YES We show the termination of the TRS R: f(|0|(),y) -> |0|() f(s(x),y) -> f(f(x,y),y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(x),y) -> f#(f(x,y),y) p2: f#(s(x),y) -> f#(x,y) and R consists of: r1: f(|0|(),y) -> |0|() r2: f(s(x),y) -> f(f(x,y),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#(s(x),y) -> f#(f(x,y),y) p2: f#(s(x),y) -> f#(x,y) and R consists of: r1: f(|0|(),y) -> |0|() r2: f(s(x),y) -> f(f(x,y),y) The set of usable rules consists of r1, r2 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 + (4,5) s_A(x1) = ((1,0),(1,1)) x1 + (3,6) f_A(x1,x2) = ((1,0),(1,1)) x1 + (1,2) |0|_A() = (1,1) precedence: f# = s = f = |0| partial status: pi(f#) = [] pi(s) = [] pi(f) = [] pi(|0|) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = ((1,0),(0,0)) x1 s_A(x1) = ((1,0),(1,1)) x1 + (3,3) f_A(x1,x2) = (2,2) |0|_A() = (1,1) precedence: f# > s = f = |0| partial status: pi(f#) = [] pi(s) = [] pi(f) = [] pi(|0|) = [] The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.