YES We show the termination of the TRS R: app(app(mapt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) app(app(mapt(),f),app(node(),xs)) -> app(node(),app(app(maptlist(),f),xs)) app(app(maptlist(),f),nil()) -> nil() app(app(maptlist(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(app(mapt(),f),x)),app(app(maptlist(),f),xs)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapt(),f),app(leaf(),x)) -> app#(leaf(),app(f,x)) p2: app#(app(mapt(),f),app(leaf(),x)) -> app#(f,x) p3: app#(app(mapt(),f),app(node(),xs)) -> app#(node(),app(app(maptlist(),f),xs)) p4: app#(app(mapt(),f),app(node(),xs)) -> app#(app(maptlist(),f),xs) p5: app#(app(mapt(),f),app(node(),xs)) -> app#(maptlist(),f) p6: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(cons(),app(app(mapt(),f),x)),app(app(maptlist(),f),xs)) p7: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(cons(),app(app(mapt(),f),x)) p8: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(mapt(),f),x) p9: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(mapt(),f) p10: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(maptlist(),f),xs) and R consists of: r1: app(app(mapt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapt(),f),app(node(),xs)) -> app(node(),app(app(maptlist(),f),xs)) r3: app(app(maptlist(),f),nil()) -> nil() r4: app(app(maptlist(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(app(mapt(),f),x)),app(app(maptlist(),f),xs)) The estimated dependency graph contains the following SCCs: {p2, p4, p8, p10} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(mapt(),f),app(leaf(),x)) -> app#(f,x) p2: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(maptlist(),f),xs) p3: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(mapt(),f),x) p4: app#(app(mapt(),f),app(node(),xs)) -> app#(app(maptlist(),f),xs) and R consists of: r1: app(app(mapt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapt(),f),app(node(),xs)) -> app(node(),app(app(maptlist(),f),xs)) r3: app(app(maptlist(),f),nil()) -> nil() r4: app(app(maptlist(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(app(mapt(),f),x)),app(app(maptlist(),f),xs)) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (14,5) app_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(1,1)) x2 + (6,2) mapt_A() = (7,3) leaf_A() = (1,1) maptlist_A() = (0,0) cons_A() = (22,18) node_A() = (5,1) precedence: mapt = leaf = cons = node > app# = app = maptlist partial status: pi(app#) = [2] pi(app) = [] pi(mapt) = [] pi(leaf) = [] pi(maptlist) = [] pi(cons) = [] pi(node) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = (4,4) app_A(x1,x2) = (1,1) mapt_A() = (5,5) leaf_A() = (5,5) maptlist_A() = (2,2) cons_A() = (6,6) node_A() = (3,3) precedence: app > cons > leaf > app# > node > mapt > maptlist partial status: pi(app#) = [] pi(app) = [] pi(mapt) = [] pi(leaf) = [] pi(maptlist) = [] pi(cons) = [] pi(node) = [] The next rules are strictly ordered: p1, p2, p4 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(maptlist(),f),app(app(cons(),x),xs)) -> app#(app(mapt(),f),x) and R consists of: r1: app(app(mapt(),f),app(leaf(),x)) -> app(leaf(),app(f,x)) r2: app(app(mapt(),f),app(node(),xs)) -> app(node(),app(app(maptlist(),f),xs)) r3: app(app(maptlist(),f),nil()) -> nil() r4: app(app(maptlist(),f),app(app(cons(),x),xs)) -> app(app(cons(),app(app(mapt(),f),x)),app(app(maptlist(),f),xs)) The estimated dependency graph contains the following SCCs: (no SCCs)