__disjvr_0^post4 == 0), cost: 1 New rule: l1 -> l2 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 Applied deletion Removed the following rules: 3 7 Eliminating location l2 by chaining: Applied chaining First rule: l1 -> l2 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 Second rule: l2 -> l1 : __disjvr_0^0'=__disjvr_0^post5, x^0'=x^post5, y^0'=y^post5, (x^0-x^post5 == 0 /\ -y^post5+y^0 == 0 /\ -__disjvr_0^post5+__disjvr_0^0 == 0), cost: 1 New rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^post5, x^0'=x^post5, y^0'=y^post5, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post5+y^post4 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ x^post4-x^post5 == 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ -__disjvr_0^post5+__disjvr_0^post4 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 Applied deletion Removed the following rules: 4 8 Simplified Transitions Start location: l5 Program variables: x^0 y^0 11: l1 -> l1 : x^0'=x^0+y^0, 1-x^0 <= 0, cost: 1 10: l5 -> l1 : T, cost: 1 Propagated Equalities Original rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^post1, x^0'=x^post1, y^0'=y^post1, (-__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ y^post6-y^post1 == 0 /\ -x^post1+x^post6 == 0 /\ x^0-x^post6 == 0 /\ __disjvr_0^post6-__disjvr_0^post1 == 0), cost: 1 New rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^post6, x^0'=x^post6, y^0'=y^post6, (0 == 0 /\ -__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ x^0-x^post6 == 0), cost: 1 propagated equality y^post1 = y^post6 propagated equality x^post1 = x^post6 propagated equality __disjvr_0^post1 = __disjvr_0^post6 Propagated Equalities Original rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^post6, x^0'=x^post6, y^0'=y^post6, (0 == 0 /\ -__disjvr_0^post6+__disjvr_0^0 == 0 /\ -y^post6+y^0 == 0 /\ x^0-x^post6 == 0), cost: 1 New rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0, y^0'=y^0, 0 == 0, cost: 1 propagated equality __disjvr_0^post6 = __disjvr_0^0 propagated equality y^post6 = y^0 propagated equality x^post6 = x^0 Simplified Guard Original rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0, y^0'=y^0, 0 == 0, cost: 1 New rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0, y^0'=y^0, T, cost: 1 Removed Trivial Updates Original rule: l5 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0, y^0'=y^0, T, cost: 1 New rule: l5 -> l1 : T, cost: 1 Propagated Equalities Original rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^post5, x^0'=x^post5, y^0'=y^post5, (x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post5+y^post4 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ x^post4-x^post5 == 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ -__disjvr_0^post5+__disjvr_0^post4 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 New rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (0 == 0 /\ x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 propagated equality y^post5 = y^post4 propagated equality x^post5 = x^post4 propagated equality __disjvr_0^post5 = __disjvr_0^post4 Propagated Equalities Original rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^post4, x^0'=x^post4, y^0'=y^post4, (0 == 0 /\ x^post2-x^post3 == 0 /\ y^post2-y^post3 == 0 /\ __disjvr_0^0-__disjvr_0^post2 == 0 /\ -__disjvr_0^post4+__disjvr_0^post3 == 0 /\ -y^post2+y^0 == 0 /\ -y^post4+y^post3 == 0 /\ 1-x^0 <= 0 /\ -__disjvr_0^post2+__disjvr_0^post3 == 0 /\ x^post4-x^post3-y^post3 == 0 /\ __disjvr_0^post2-__disjvr_0^post3 == 0 /\ -x^post2+x^0 == 0), cost: 1 New rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0+y^0, y^0'=y^0, (0 == 0 /\ 1-x^0 <= 0), cost: 1 propagated equality x^post2 = x^post3 propagated equality y^post2 = y^post3 propagated equality __disjvr_0^post2 = __disjvr_0^0 propagated equality __disjvr_0^post3 = __disjvr_0^post4 propagated equality y^post3 = y^0 propagated equality y^post4 = y^0 propagated equality __disjvr_0^post4 = __disjvr_0^0 propagated equality x^post3 = x^post4-y^0 propagated equality x^post4 = x^0+y^0 Simplified Guard Original rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0+y^0, y^0'=y^0, (0 == 0 /\ 1-x^0 <= 0), cost: 1 New rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0+y^0, y^0'=y^0, 1-x^0 <= 0, cost: 1 Removed Trivial Updates Original rule: l1 -> l1 : __disjvr_0^0'=__disjvr_0^0, x^0'=x^0+y^0, y^0'=y^0, 1-x^0 <= 0, cost: 1 New rule: l1 -> l1 : x^0'=x^0+y^0, 1-x^0 <= 0, cost: 1 Step with 10 Trace 10[T] Blocked [{}, {}] Step with 11 Trace 10[T], 11[(1-x^0 <= 0)] Blocked [{}, {}, {}] Nonterm Start location: l5 Program variables: x^0 y^0 11: l1 -> l1 : x^0'=x^0+y^0, 1-x^0 <= 0, cost: 1 12: l1 -> LoAT_sink : (-1+x^0 >= 0 /\ -y^0 <= 0), cost: NONTERM 13: l1 -> l1 : x^0'=x^0+n*y^0, (-1+x^0+(-1+n)*y^0 >= 0 /\ -1+n >= 0 /\ -1+x^0 >= 0), cost: 1 10: l5 -> l1 : T, cost: 1 Certificate of Non-Termination Original rule: l1 -> l1 : x^0'=x^0+y^0, (1-x^0 <= 0), cost: 1 New rule: l1 -> LoAT_sink : (-1+x^0 >= 0 /\ -y^0 <= 0), cost: NONTERM -1+x^0 >= 0 [0]: eventual decrease yields (-1+x^0+(-1+n)*y^0 >= 0 /\ -1+x^0 >= 0) -1+x^0 >= 0 [1]: eventual increase yields (-1+x^0 >= 0 /\ -y^0 <= 0) Replacement map: {-1+x^0 >= 0 -> (-1+x^0 >= 0 /\ -y^0 <= 0)} Loop Acceleration Original rule: l1 -> l1 : x^0'=x^0+y^0, (1-x^0 <= 0), cost: 1 New rule: l1 -> l1 : x^0'=x^0+n*y^0, (-1+x^0+(-1+n)*y^0 >= 0 /\ -1+n >= 0 /\ -1+x^0 >= 0), cost: 1 -1+x^0 >= 0 [0]: eventual decrease yields (-1+x^0+(-1+n)*y^0 >= 0 /\ -1+x^0 >= 0) -1+x^0 >= 0 [1]: eventual increase yields (-1+x^0 >= 0 /\ -y^0 <= 0) Replacement map: {-1+x^0 >= 0 -> (-1+x^0+(-1+n)*y^0 >= 0 /\ -1+x^0 >= 0)} Step with 12 Trace 10[T], 12[(-1+x^0 >= 0 /\ -y^0 <= 0)] Blocked [{}, {}, {12[T]}] Refute Counterexample [ x^0=1 y^0=0 ] 10 [ x^0=1 y^0=0 ] 12 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b