YES We show the termination of the TRS R: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) p2: f#(x,f(a(),y)) -> f#(f(a(),h(f(a(),x))),y) p3: f#(x,f(a(),y)) -> f#(a(),h(f(a(),x))) p4: f#(x,f(a(),y)) -> f#(a(),x) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The estimated dependency graph contains the following SCCs: {p1, p2, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) p2: f#(x,f(a(),y)) -> f#(a(),x) p3: f#(x,f(a(),y)) -> f#(f(a(),h(f(a(),x))),y) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The set of usable rules consists of r1 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = x1 + x2 + (1,2) f_A(x1,x2) = x2 + (0,1) a_A() = (0,0) h_A(x1) = (0,0) precedence: f# = f = a = h partial status: pi(f#) = [] pi(f) = [] pi(a) = [] pi(h) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = (3,3) f_A(x1,x2) = (0,0) a_A() = (2,2) h_A(x1) = (1,1) precedence: h > f# = a > f partial status: pi(f#) = [] pi(f) = [] pi(a) = [] pi(h) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) p2: f#(x,f(a(),y)) -> f#(f(a(),h(f(a(),x))),y) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) p2: f#(x,f(a(),y)) -> f#(f(a(),h(f(a(),x))),y) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The set of usable rules consists of r1 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: max/plus interpretations on natural numbers: f#_A(x1,x2) = max{x1 + 11, x2 + 25} f_A(x1,x2) = max{12, x1, x2 + 7} a_A = 0 h_A(x1) = 1 precedence: f# > f = a = h partial status: pi(f#) = [1] pi(f) = [1] pi(a) = [] pi(h) = [] 2. weighted path order base order: max/plus interpretations on natural numbers: f#_A(x1,x2) = 0 f_A(x1,x2) = max{6, x1 - 4} a_A = 2 h_A(x1) = 19 precedence: f# = f = a = h partial status: pi(f#) = [] pi(f) = [] pi(a) = [] pi(h) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,f(a(),y)) -> f#(a(),f(f(a(),h(f(a(),x))),y)) and R consists of: r1: f(x,f(a(),y)) -> f(a(),f(f(a(),h(f(a(),x))),y)) The set of usable rules consists of r1 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = x2 f_A(x1,x2) = ((0,0),(1,0)) x1 + x2 a_A() = (1,2) h_A(x1) = (0,0) precedence: f > f# > a = h partial status: pi(f#) = [2] pi(f) = [] pi(a) = [] pi(h) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = x2 f_A(x1,x2) = (1,2) a_A() = (2,3) h_A(x1) = (1,1) precedence: f# = f = a = h partial status: pi(f#) = [2] pi(f) = [] pi(a) = [] pi(h) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.