0.00/0.08 YES 0.00/0.09 We consider the system theBenchmark. 0.00/0.09 0.00/0.09 Alphabet: 0.00/0.09 0.00/0.09 cons : [b * c] --> c 0.00/0.09 leaf : [a] --> b 0.00/0.09 mapt : [a -> a * b] --> b 0.00/0.09 maptlist : [a -> a * c] --> c 0.00/0.09 nil : [] --> c 0.00/0.09 node : [c] --> b 0.00/0.09 0.00/0.09 Rules: 0.00/0.09 0.00/0.09 mapt(f, leaf(x)) => leaf(f x) 0.00/0.09 mapt(f, node(x)) => node(maptlist(f, x)) 0.00/0.09 maptlist(f, nil) => nil 0.00/0.09 maptlist(f, cons(x, y)) => cons(mapt(f, x), maptlist(f, y)) 0.00/0.09 0.00/0.09 This AFS is converted to an AFSM simply by replacing all free variables by meta-variables (with arity 0). 0.00/0.09 0.00/0.09 We use rule removal, following [Kop12, Theorem 2.23]. 0.00/0.09 0.00/0.09 This gives the following requirements (possibly using Theorems 2.25 and 2.26 in [Kop12]): 0.00/0.09 0.00/0.09 mapt(F, leaf(X)) >? leaf(F X) 0.00/0.09 mapt(F, node(X)) >? node(maptlist(F, X)) 0.00/0.09 maptlist(F, nil) >? nil 0.00/0.09 maptlist(F, cons(X, Y)) >? cons(mapt(F, X), maptlist(F, Y)) 0.00/0.09 0.00/0.09 We orient these requirements with a polynomial interpretation in the natural numbers. 0.00/0.09 0.00/0.09 The following interpretation satisfies the requirements: 0.00/0.09 0.00/0.09 cons = \y0y1.2 + y1 + 2y0 0.00/0.09 leaf = \y0.y0 0.00/0.09 mapt = \G0y1.1 + 3y1 + G0(y1) + 2y1G0(y1) 0.00/0.09 maptlist = \G0y1.3y1 + G0(0) + G0(y1) + 2y1G0(y1) 0.00/0.09 nil = 0 0.00/0.09 node = \y0.1 + y0 0.00/0.09 0.00/0.09 Using this interpretation, the requirements translate to: 0.00/0.09 0.00/0.09 [[mapt(_F0, leaf(_x1))]] = 1 + 3x1 + F0(x1) + 2x1F0(x1) > x1 + F0(x1) = [[leaf(_F0 _x1)]] 0.00/0.09 [[mapt(_F0, node(_x1))]] = 4 + 3x1 + 2x1F0(1 + x1) + 3F0(1 + x1) > 1 + 3x1 + F0(0) + F0(x1) + 2x1F0(x1) = [[node(maptlist(_F0, _x1))]] 0.00/0.09 [[maptlist(_F0, nil)]] = 2F0(0) >= 0 = [[nil]] 0.00/0.09 [[maptlist(_F0, cons(_x1, _x2))]] = 6 + 3x2 + 6x1 + F0(0) + 2x2F0(2 + x2 + 2x1) + 4x1F0(2 + x2 + 2x1) + 5F0(2 + x2 + 2x1) > 4 + 3x2 + 6x1 + F0(0) + F0(x2) + 2x2F0(x2) + 2F0(x1) + 4x1F0(x1) = [[cons(mapt(_F0, _x1), maptlist(_F0, _x2))]] 0.00/0.09 0.00/0.09 We can thus remove the following rules: 0.00/0.09 0.00/0.09 mapt(F, leaf(X)) => leaf(F X) 0.00/0.09 mapt(F, node(X)) => node(maptlist(F, X)) 0.00/0.09 maptlist(F, cons(X, Y)) => cons(mapt(F, X), maptlist(F, Y)) 0.00/0.09 0.00/0.09 We use rule removal, following [Kop12, Theorem 2.23]. 0.00/0.09 0.00/0.09 This gives the following requirements (possibly using Theorems 2.25 and 2.26 in [Kop12]): 0.00/0.09 0.00/0.09 maptlist(F, nil) >? nil 0.00/0.09 0.00/0.09 We orient these requirements with a polynomial interpretation in the natural numbers. 0.00/0.09 0.00/0.09 The following interpretation satisfies the requirements: 0.00/0.09 0.00/0.09 maptlist = \G0y1.3 + 3y1 + G0(0) 0.00/0.09 nil = 0 0.00/0.09 0.00/0.09 Using this interpretation, the requirements translate to: 0.00/0.09 0.00/0.09 [[maptlist(_F0, nil)]] = 3 + F0(0) > 0 = [[nil]] 0.00/0.09 0.00/0.09 We can thus remove the following rules: 0.00/0.09 0.00/0.09 maptlist(F, nil) => nil 0.00/0.09 0.00/0.09 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. 0.00/0.09 0.00/0.09 0.00/0.09 +++ Citations +++ 0.00/0.09 0.00/0.09 [Kop12] C. Kop. Higher Order Termination. PhD Thesis, 2012. 0.00/0.09 EOF