YES We show the termination of the TRS R: app(id(),x) -> x app(plus(),|0|()) -> id() app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) Instead we prove termination of the uncurried system: app(id_0(),y) -> id_1(y) app(plus_0(),y) -> plus_1(y) app(plus_1(x1),y) -> plus_2(x1,y) app(s_0(),y) -> s_1(y) id_1(x) -> x plus_1(|0|_0()) -> id_0() plus_2(|0|_0(),y1) -> id_1(y1) plus_2(s_1(x),y) -> s_1(plus_2(x,y)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(id_0(),y) -> id_1#(y) p2: app#(plus_0(),y) -> plus_1#(y) p3: app#(plus_1(x1),y) -> plus_2#(x1,y) p4: plus_2#(|0|_0(),y1) -> id_1#(y1) p5: plus_2#(s_1(x),y) -> plus_2#(x,y) and R consists of: r1: app(id_0(),y) -> id_1(y) r2: app(plus_0(),y) -> plus_1(y) r3: app(plus_1(x1),y) -> plus_2(x1,y) r4: app(s_0(),y) -> s_1(y) r5: id_1(x) -> x r6: plus_1(|0|_0()) -> id_0() r7: plus_2(|0|_0(),y1) -> id_1(y1) r8: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) The estimated dependency graph contains the following SCCs: {p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: plus_2#(s_1(x),y) -> plus_2#(x,y) and R consists of: r1: app(id_0(),y) -> id_1(y) r2: app(plus_0(),y) -> plus_1(y) r3: app(plus_1(x1),y) -> plus_2(x1,y) r4: app(s_0(),y) -> s_1(y) r5: id_1(x) -> x r6: plus_1(|0|_0()) -> id_0() r7: plus_2(|0|_0(),y1) -> id_1(y1) r8: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >MG) base order 1: max/plus interpretation on natural numbers: plus_2#_A(x1,x2) = max{3, x1 + 1, x2 + 1} s_1_A(x1) = max{2, x1} base order 2: precedence: plus_2# > s_1 partial status: pi(plus_2#) = [1] pi(s_1) = [1] The following rules are removed: p1 Then no dependency pair remains.