NO Initial ITS Start location: [1] Program variables: x y 0: [1] -> [2] : x'=nondet, T, cost: 1 1: [2] -> [3] : y'=nondet1, T, cost: 1 2: [3] -> [4] : (y > 0 /\ x > 0), cost: 1 5: [3] -> [6] : (y <= 0 \/ x <= 0), cost: 1 3: [4] -> [5] : x'=10*y-2*x, T, cost: 1 4: [5] -> [3] : T, cost: 1 Chained Linear Paths Start location: [1] Program variables: x y 6: [1] -> [3] : x'=nondet, y'=nondet1, T, cost: 1 5: [3] -> [6] : (y <= 0 \/ x <= 0), cost: 1 8: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 Eliminating location [2] by chaining: Applied chaining First rule: [1] -> [2] : x'=nondet, T, cost: 1 Second rule: [2] -> [3] : y'=nondet1, T, cost: 1 New rule: [1] -> [3] : x'=nondet, y'=nondet1, T, cost: 1 Applied deletion Removed the following rules: 0 1 Eliminating location [4] by chaining: Applied chaining First rule: [3] -> [4] : (y > 0 /\ x > 0), cost: 1 Second rule: [4] -> [5] : x'=10*y-2*x, T, cost: 1 New rule: [3] -> [5] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 Applied deletion Removed the following rules: 2 3 Eliminating location [5] by chaining: Applied chaining First rule: [3] -> [5] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 Second rule: [5] -> [3] : T, cost: 1 New rule: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 Applied deletion Removed the following rules: 4 7 Unrolled Loops Start location: [1] Program variables: x y 6: [1] -> [3] : x'=nondet, y'=nondet1, T, cost: 1 5: [3] -> [6] : (y <= 0 \/ x <= 0), cost: 1 8: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 9: [3] -> [3] : x'=-10*y+4*x, (10*y-2*x > 0 /\ y > 0 /\ x > 0), cost: 1 Unrolling Original rule: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 New rule: [3] -> [3] : x'=-10*y+4*x, (10*y-2*x > 0 /\ y > 0 /\ x > 0), cost: 1 Step with 6 Trace 6[T] Blocked [{}, {}] Step with 5 Trace 6[T], 5[(y <= 0)] Blocked [{}, {}, {}] Backtrack Trace 6[T] Blocked [{}, {5[y <= 0]}] Step with 5 Trace 6[T], 5[(x <= 0)] Blocked [{}, {5[y <= 0]}, {}] Backtrack Trace 6[T] Blocked [{}, {5[(y <= 0 /\ x <= 0)]}] Step with 8 Trace 6[T], 8[(y > 0 /\ x > 0)] Blocked [{}, {5[T]}, {}] Nonterm Start location: [1] Program variables: x y 6: [1] -> [3] : x'=nondet, y'=nondet1, T, cost: 1 5: [3] -> [6] : (y <= 0 \/ x <= 0), cost: 1 8: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 9: [3] -> [3] : x'=-10*y+4*x, (10*y-2*x > 0 /\ y > 0 /\ x > 0), cost: 1 10: [3] -> LoAT_sink : (10*y-2*x > 0 /\ 10*y-3*x <= 0 /\ -20*y+6*x <= 0 /\ y > 0 /\ x > 0), cost: NONTERM unrolling Original rule: [3] -> [3] : x'=10*y-2*x, (y > 0 /\ x > 0), cost: 1 New rule: [3] -> [3] : x'=-10*y+4*x, (10*y-2*x > 0 /\ y > 0 /\ x > 0), cost: 1 Certificate of Non-Termination Original rule: [3] -> [3] : x'=-10*y+4*x, (10*y-2*x > 0 /\ y > 0 /\ x > 0), cost: 1 New rule: [3] -> LoAT_sink : (10*y-2*x > 0 /\ 10*y-3*x <= 0 /\ -20*y+6*x <= 0 /\ y > 0 /\ x > 0), cost: NONTERM 10*y-2*x > 0 [0]: montonic decrease yields -2*4^(-1+n)*x+10/3*y+20/3*y*4^(-1+n) > 0, dependencies: y > 0 10*y-2*x > 0 [1]: eventual decrease yields (10*y-2*x > 0 /\ -2*4^(-1+n)*x+10/3*y+20/3*y*4^(-1+n) > 0) 10*y-2*x > 0 [2]: eventual increase yields (10*y-2*x > 0 /\ -20*y+6*x <= 0) y > 0 [0]: monotonic increase yields y > 0 x > 0 [0]: montonic decrease yields 4^(-1+n)*x+10/3*y-10/3*y*4^(-1+n) > 0, dependencies: 10*y-2*x > 0 x > 0 [1]: eventual increase yields (10*y-3*x <= 0 /\ x > 0) Replacement map: {10*y-2*x > 0 -> (10*y-2*x > 0 /\ -20*y+6*x <= 0), y > 0 -> y > 0, x > 0 -> (10*y-3*x <= 0 /\ x > 0)} Step with 10 Trace 6[T], 10[(10*y-2*x > 0 /\ 10*y-3*x <= 0 /\ -20*y+6*x <= 0 /\ y > 0 /\ x > 0)] Blocked [{}, {5[T]}, {10[T]}] Refute Counterexample [ x=10 y=3 ] 6 [ x=x y=y ] 10 NO Build SHA: a05f16bf13df659c382799650051f91bf6828c7b