YES We show the termination of the TRS R: +(|0|(),y) -> y +(s(x),|0|()) -> s(x) +(s(x),s(y)) -> s(+(s(x),+(y,|0|()))) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: +#(s(x),s(y)) -> +#(s(x),+(y,|0|())) p2: +#(s(x),s(y)) -> +#(y,|0|()) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),|0|()) -> s(x) r3: +(s(x),s(y)) -> s(+(s(x),+(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: +#(s(x),s(y)) -> +#(s(x),+(y,|0|())) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),|0|()) -> s(x) r3: +(s(x),s(y)) -> s(+(s(x),+(y,|0|()))) The set of usable rules consists of r1, r2 Take the reduction pair: matrix interpretations: carrier: N^4 order: lexicographic order interpretations: +#_A(x1,x2) = ((1,0,0,0),(0,1,0,0),(0,0,1,0),(0,1,1,1)) x1 + ((1,0,0,0),(0,1,0,0),(1,1,1,0),(1,1,1,1)) x2 s_A(x1) = ((1,0,0,0),(1,1,0,0),(1,1,1,0),(0,1,0,0)) x1 + (2,1,1,2) +_A(x1,x2) = ((1,0,0,0),(1,1,0,0),(1,1,1,0),(0,1,0,0)) x1 + ((1,0,0,0),(0,1,0,0),(1,0,1,0),(0,0,0,0)) x2 + (0,3,0,0) |0|_A() = (1,1,1,1) The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.