YES We show the termination of the TRS R: from(X) -> cons(X,n__from(n__s(X))) head(cons(X,XS)) -> X |2nd|(cons(X,XS)) -> head(activate(XS)) take(|0|(),XS) -> nil() take(s(N),cons(X,XS)) -> cons(X,n__take(N,activate(XS))) sel(|0|(),cons(X,XS)) -> X sel(s(N),cons(X,XS)) -> sel(N,activate(XS)) from(X) -> n__from(X) s(X) -> n__s(X) take(X1,X2) -> n__take(X1,X2) activate(n__from(X)) -> from(activate(X)) activate(n__s(X)) -> s(activate(X)) activate(n__take(X1,X2)) -> take(activate(X1),activate(X2)) activate(X) -> X -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: |2nd|#(cons(X,XS)) -> head#(activate(XS)) p2: |2nd|#(cons(X,XS)) -> activate#(XS) p3: take#(s(N),cons(X,XS)) -> activate#(XS) p4: sel#(s(N),cons(X,XS)) -> sel#(N,activate(XS)) p5: sel#(s(N),cons(X,XS)) -> activate#(XS) p6: activate#(n__from(X)) -> from#(activate(X)) p7: activate#(n__from(X)) -> activate#(X) p8: activate#(n__s(X)) -> s#(activate(X)) p9: activate#(n__s(X)) -> activate#(X) p10: activate#(n__take(X1,X2)) -> take#(activate(X1),activate(X2)) p11: activate#(n__take(X1,X2)) -> activate#(X1) p12: activate#(n__take(X1,X2)) -> activate#(X2) and R consists of: r1: from(X) -> cons(X,n__from(n__s(X))) r2: head(cons(X,XS)) -> X r3: |2nd|(cons(X,XS)) -> head(activate(XS)) r4: take(|0|(),XS) -> nil() r5: take(s(N),cons(X,XS)) -> cons(X,n__take(N,activate(XS))) r6: sel(|0|(),cons(X,XS)) -> X r7: sel(s(N),cons(X,XS)) -> sel(N,activate(XS)) r8: from(X) -> n__from(X) r9: s(X) -> n__s(X) r10: take(X1,X2) -> n__take(X1,X2) r11: activate(n__from(X)) -> from(activate(X)) r12: activate(n__s(X)) -> s(activate(X)) r13: activate(n__take(X1,X2)) -> take(activate(X1),activate(X2)) r14: activate(X) -> X The estimated dependency graph contains the following SCCs: {p4} {p3, p7, p9, p10, p11, p12} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: sel#(s(N),cons(X,XS)) -> sel#(N,activate(XS)) and R consists of: r1: from(X) -> cons(X,n__from(n__s(X))) r2: head(cons(X,XS)) -> X r3: |2nd|(cons(X,XS)) -> head(activate(XS)) r4: take(|0|(),XS) -> nil() r5: take(s(N),cons(X,XS)) -> cons(X,n__take(N,activate(XS))) r6: sel(|0|(),cons(X,XS)) -> X r7: sel(s(N),cons(X,XS)) -> sel(N,activate(XS)) r8: from(X) -> n__from(X) r9: s(X) -> n__s(X) r10: take(X1,X2) -> n__take(X1,X2) r11: activate(n__from(X)) -> from(activate(X)) r12: activate(n__s(X)) -> s(activate(X)) r13: activate(n__take(X1,X2)) -> take(activate(X1),activate(X2)) r14: activate(X) -> X The set of usable rules consists of r1, r4, r5, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: sel#_A(x1,x2) = max{42, x1 + 39} s_A(x1) = max{70, x1 + 29} cons_A(x1,x2) = 27 activate_A(x1) = max{41, x1} from_A(x1) = 27 n__from_A(x1) = 10 n__s_A(x1) = max{70, x1 + 29} take_A(x1,x2) = max{82, x2 + 12} |0|_A = 1 nil_A = 0 n__take_A(x1,x2) = max{82, x2 + 12} precedence: sel# = activate > s > from = n__s > n__from = take > cons = |0| = nil = n__take partial status: pi(sel#) = [1] pi(s) = [1] pi(cons) = [] pi(activate) = [1] pi(from) = [] pi(n__from) = [] pi(n__s) = [1] pi(take) = [2] pi(|0|) = [] pi(nil) = [] pi(n__take) = [2] 