YES We show the termination of the TRS R: app(id(),x) -> x app(add(),|0|()) -> id() app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) app(app(map(),f),nil()) -> nil() app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(add(),app(s(),x)),y) -> app#(s(),app(app(add(),x),y)) p2: app#(app(add(),app(s(),x)),y) -> app#(app(add(),x),y) p3: app#(app(add(),app(s(),x)),y) -> app#(add(),x) p4: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(cons(),app(f,x)),app(app(map(),f),xs)) p5: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(cons(),app(f,x)) p6: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) p7: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The estimated dependency graph contains the following SCCs: {p2, p6, p7} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(add(),app(s(),x)),y) -> app#(app(add(),x),y) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) p3: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The set of usable rules consists of r2 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: app#_A(x1,x2) = x1 + 3 app_A(x1,x2) = max{x1 + 5, x2 + 6} add_A = 1 s_A = 2 map_A = 5 cons_A = 6 |0|_A = 4 id_A = 5 precedence: app# = app = add = s = map = cons = |0| = id partial status: pi(app#) = [1] pi(app) = [2] pi(add) = [] pi(s) = [] pi(map) = [] pi(cons) = [] pi(|0|) = [] pi(id) = [] The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: app#_A(x1,x2) = max{0, x2 - 8} app_A(x1,x2) = max{x1 + 5, x2 + 2} map_A = 1 cons_A = 0 precedence: app# = app = map = cons partial status: pi(app#) = [] pi(app) = [2] pi(map) = [] pi(cons) = [] The next rules are strictly ordered: p1 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) and R consists of: r1: app(id(),x) -> x r2: app(add(),|0|()) -> id() r3: app(app(add(),app(s(),x)),y) -> app(s(),app(app(add(),x),y)) r4: app(app(map(),f),nil()) -> nil() r5: app(app(map(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(f,x)),app(app(map(),f),xs)) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: app#_A(x1,x2) = x1 + 1 app_A(x1,x2) = max{5, x1 - 3, x2 + 2} map_A = 3 cons_A = 8 precedence: app# = app = map = cons partial status: pi(app#) = [1] pi(app) = [2] pi(map) = [] pi(cons) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.