WORST_CASE(Omega(1),?) ### Pre-processing the ITS problem ### Initial linear ITS problem Start location: __init 0: f1 -> f2 : arg1'=arg1P_1, arg2'=arg2P_1, [ arg2==arg2P_1 ], cost: 1 1: f2 -> f3 : arg1'=arg1P_2, arg2'=arg2P_2, [ arg1==arg1P_2 ], cost: 1 7: f3 -> f4 : arg1'=arg1P_8, arg2'=arg2P_8, [ arg2+arg1<=0 && arg1==arg1P_8 && arg2==arg2P_8 ], cost: 1 8: f3 -> f5 : arg1'=arg1P_9, arg2'=arg2P_9, [ arg2+arg1>0 && arg1==arg1P_9 && arg2==arg2P_9 ], cost: 1 2: f7 -> f8 : arg1'=arg1P_3, arg2'=arg2P_3, [ arg1P_3==arg2+2*arg1 && arg2==arg2P_3 ], cost: 1 3: f8 -> f9 : arg1'=arg1P_4, arg2'=arg2P_4, [ arg2P_4==-1+arg2 && arg1==arg1P_4 ], cost: 1 5: f9 -> f4 : arg1'=arg1P_6, arg2'=arg2P_6, [ arg1==arg1P_6 && arg2==arg2P_6 ], cost: 1 4: f4 -> f7 : arg1'=arg1P_5, arg2'=arg2P_5, [ arg1>0 && arg1==arg1P_5 && arg2==arg2P_5 ], cost: 1 6: f4 -> f10 : arg1'=arg1P_7, arg2'=arg2P_7, [ arg1<=0 && arg1==arg1P_7 && arg2==arg2P_7 ], cost: 1 9: f10 -> f6 : arg1'=arg1P_10, arg2'=arg2P_10, [ arg1==arg1P_10 && arg2==arg2P_10 ], cost: 1 10: f5 -> f6 : arg1'=arg1P_11, arg2'=arg2P_11, [ arg1==arg1P_11 && arg2==arg2P_11 ], cost: 1 11: __init -> f1 : arg1'=arg1P_12, arg2'=arg2P_12, [], cost: 1 Checking for constant complexity: The following rule is satisfiable with cost >= 1, yielding constant complexity: 11: __init -> f1 : arg1'=arg1P_12, arg2'=arg2P_12, [], cost: 1 Removed unreachable and leaf rules: Start location: __init 0: f1 -> f2 : arg1'=arg1P_1, arg2'=arg2P_1, [ arg2==arg2P_1 ], cost: 1 1: f2 -> f3 : arg1'=arg1P_2, arg2'=arg2P_2, [ arg1==arg1P_2 ], cost: 1 7: f3 -> f4 : arg1'=arg1P_8, arg2'=arg2P_8, [ arg2+arg1<=0 && arg1==arg1P_8 && arg2==arg2P_8 ], cost: 1 2: f7 -> f8 : arg1'=arg1P_3, arg2'=arg2P_3, [ arg1P_3==arg2+2*arg1 && arg2==arg2P_3 ], cost: 1 3: f8 -> f9 : arg1'=arg1P_4, arg2'=arg2P_4, [ arg2P_4==-1+arg2 && arg1==arg1P_4 ], cost: 1 5: f9 -> f4 : arg1'=arg1P_6, arg2'=arg2P_6, [ arg1==arg1P_6 && arg2==arg2P_6 ], cost: 1 4: f4 -> f7 : arg1'=arg1P_5, arg2'=arg2P_5, [ arg1>0 && arg1==arg1P_5 && arg2==arg2P_5 ], cost: 1 11: __init -> f1 : arg1'=arg1P_12, arg2'=arg2P_12, [], cost: 1 Simplified all rules, resulting in: Start location: __init 0: f1 -> f2 : arg1'=arg1P_1, [], cost: 1 1: f2 -> f3 : arg2'=arg2P_2, [], cost: 1 7: f3 -> f4 : [ arg2+arg1<=0 ], cost: 1 2: f7 -> f8 : arg1'=arg2+2*arg1, [], cost: 1 3: f8 -> f9 : arg2'=-1+arg2, [], cost: 