YES We show the termination of the TRS R: g(c(x,s(y))) -> g(c(s(x),y)) f(c(s(x),y)) -> f(c(x,s(y))) f(f(x)) -> f(d(f(x))) f(x) -> x -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: g#(c(x,s(y))) -> g#(c(s(x),y)) p2: f#(c(s(x),y)) -> f#(c(x,s(y))) p3: f#(f(x)) -> f#(d(f(x))) and R consists of: r1: g(c(x,s(y))) -> g(c(s(x),y)) r2: f(c(s(x),y)) -> f(c(x,s(y))) r3: f(f(x)) -> f(d(f(x))) r4: f(x) -> x The estimated dependency graph contains the following SCCs: {p1} {p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: g#(c(x,s(y))) -> g#(c(s(x),y)) and R consists of: r1: g(c(x,s(y))) -> g(c(s(x),y)) r2: f(c(s(x),y)) -> f(c(x,s(y))) r3: f(f(x)) -> f(d(f(x))) r4: f(x) -> x The set of usable rules consists of r1 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: g#_A(x1) = x1 c_A(x1,x2) = x1 + x2 s_A(x1) = x1 + 1 g_A(x1) = x1 g#!_A(x1) = 0 c!_A(x1,x2) = 1 s!_A(x1) = x1 + 2 g!_A(x1) = 3 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: g#_A(x1) = max{0, x1 - 7} c_A(x1,x2) = max{x1 - 1, x2 + 6} s_A(x1) = x1 g_A(x1) = max{0, x1 - 7} g#!_A(x1) = 0 c!_A(x1,x2) = max{x1 + 3, x2 + 4} s!_A(x1) = 1 g!_A(x1) = max{5, x1 - 1} partial status: pi(g#) = [1] pi(c) = [2] pi(s) = [1] pi(g) = [1] The following rules are removed: p1 Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(c(s(x),y)) -> f#(c(x,s(y))) and R consists of: r1: g(c(x,s(y))) -> g(c(s(x),y)) r2: f(c(s(x),y)) -> f(c(x,s(y))) r3: f(f(x)) -> f(d(f(x))) r4: f(x) -> x The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: f#_A(x1) = x1 c_A(x1,x2) = x1 + x2 s_A(x1) = x1 + 2 f#!_A(x1) = 2 c!_A(x1,x2) = x1 + 1 s!_A(x1) = 1 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: f#_A(x1) = max{0, x1 - 23} c_A(x1,x2) = max{15, x1 - 20} s_A(x1) = max{21, x1 + 15} f#!_A(x1) = max{4, x1 - 17} c!_A(x1,x2) = max{2, x1 - 18, x2 - 29} s!_A(x1) = max{2, x1 - 22} partial status: pi(f#) = [1] pi(c) = [2] pi(s) = [1] The following rules are removed: p1 Then no dependency pair remains.