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: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1,x2) = ((1,0),(1,0)) x1 + (1,1) s_A(x1) = ((1,1),(1,1)) x1 + (5,0) f_A(x1,x2) = ((1,1),(1,0)) x1 + (3,0) |0|_A() = (1,0) precedence: s = f = |0| > f# partial status: pi(f#) = [] pi(s) = [] pi(f) = [] pi(|0|) = [] 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: 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} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: 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 (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1,x2) = ((1,1),(1,1)) x1 + x2 + (2,2) s_A(x1) = x1 + (1,1) precedence: f# = s partial status: pi(f#) = [] pi(s) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.