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. matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1,x2) = x1 s_A(x1) = ((1,1),(1,1)) x1 + (1,2) f_A(x1,x2) = ((0,1),(1,1)) x1 + (0,1) |0|_A() = (1,2) 2. matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1,x2) = ((1,1),(0,0)) x1 s_A(x1) = ((1,1),(1,1)) x1 + (2,1) f_A(x1,x2) = (1,1) |0|_A() = (2,2) 3. matrix interpretations: carrier: N^2 order: standard order interpretations: f#_A(x1,x2) = ((0,1),(0,0)) x1 s_A(x1) = ((0,0),(1,0)) x1 + (1,2) f_A(x1,x2) = (1,1) |0|_A() = (2,2) The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.