YES We show the termination of the TRS R: h(x,c(y,z)) -> h(c(s(y),x),z) h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) p2: h#(c(s(x),c(s(|0|()),y)),z) -> h#(y,c(s(|0|()),c(x,z))) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The estimated dependency graph contains the following SCCs: {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) p2: h#(c(s(x),c(s(|0|()),y)),z) -> h#(y,c(s(|0|()),c(x,z))) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The set of usable rules consists of (no rules) Take the reduction pair: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h#_A(x1,x2) = x1 + ((0,0),(1,0)) x2 c_A(x1,x2) = x1 + x2 s_A(x1) = ((0,0),(1,0)) x1 |0|_A() = (1,1) The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: h#(x,c(y,z)) -> h#(c(s(y),x),z) and R consists of: r1: h(x,c(y,z)) -> h(c(s(y),x),z) r2: h(c(s(x),c(s(|0|()),y)),z) -> h(y,c(s(|0|()),c(x,z))) The set of usable rules consists of (no rules) Take the reduction pair: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h#_A(x1,x2) = ((1,0),(1,0)) x1 + ((1,0),(1,1)) x2 c_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (1,1) s_A(x1) = ((1,0),(1,1)) x1 + (0,1) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.