YES We show the termination of the TRS R: g(|0|(),f(x,x)) -> x g(x,s(y)) -> g(f(x,y),|0|()) g(s(x),y) -> g(f(x,y),|0|()) g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: g#(x,s(y)) -> g#(f(x,y),|0|()) p2: g#(s(x),y) -> g#(f(x,y),|0|()) p3: g#(f(x,y),|0|()) -> g#(x,|0|()) p4: g#(f(x,y),|0|()) -> g#(y,|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) The estimated dependency graph contains the following SCCs: {p2, p3, p4} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: g#(f(x,y),|0|()) -> g#(x,|0|()) p2: g#(f(x,y),|0|()) -> g#(y,|0|()) p3: g#(s(x),y) -> g#(f(x,y),|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: g#_A(x1,x2) = x1 + ((1,0),(0,0)) x2 + (1,4) f_A(x1,x2) = ((1,0),(1,1)) x1 + ((1,0),(1,1)) x2 + (3,5) |0|_A() = (1,3) s_A(x1) = ((1,0),(0,0)) x1 + (6,2) precedence: g# = f = |0| = s partial status: pi(g#) = [] pi(f) = [] pi(|0|) = [] pi(s) = [] 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: g#(f(x,y),|0|()) -> g#(x,|0|()) p2: g#(s(x),y) -> g#(f(x,y),|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) 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#(f(x,y),|0|()) -> g#(x,|0|()) p2: g#(s(x),y) -> g#(f(x,y),|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: g#_A(x1,x2) = x1 f_A(x1,x2) = x1 |0|_A() = (1,1) s_A(x1) = x1 + (1,2) precedence: g# = f = s > |0| partial status: pi(g#) = [] pi(f) = [] pi(|0|) = [] pi(s) = [] 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: g#(f(x,y),|0|()) -> g#(x,|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: g#(f(x,y),|0|()) -> g#(x,|0|()) and R consists of: r1: g(|0|(),f(x,x)) -> x r2: g(x,s(y)) -> g(f(x,y),|0|()) r3: g(s(x),y) -> g(f(x,y),|0|()) r4: g(f(x,y),|0|()) -> f(g(x,|0|()),g(y,|0|())) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: g#_A(x1,x2) = ((0,0),(1,0)) x1 + (1,1) f_A(x1,x2) = ((1,0),(0,0)) x1 + x2 + (3,6) |0|_A() = (2,5) precedence: g# = f = |0| partial status: pi(g#) = [] pi(f) = [2] pi(|0|) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.