0.00/0.20 YES 0.00/0.21 We consider the system theBenchmark. 0.00/0.21 0.00/0.21 Alphabet: 0.00/0.21 0.00/0.21 cons : [b * c] --> c 0.00/0.21 false : [] --> a 0.00/0.21 filter : [b -> a * c] --> c 0.00/0.21 filtersub : [a * b -> a * c] --> c 0.00/0.21 nil : [] --> c 0.00/0.21 true : [] --> a 0.00/0.21 0.00/0.21 Rules: 0.00/0.21 0.00/0.21 filter(f, nil) => nil 0.00/0.21 filter(f, cons(x, y)) => filtersub(f x, f, cons(x, y)) 0.00/0.21 filtersub(true, f, cons(x, y)) => cons(x, filter(f, y)) 0.00/0.21 filtersub(false, f, cons(x, y)) => filter(f, y) 0.00/0.21 0.00/0.21 This AFS is converted to an AFSM simply by replacing all free variables by meta-variables (with arity 0). 0.00/0.21 0.00/0.21 We use the dependency pair framework as described in [Kop12, Ch. 6/7], with static dependency pairs (see [KusIsoSakBla09] and the adaptation for AFSMs and accessible arguments in [Kop13]). 0.00/0.21 0.00/0.21 We thus obtain the following dependency pair problem (P_0, R_0, static, formative): 0.00/0.21 0.00/0.21 Dependency Pairs P_0: 0.00/0.21 0.00/0.21 0] filter#(F, cons(X, Y)) =#> filtersub#(F X, F, cons(X, Y)) 0.00/0.21 1] filtersub#(true, F, cons(X, Y)) =#> filter#(F, Y) 0.00/0.21 2] filtersub#(false, F, cons(X, Y)) =#> filter#(F, Y) 0.00/0.21 0.00/0.21 Rules R_0: 0.00/0.21 0.00/0.21 filter(F, nil) => nil 0.00/0.21 filter(F, cons(X, Y)) => filtersub(F X, F, cons(X, Y)) 0.00/0.21 filtersub(true, F, cons(X, Y)) => cons(X, filter(F, Y)) 0.00/0.21 filtersub(false, F, cons(X, Y)) => filter(F, Y) 0.00/0.21 0.00/0.21 Thus, the original system is terminating if (P_0, R_0, static, formative) is finite. 0.00/0.21 0.00/0.21 We consider the dependency pair problem (P_0, R_0, static, formative). 0.00/0.21 0.00/0.21 We apply the subterm criterion with the following projection function: 0.00/0.21 0.00/0.21 nu(filter#) = 2 0.00/0.21 nu(filtersub#) = 3 0.00/0.21 0.00/0.21 Thus, we can orient the dependency pairs as follows: 0.00/0.21 0.00/0.21 nu(filter#(F, cons(X, Y))) = cons(X, Y) = cons(X, Y) = nu(filtersub#(F X, F, cons(X, Y))) 0.00/0.21 nu(filtersub#(true, F, cons(X, Y))) = cons(X, Y) |> Y = nu(filter#(F, Y)) 0.00/0.21 nu(filtersub#(false, F, cons(X, Y))) = cons(X, Y) |> Y = nu(filter#(F, Y)) 0.00/0.21 0.00/0.21 By [Kop12, Thm. 7.35] and [Kop13, Thm. 5], we may replace a dependency pair problem (P_0, R_0, static, f) by (P_1, R_0, static, f), where P_1 contains: 0.00/0.21 0.00/0.21 filter#(F, cons(X, Y)) =#> filtersub#(F X, F, cons(X, Y)) 0.00/0.21 0.00/0.21 Thus, the original system is terminating if (P_1, R_0, static, formative) is finite. 0.00/0.21 0.00/0.21 We consider the dependency pair problem (P_1, R_0, static, formative). 0.00/0.21 0.00/0.21 We place the elements of P in a dependency graph approximation G (see e.g. [Kop12, Thm. 7.27, 7.29], as follows: 0.00/0.21 0.00/0.21 * 0 : 0.00/0.21 0.00/0.21 This graph has no strongly connected components. By [Kop12, Thm. 7.31], this implies finiteness of the dependency pair problem. 0.00/0.21 0.00/0.21 As all dependency pair problems were succesfully simplified with sound (and complete) processors until nothing remained, we conclude termination. 0.00/0.21 0.00/0.21 0.00/0.21 +++ Citations +++ 0.00/0.21 0.00/0.21 [Kop12] C. Kop. Higher Order Termination. PhD Thesis, 2012. 0.00/0.21 [Kop13] C. Kop. Static Dependency Pairs with Accessibility. Unpublished manuscript, http://cl-informatik.uibk.ac.at/users/kop/static.pdf, 2013. 0.00/0.21 [KusIsoSakBla09] K. Kusakari, Y. Isogai, M. Sakai, and F. Blanqui. Static Dependency Pair Method Based On Strong Computability for Higher-Order Rewrite Systems. In volume 92(10) of IEICE Transactions on Information and Systems. 2007--2015, 2009. 0.00/0.21 EOF