NO Initial ITS Start location: l3 Program variables: __const_1000^0 x^0 0: l0 -> l1 : __const_1000^0'=__const_1000^post1, x^0'=x^post1, (1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 1: l1 -> l0 : __const_1000^0'=__const_1000^post2, x^0'=x^post2, (-x^post2+x^0 == 0 /\ -__const_1000^post2+__const_1000^0 == 0), cost: 1 2: l2 -> l0 : __const_1000^0'=__const_1000^post3, x^0'=x^post3, (-__const_1000^post3+__const_1000^0 == 0 /\ x^0-x^post3 == 0), cost: 1 3: l3 -> l2 : __const_1000^0'=__const_1000^post4, x^0'=x^post4, (x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0), cost: 1 Chained Linear Paths Start location: l3 Program variables: __const_1000^0 x^0 5: l0 -> l0 : __const_1000^0'=__const_1000^post2, x^0'=x^post2, (1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ __const_1000^post1-__const_1000^post2 == 0 /\ -x^post2+x^post1 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 4: l3 -> l0 : __const_1000^0'=__const_1000^post3, x^0'=x^post3, (x^post4-x^post3 == 0 /\ x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0 /\ __const_1000^post4-__const_1000^post3 == 0), cost: 1 Eliminating location l2 by chaining: Applied chaining First rule: l3 -> l2 : __const_1000^0'=__const_1000^post4, x^0'=x^post4, (x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0), cost: 1 Second rule: l2 -> l0 : __const_1000^0'=__const_1000^post3, x^0'=x^post3, (-__const_1000^post3+__const_1000^0 == 0 /\ x^0-x^post3 == 0), cost: 1 New rule: l3 -> l0 : __const_1000^0'=__const_1000^post3, x^0'=x^post3, (x^post4-x^post3 == 0 /\ x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0 /\ __const_1000^post4-__const_1000^post3 == 0), cost: 1 Applied deletion Removed the following rules: 2 3 Eliminating location l1 by chaining: Applied chaining First rule: l0 -> l1 : __const_1000^0'=__const_1000^post1, x^0'=x^post1, (1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 Second rule: l1 -> l0 : __const_1000^0'=__const_1000^post2, x^0'=x^post2, (-x^post2+x^0 == 0 /\ -__const_1000^post2+__const_1000^0 == 0), cost: 1 New rule: l0 -> l0 : __const_1000^0'=__const_1000^post2, x^0'=x^post2, (1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ __const_1000^post1-__const_1000^post2 == 0 /\ -x^post2+x^post1 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 Applied deletion Removed the following rules: 0 1 Simplified Transitions Start location: l3 Program variables: __const_1000^0 x^0 7: l0 -> l0 : x^0'=x^0-__const_1000^0, 1-x^0+__const_1000^0 <= 0, cost: 1 6: l3 -> l0 : T, cost: 1 Propagated Equalities Original rule: l3 -> l0 : __const_1000^0'=__const_1000^post3, x^0'=x^post3, (x^post4-x^post3 == 0 /\ x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0 /\ __const_1000^post4-__const_1000^post3 == 0), cost: 1 New rule: l3 -> l0 : __const_1000^0'=__const_1000^post4, x^0'=x^post4, (0 == 0 /\ x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0), cost: 1 propagated equality x^post3 = x^post4 propagated equality __const_1000^post3 = __const_1000^post4 Propagated Equalities Original rule: l3 -> l0 : __const_1000^0'=__const_1000^post4, x^0'=x^post4, (0 == 0 /\ x^0-x^post4 == 0 /\ -__const_1000^post4+__const_1000^0 == 0), cost: 1 New rule: l3 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0, 0 == 0, cost: 1 propagated equality x^post4 = x^0 propagated equality __const_1000^post4 = __const_1000^0 Simplified Guard Original rule: l3 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0, 0 == 0, cost: 1 New rule: l3 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0, T, cost: 1 Removed Trivial