YES We show the termination of the TRS R: f(j(x,y),y) -> g(f(x,k(y))) f(x,h1(y,z)) -> h2(|0|(),x,h1(y,z)) g(h2(x,y,h1(z,u))) -> h2(s(x),y,h1(z,u)) h2(x,j(y,h1(z,u)),h1(z,u)) -> h2(s(x),y,h1(s(z),u)) i(f(x,h(y))) -> y i(h2(s(x),y,h1(x,z))) -> z k(h(x)) -> h1(|0|(),x) k(h1(x,y)) -> h1(s(x),y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: f#(j(x,y),y) -> g#(f(x,k(y))) p2: f#(j(x,y),y) -> f#(x,k(y)) p3: f#(j(x,y),y) -> k#(y) p4: f#(x,h1(y,z)) -> h2#(|0|(),x,h1(y,z)) p5: g#(h2(x,y,h1(z,u))) -> h2#(s(x),y,h1(z,u)) p6: h2#(x,j(y,h1(z,u)),h1(z,u)) -> h2#(s(x),y,h1(s(z),u)) and R consists of: r1: f(j(x,y),y) -> g(f(x,k(y))) r2: f(x,h1(y,z)) -> h2(|0|(),x,h1(y,z)) r3: g(h2(x,y,h1(z,u))) -> h2(s(x),y,h1(z,u)) r4: h2(x,j(y,h1(z,u)),h1(z,u)) -> h2(s(x),y,h1(s(z),u)) r5: i(f(x,h(y))) -> y r6: i(h2(s(x),y,h1(x,z))) -> z r7: k(h(x)) -> h1(|0|(),x) r8: k(h1(x,y)) -> h1(s(x),y) The estimated dependency graph contains the following SCCs: {p2} {p6} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: f#(j(x,y),y) -> f#(x,k(y)) and R consists of: r1: f(j(x,y),y) -> g(f(x,k(y))) r2: f(x,h1(y,z)) -> h2(|0|(),x,h1(y,z)) r3: g(h2(x,y,h1(z,u))) -> h2(s(x),y,h1(z,u)) r4: h2(x,j(y,h1(z,u)),h1(z,u)) -> h2(s(x),y,h1(s(z),u)) r5: i(f(x,h(y))) -> y r6: i(h2(s(x),y,h1(x,z))) -> z r7: k(h(x)) -> h1(|0|(),x) r8: k(h1(x,y)) -> h1(s(x),y) The set of usable rules consists of r7, r8 Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = ((1,0),(0,0)) x1 + x2 + (1,3) j_A(x1,x2) = x1 + (4,6) k_A(x1) = ((1,0),(1,1)) x1 + (2,2) h_A(x1) = x1 + (1,1) h1_A(x1,x2) = x2 |0|_A() = (0,0) s_A(x1) = (1,1) precedence: f# = j = k = h = h1 = |0| = s partial status: pi(f#) = [] pi(j) = [] pi(k) = [] pi(h) = [] pi(h1) = [] pi(|0|) = [] pi(s) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: f#_A(x1,x2) = (0,0) j_A(x1,x2) = ((1,0),(0,0)) x1 + (1,1) k_A(x1) = ((1,0),(1,1)) x1 + (2,2) h_A(x1) = (3,2) h1_A(x1,x2) = (2,3) |0|_A() = (1,1) s_A(x1) = (1,1) precedence: j > k = h1 = s > f# = h = |0| partial status: pi(f#) = [] pi(j) = [] pi(k) = [] pi(h) = [] pi(h1) = [] pi(|0|) = [] pi(s) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains. -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: h2#(x,j(y,h1(z,u)),h1(z,u)) -> h2#(s(x),y,h1(s(z),u)) and R consists of: r1: f(j(x,y),y) -> g(f(x,k(y))) r2: f(x,h1(y,z)) -> h2(|0|(),x,h1(y,z)) r3: g(h2(x,y,h1(z,u))) -> h2(s(x),y,h1(z,u)) r4: h2(x,j(y,h1(z,u)),h1(z,u)) -> h2(s(x),y,h1(s(z),u)) r5: i(f(x,h(y))) -> y r6: i(h2(s(x),y,h1(x,z))) -> z r7: k(h(x)) -> h1(|0|(),x) r8: k(h1(x,y)) -> h1(s(x),y) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h2#_A(x1,x2,x3) = x2 + ((1,0),(1,1)) x3 + (1,1) j_A(x1,x2) = ((1,0),(1,1)) x1 + x2 + (3,7) h1_A(x1,x2) = x1 + (2,1) s_A(x1) = (1,2) precedence: j = h1 = s > h2# partial status: pi(h2#) = [2] pi(j) = [1, 2] pi(h1) = [1] pi(s) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: h2#_A(x1,x2,x3) = (0,0) j_A(x1,x2) = x1 + x2 + (1,1) h1_A(x1,x2) = (1,0) s_A(x1) = (1,0) precedence: j = s > h2# = h1 partial status: pi(h2#) = [] pi(j) = [] pi(h1) = [] pi(s) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.