YES We show the termination of the TRS R: f(|0|()) -> |1|() f(s(x)) -> g(f(x)) g(x) -> +(x,s(x)) f(s(x)) -> +(f(x),s(f(x))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(x)) -> g#(f(x)) p2: f#(s(x)) -> f#(x) p3: f#(s(x)) -> f#(x) and R consists of: r1: f(|0|()) -> |1|() r2: f(s(x)) -> g(f(x)) r3: g(x) -> +(x,s(x)) r4: f(s(x)) -> +(f(x),s(f(x))) The estimated dependency graph contains the following SCCs: {p2, p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(s(x)) -> f#(x) and R consists of: r1: f(|0|()) -> |1|() r2: f(s(x)) -> g(f(x)) r3: g(x) -> +(x,s(x)) r4: f(s(x)) -> +(f(x),s(f(x))) The set of usable rules consists of (no rules) Take the monotone reduction pair: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1) = x1 s_A(x1) = ((1,0),(1,1)) x1 + (1,1) The next rules are strictly ordered: p1 r1, r2, r3, r4 We remove them from the problem. Then no dependency pair remains.