Updates Original rule: l3 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0, T, cost: 1 New rule: l3 -> l0 : T, cost: 1 Propagated Equalities Original rule: l0 -> l0 : __const_1000^0'=__const_1000^post2, x^0'=x^post2, (1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ __const_1000^post1-__const_1000^post2 == 0 /\ -x^post2+x^post1 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 New rule: l0 -> l0 : __const_1000^0'=__const_1000^post1, x^0'=x^post1, (0 == 0 /\ 1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 propagated equality __const_1000^post2 = __const_1000^post1 propagated equality x^post2 = x^post1 Propagated Equalities Original rule: l0 -> l0 : __const_1000^0'=__const_1000^post1, x^0'=x^post1, (0 == 0 /\ 1-x^post1 <= 0 /\ -__const_1000^post1+__const_1000^0 == 0 /\ -x^0+x^post1+__const_1000^0 == 0), cost: 1 New rule: l0 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0-__const_1000^0, (0 == 0 /\ 1-x^0+__const_1000^0 <= 0), cost: 1 propagated equality __const_1000^post1 = __const_1000^0 propagated equality x^post1 = x^0-__const_1000^0 Simplified Guard Original rule: l0 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0-__const_1000^0, (0 == 0 /\ 1-x^0+__const_1000^0 <= 0), cost: 1 New rule: l0 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0-__const_1000^0, 1-x^0+__const_1000^0 <= 0, cost: 1 Removed Trivial Updates Original rule: l0 -> l0 : __const_1000^0'=__const_1000^0, x^0'=x^0-__const_1000^0, 1-x^0+__const_1000^0 <= 0, cost: 1 New rule: l0 -> l0 : x^0'=x^0-__const_1000^0, 1-x^0+__const_1000^0 <= 0, cost: 1 Step with 6 Trace 6[T] Blocked [{}, {}] Step with 7 Trace 6[T], 7[(1-x^0+__const_1000^0 <= 0)] Blocked [{}, {}, {}] Nonterm Start location: l3 Program variables: __const_1000^0 x^0 7: l0 -> l0 : x^0'=x^0-__const_1000^0, 1-x^0+__const_1000^0 <= 0, cost: 1 8: l0 -> LoAT_sink : (-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0), cost: NONTERM 9: l0 -> l0 : x^0'=x^0-n*__const_1000^0, (-1+x^0-__const_1000^0 >= 0 /\ -1-(-1+n)*__const_1000^0+x^0-__const_1000^0 >= 0 /\ -1+n >= 0), cost: 1 6: l3 -> l0 : T, cost: 1 Certificate of Non-Termination Original rule: l0 -> l0 : x^0'=x^0-__const_1000^0, (1-x^0+__const_1000^0 <= 0), cost: 1 New rule: l0 -> LoAT_sink : (-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0), cost: NONTERM -1+x^0-__const_1000^0 >= 0 [0]: eventual decrease yields (-1+x^0-__const_1000^0 >= 0 /\ -1-(-1+n)*__const_1000^0+x^0-__const_1000^0 >= 0) -1+x^0-__const_1000^0 >= 0 [1]: eventual increase yields (-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0) Replacement map: {-1+x^0-__const_1000^0 >= 0 -> (-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0)} Loop Acceleration Original rule: l0 -> l0 : x^0'=x^0-__const_1000^0, (1-x^0+__const_1000^0 <= 0), cost: 1 New rule: l0 -> l0 : x^0'=x^0-n*__const_1000^0, (-1+x^0-__const_1000^0 >= 0 /\ -1-(-1+n)*__const_1000^0+x^0-__const_1000^0 >= 0 /\ -1+n >= 0), cost: 1 -1+x^0-__const_1000^0 >= 0 [0]: eventual decrease yields (-1+x^0-__const_1000^0 >= 0 /\ -1-(-1+n)*__const_1000^0+x^0-__const_1000^0 >= 0) -1+x^0-__const_1000^0 >= 0 [1]: eventual increase yields (-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0) Replacement map: {-1+x^0-__const_1000^0 >= 0 -> (-1+x^0-__const_1000^0 >= 0 /\ -1-(-1+n)*__const_1000^0+x^0-__const_1000^0 >= 0)} Step with 8 Trace 6[T], 8[(-1+x^0-__const_1000^0 >= 0 /\ __const_1000^0 <= 0)] Blocked [{}, {}, {8[T]}] Refute Counterexample [ __const_1000^0=-1 x^0=0 ] 6 [ __const_1000^0=-1 x^0=0 ] 8 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b