2. weighted path order base order: max/plus interpretations on natural numbers: sel#_A(x1,x2) = max{4, x1} s_A(x1) = x1 + 17 cons_A(x1,x2) = 4 activate_A(x1) = max{5, x1 - 1} from_A(x1) = 4 n__from_A(x1) = 6 n__s_A(x1) = x1 + 23 take_A(x1,x2) = max{4, x2} |0|_A = 4 nil_A = 1 n__take_A(x1,x2) = max{4, x2} precedence: activate > nil > from > sel# = cons = take > n__take > s = n__from = n__s = |0| partial status: pi(sel#) = [1] pi(s) = [1] pi(cons) = [] pi(activate) = [] pi(from) = [] pi(n__from) = [] pi(n__s) = [] pi(take) = [] pi(|0|) = [] pi(nil) = [] pi(n__take) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: take#(s(N),cons(X,XS)) -> activate#(XS) p2: activate#(n__take(X1,X2)) -> activate#(X2) p3: activate#(n__take(X1,X2)) -> activate#(X1) p4: activate#(n__take(X1,X2)) -> take#(activate(X1),activate(X2)) p5: activate#(n__s(X)) -> activate#(X) p6: activate#(n__from(X)) -> activate#(X) and R consists of: r1: from(X) -> cons(X,n__from(n__s(X))) r2: head(cons(X,XS)) -> X r3: |2nd|(cons(X,XS)) -> head(activate(XS)) r4: take(|0|(),XS) -> nil() r5: take(s(N),cons(X,XS)) -> cons(X,n__take(N,activate(XS))) r6: sel(|0|(),cons(X,XS)) -> X r7: sel(s(N),cons(X,XS)) -> sel(N,activate(XS)) r8: from(X) -> n__from(X) r9: s(X) -> n__s(X) r10: take(X1,X2) -> n__take(X1,X2) r11: activate(n__from(X)) -> from(activate(X)) r12: activate(n__s(X)) -> s(activate(X)) r13: activate(n__take(X1,X2)) -> take(activate(X1),activate(X2)) r14: activate(X) -> X The set of usable rules consists of r1, r4, r5, r8, r9, r10, r11, r12, r13, r14 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: take#_A(x1,x2) = x2 + 6 s_A(x1) = max{15, x1 + 3} cons_A(x1,x2) = max{x1 + 7, x2 - 4} activate#_A(x1) = max{13, x1 + 2} n__take_A(x1,x2) = max{x1 + 11, x2 + 10} activate_A(x1) = x1 n__s_A(x1) = max{15, x1 + 3} n__from_A(x1) = max{27, x1 + 16} from_A(x1) = max{27, x1 + 16} take_A(x1,x2) = max{x1 + 11, x2 + 10} |0|_A = 1 nil_A = 0 precedence: take# = s = activate = n__s = from > take = |0| > activate# = n__from > n__take > cons > nil partial status: pi(take#) = [2] pi(s) = [1] pi(cons) = [] pi(activate#) = [1] pi(n__take) = [1, 2] pi(activate) = [1] pi(n__s) = [] pi(n__from) = [1] pi(from) = [1] pi(take) = [1, 2] pi(|0|) = [] pi(nil) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: take#_A(x1,x2) = max{59, x2 + 1} s_A(x1) = max{60, x1 + 22} cons_A(x1,x2) = 60 activate#_A(x1) = 59 n__take_A(x1,x2) = 0 activate_A(x1) = 57 n__s_A(x1) = 19 n__from_A(x1) = x1 + 19 from_A(x1) = max{61, x1 + 20} take_A(x1,x2) = max{57, x1} |0|_A = 29 nil_A = 30 precedence: from = |0| = nil > s > activate > activate# = take > take# = cons = n__take = n__s = n__from partial status: pi(take#) = [2] pi(s) = [] pi(cons) = [] pi(activate#) = [] pi(n__take) = [] pi(activate) = [] pi(n__s) = [] pi(n__from) = [1] pi(from) = [] pi(take) = [] pi(|0|) = [] pi(nil) = [] The next rules are strictly ordered: p1, p2, p3, p4, p5, p6 We remove them from the problem. Then no dependency pair remains.