YES We show the termination of the TRS R: app(app(plus(),|0|()),y) -> y app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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(plus(),app(s(),x)),y) -> app#(s(),app(app(plus(),x),y)) p2: app#(app(plus(),app(s(),x)),y) -> app#(app(plus(),x),y) p3: app#(app(plus(),app(s(),x)),y) -> app#(plus(),x) p4: app#(inc(),xs) -> app#(app(map(),app(plus(),app(s(),|0|()))),xs) p5: app#(inc(),xs) -> app#(map(),app(plus(),app(s(),|0|()))) p6: app#(inc(),xs) -> app#(plus(),app(s(),|0|())) p7: app#(inc(),xs) -> app#(s(),|0|()) p8: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(cons(),app(f,x)),app(app(map(),f),xs)) p9: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(cons(),app(f,x)) p10: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(f,x) p11: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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: {p4, p10, p11} {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#(f,x) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) p3: app#(inc(),xs) -> app#(app(map(),app(plus(),app(s(),|0|()))),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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: matrix interpretations: carrier: N^1 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + 3 app_A(x1,x2) = x2 + 4 map_A() = 2 cons_A() = 1 inc_A() = 17 plus_A() = 21 s_A() = 21 |0|_A() = 1 precedence: app# = app = map = cons = inc = plus = s = |0| partial status: pi(app#) = [1] pi(app) = [2] pi(map) = [] pi(cons) = [] pi(inc) = [] pi(plus) = [] pi(s) = [] pi(|0|) = [] The next rules are strictly ordered: p3 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) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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#(f,x) p2: app#(app(map(),f),app(app(cons(),x),xs)) -> app#(app(map(),f),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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: matrix interpretations: carrier: N^1 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + 3 app_A(x1,x2) = x2 + 4 map_A() = 6 cons_A() = 1 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#(app(map(),f),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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#(app(map(),f),xs) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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: matrix interpretations: carrier: N^1 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + x2 + 3 app_A(x1,x2) = x2 + 2 map_A() = 4 cons_A() = 1 precedence: app# = app = map = cons partial status: pi(app#) = [1, 2] 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. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(plus(),app(s(),x)),y) -> app#(app(plus(),x),y) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(inc(),xs) -> app(app(map(),app(plus(),app(s(),|0|()))),xs) 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: matrix interpretations: carrier: N^1 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + x2 + 4 app_A(x1,x2) = x2 + 2 plus_A() = 5 s_A() = 1 precedence: app = plus = s > app# partial status: pi(app#) = [] pi(app) = [2] pi(plus) = [] pi(s) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.