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 : [] --> b 0.00/0.04 cons : [a * b] --> b 0.00/0.04 nil : [] --> b 0.00/0.04 plus : [b * b] --> b 0.00/0.04 s : [b] --> b 0.00/0.04 sumwith : [a -> b * b] --> b 0.00/0.04 0.00/0.04 Rules: 0.00/0.04 0.00/0.04 plus(0, x) => x 0.00/0.04 plus(s(x), y) => s(plus(x, y)) 0.00/0.04 sumwith(f, nil) => nil 0.00/0.04 sumwith(f, cons(x, y)) => plus(f x, sumwith(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 plus(0, X) >? X 0.00/0.04 plus(s(X), Y) >? s(plus(X, Y)) 0.00/0.04 sumwith(F, nil) >? nil 0.00/0.04 sumwith(F, cons(X, Y)) >? plus(F X, sumwith(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 cons = \y0y1.3 + 3y0 + 3y1 0.00/0.04 nil = 0 0.00/0.04 plus = \y0y1.1 + y0 + y1 0.00/0.04 s = \y0.y0 0.00/0.04 sumwith = \G0y1.3 + 3y1 + G0(0) + 2y1G0(y1) 0.00/0.04 0.00/0.04 Using this interpretation, the requirements translate to: 0.00/0.04 0.00/0.04 [[plus(0, _x0)]] = 4 + x0 > x0 = [[_x0]] 0.00/0.04 [[plus(s(_x0), _x1)]] = 1 + x0 + x1 >= 1 + x0 + x1 = [[s(plus(_x0, _x1))]] 0.00/0.04 [[sumwith(_F0, nil)]] = 3 + F0(0) > 0 = [[nil]] 0.00/0.04 [[sumwith(_F0, cons(_x1, _x2))]] = 12 + 9x1 + 9x2 + F0(0) + 6x1F0(3 + 3x1 + 3x2) + 6x2F0(3 + 3x1 + 3x2) + 6F0(3 + 3x1 + 3x2) > 4 + x1 + 3x2 + F0(0) + F0(x1) + 2x2F0(x2) = [[plus(_F0 _x1, sumwith(_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 plus(0, X) => X 0.00/0.04 sumwith(F, nil) => nil 0.00/0.04 sumwith(F, cons(X, Y)) => plus(F X, sumwith(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 plus(s(X), Y) >? s(plus(X, 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 plus = \y0y1.y1 + 3y0 0.00/0.04 s = \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 [[plus(s(_x0), _x1)]] = 3 + x1 + 3x0 > 1 + x1 + 3x0 = [[s(plus(_x0, _x1))]] 0.00/0.04 0.00/0.04 We can thus remove the following rules: 0.00/0.04 0.00/0.04 plus(s(X), Y) => s(plus(X, Y)) 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