1 5: f9 -> f4 : [], cost: 1 4: f4 -> f7 : [ arg1>0 ], cost: 1 11: __init -> f1 : arg1'=arg1P_12, arg2'=arg2P_12, [], cost: 1 ### Simplification by acceleration and chaining ### Eliminated locations (on linear paths): Start location: __init 17: f4 -> f4 : arg1'=arg2+2*arg1, arg2'=-1+arg2, [ arg1>0 ], cost: 4 14: __init -> f4 : arg1'=arg1P_1, arg2'=arg2P_2, [ arg2P_2+arg1P_1<=0 ], cost: 4 Accelerating simple loops of location 6. Accelerating the following rules: 17: f4 -> f4 : arg1'=arg2+2*arg1, arg2'=-1+arg2, [ arg1>0 ], cost: 4 [test] deduced invariant arg2+arg1<=0 Accelerated rule 17 with backward acceleration, yielding the new rule 18. [accelerate] Nesting with 1 inner and 1 outer candidates Accelerated all simple loops using metering functions (where possible): Start location: __init 17: f4 -> f4 : arg1'=arg2+2*arg1, arg2'=-1+arg2, [ arg1>0 ], cost: 4 18: f4 -> f4 : arg1'=1-arg2+2^k*arg1+k+arg2*2^k-2^k, arg2'=arg2-k, [ arg2+arg1<=0 && k>=0 && -2^(-1+k)-arg2+2^(-1+k)*arg1+k+2^(-1+k)*arg2>0 ], cost: 4*k 14: __init -> f4 : arg1'=arg1P_1, arg2'=arg2P_2, [ arg2P_2+arg1P_1<=0 ], cost: 4 Chained accelerated rules (with incoming rules): Start location: __init 14: __init -> f4 : arg1'=arg1P_1, arg2'=arg2P_2, [ arg2P_2+arg1P_1<=0 ], cost: 4 19: __init -> f4 : arg1'=arg2P_2+2*arg1P_1, arg2'=-1+arg2P_2, [ arg2P_2+arg1P_1<=0 && arg1P_1>0 ], cost: 8 20: __init -> f4 : arg1'=1+arg2P_2*2^k-arg2P_2+k-2^k+arg1P_1*2^k, arg2'=arg2P_2-k, [ arg2P_2+arg1P_1<=0 && k>=0 && -arg2P_2-2^(-1+k)+k+arg2P_2*2^(-1+k)+2^(-1+k)*arg1P_1>0 ], cost: 4+4*k Removed unreachable locations (and leaf rules with constant cost): Start location: __init 20: __init -> f4 : arg1'=1+arg2P_2*2^k-arg2P_2+k-2^k+arg1P_1*2^k, arg2'=arg2P_2-k, [ arg2P_2+arg1P_1<=0 && k>=0 && -arg2P_2-2^(-1+k)+k+arg2P_2*2^(-1+k)+2^(-1+k)*arg1P_1>0 ], cost: 4+4*k ### Computing asymptotic complexity ### Fully simplified ITS problem Start location: __init 20: __init -> f4 : arg1'=1+arg2P_2*2^k-arg2P_2+k-2^k+arg1P_1*2^k, arg2'=arg2P_2-k, [ arg2P_2+arg1P_1<=0 && k>=0 && -arg2P_2-2^(-1+k)+k+arg2P_2*2^(-1+k)+2^(-1+k)*arg1P_1>0 ], cost: 4+4*k Computing asymptotic complexity for rule 20 Resulting cost 0 has complexity: Unknown Obtained the following overall complexity (w.r.t. the length of the input n): Complexity: Constant Cpx degree: 0 Solved cost: 1 Rule cost: 1 Rule guard: [] WORST_CASE(Omega(1),?)