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