YES We show the termination of the TRS R: +(|0|(),y) -> y +(s(x),y) -> s(+(x,y)) -(|0|(),y) -> |0|() -(x,|0|()) -> x -(s(x),s(y)) -> -(x,y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: +#(s(x),y) -> +#(x,y) p2: -#(s(x),s(y)) -> -#(x,y) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: -(|0|(),y) -> |0|() r4: -(x,|0|()) -> x r5: -(s(x),s(y)) -> -(x,y) The estimated dependency graph contains the following SCCs: {p1} {p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: +#(s(x),y) -> +#(x,y) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: -(|0|(),y) -> |0|() r4: -(x,|0|()) -> x r5: -(s(x),s(y)) -> -(x,y) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: +# > s argument filter: pi(+#) = [1, 2] pi(s) = 1 2. lexicographic path order with precedence: precedence: s > +# argument filter: pi(+#) = 1 pi(s) = 1 3. lexicographic path order with precedence: precedence: s > +# argument filter: pi(+#) = [1] pi(s) = [1] 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: -#(s(x),s(y)) -> -#(x,y) and R consists of: r1: +(|0|(),y) -> y r2: +(s(x),y) -> s(+(x,y)) r3: -(|0|(),y) -> |0|() r4: -(x,|0|()) -> x r5: -(s(x),s(y)) -> -(x,y) The set of usable rules consists of (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. lexicographic path order with precedence: precedence: s > -# argument filter: pi(-#) = 1 pi(s) = [1] 2. lexicographic path order with precedence: precedence: s > -# argument filter: pi(-#) = 1 pi(s) = 1 3. lexicographic path order with precedence: precedence: s > -# argument filter: pi(-#) = 1 pi(s) = [1] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.