YES We show the termination of the TRS R: f(x,c(y)) -> f(x,s(f(y,y))) f(s(x),y) -> f(x,s(c(y))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(x,c(y)) -> f#(x,s(f(y,y))) p2: f#(x,c(y)) -> f#(y,y) p3: f#(s(x),y) -> f#(x,s(c(y))) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) 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#(x,c(y)) -> f#(y,y) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) 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!): max/plus interpretation on natural numbers: f#_A(x1,x2) = max{x1, x2 - 3} c_A(x1) = max{14, x1 + 3} f#!_A(x1,x2) = max{1, x1 - 13, x2 - 15} c!_A(x1) = max{2, x1 - 39} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: f#_A(x1,x2) = max{x1, x2 - 7} c_A(x1) = x1 + 7 f#!_A(x1,x2) = max{3, x1 - 1, x2 - 3} c!_A(x1) = max{2, x1 - 2} partial status: pi(f#) = [] pi(c) = [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#(s(x),y) -> f#(x,s(c(y))) and R consists of: r1: f(x,c(y)) -> f(x,s(f(y,y))) r2: f(s(x),y) -> f(x,s(c(y))) 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!): max/plus interpretation on natural numbers: f#_A(x1,x2) = max{0, x1 - 13, x2 - 11} s_A(x1) = max{10, x1 + 7} c_A(x1) = max{2, x1 - 7} f#!_A(x1,x2) = max{4, x1 - 11, x2 - 15} s!_A(x1) = max{1, x1 - 18} c!_A(x1) = max{3, x1 - 33} 2. marked-algebra reduction triple (>=A, >=A!, >A!): max/plus interpretation on natural numbers: f#_A(x1,x2) = max{0, x1 - 15, x2 - 14} s_A(x1) = max{11, x1 + 8} c_A(x1) = max{5, x1 - 8} f#!_A(x1,x2) = max{4, x1 - 13, x2 - 17} s!_A(x1) = max{1, x1 - 14} c!_A(x1) = max{3, x1 - 23} partial status: pi(f#) = [1] pi(s) = [1] pi(c) = [] The following rules are removed: p1 Then no dependency pair remains.