0.00/0.04 YES 0.00/0.04 We consider the system theBenchmark. 0.00/0.04 0.00/0.04 Alphabet: 0.00/0.04 0.00/0.04 0 : [] --> a 0.00/0.04 add : [a] --> a -> a 0.00/0.04 cons : [b * c] --> c 0.00/0.04 id : [] --> a -> a 0.00/0.04 map : [b -> b * c] --> c 0.00/0.04 nil : [] --> c 0.00/0.04 s : [a] --> a 0.00/0.04 0.00/0.04 Rules: 0.00/0.04 0.00/0.04 id x => x 0.00/0.04 add(0) => id 0.00/0.04 add(s(x)) y => s(add(x) y) 0.00/0.04 map(f, nil) => nil 0.00/0.04 map(f, cons(x, y)) => cons(f x, map(f, y)) 0.00/0.04 0.00/0.04 This AFS is converted to an AFSM simply by replacing all free variables by meta-variables (with arity 0). 0.00/0.04 0.00/0.04 We use rule removal, following [Kop12, Theorem 2.23]. 0.00/0.04 0.00/0.04 This gives the following requirements (possibly using Theorems 2.25 and 2.26 in [Kop12]): 0.00/0.04 0.00/0.04 id X >? X 0.00/0.04 add(0) >? id 0.00/0.04 add(s(X)) Y >? s(add(X) Y) 0.00/0.04 map(F, nil) >? nil 0.00/0.04 map(F, cons(X, Y)) >? cons(F X, map(F, Y)) 0.00/0.04 0.00/0.04 We orient these requirements with a polynomial interpretation in the natural numbers. 0.00/0.04 0.00/0.04 The following interpretation satisfies the requirements: 0.00/0.04 0.00/0.04 0 = 3 0.00/0.04 add = \y0y1.3 + 3y0 + 3y1 0.00/0.04 cons = \y0y1.3 + y0 + y1 0.00/0.04 id = \y0.3y0 0.00/0.04 map = \G0y1.3 + 3y1 + G0(y1) + 3y1G0(y1) 0.00/0.04 nil = 0 0.00/0.04 s = \y0.3 + y0 0.00/0.04 0.00/0.04 Using this interpretation, the requirements translate to: 0.00/0.04 0.00/0.04 [[id _x0]] = 4x0 >= x0 = [[_x0]] 0.00/0.04 [[add(0)]] = \y0.12 + 3y0 > \y0.3y0 = [[id]] 0.00/0.04 [[add(s(_x0)) _x1]] = 12 + 3x0 + 4x1 > 6 + 3x0 + 4x1 = [[s(add(_x0) _x1)]] 0.00/0.04 [[map(_F0, nil)]] = 3 + F0(0) > 0 = [[nil]] 0.00/0.04 [[map(_F0, cons(_x1, _x2))]] = 12 + 3x1 + 3x2 + 3x1F0(3 + x1 + x2) + 3x2F0(3 + x1 + x2) + 10F0(3 + x1 + x2) > 6 + x1 + 3x2 + F0(x1) + F0(x2) + 3x2F0(x2) = [[cons(_F0 _x1, map(_F0, _x2))]] 0.00/0.04 0.00/0.04 We can thus remove the following rules: 0.00/0.04 0.00/0.04 add(0) => id 0.00/0.04 add(s(X)) Y => s(add(X) Y) 0.00/0.04 map(F, nil) => nil 0.00/0.04 map(F, cons(X, Y)) => cons(F X, map(F, Y)) 0.00/0.04 0.00/0.04 We use rule removal, following [Kop12, Theorem 2.23]. 0.00/0.04 0.00/0.04 This gives the following requirements (possibly using Theorems 2.25 and 2.26 in [Kop12]): 0.00/0.04 0.00/0.04 id(X) >? X 0.00/0.04 0.00/0.04 We orient these requirements with a polynomial interpretation in the natural numbers. 0.00/0.04 0.00/0.04 The following interpretation satisfies the requirements: 0.00/0.04 0.00/0.04 id = \y0.1 + y0 0.00/0.04 0.00/0.04 Using this interpretation, the requirements translate to: 0.00/0.04 0.00/0.04 [[id(_x0)]] = 1 + x0 > x0 = [[_x0]] 0.00/0.04 0.00/0.04 We can thus remove the following rules: 0.00/0.04 0.00/0.04 id(X) => X 0.00/0.04 0.00/0.04 All rules were succesfully removed. Thus, termination of the original system has been reduced to termination of the beta-rule, which is well-known to hold. 0.00/0.04 0.00/0.04 0.00/0.04 +++ Citations +++ 0.00/0.04 0.00/0.04 [Kop12] C. Kop. Higher Order Termination. PhD Thesis, 2012. 0.00/0.04 EOF