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 r5, r7 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: trivial reduction triple (T x T, T x T, Φ) base order 2: lexicographic combination of reduction triples: 1. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: plus_2#_A(x1,x2) = x1 s_1_A(x1) = x1 + 2 id_1_A(x1) = x1 + 2 plus_2_A(x1,x2) = x1 + x2 + 4 |0|_0_A() = 1 plus_2#!_A(x1,x2) = x1 + 5 s_1!_A(x1) = x1 + 4 id_1!_A(x1) = 2 plus_2!_A(x1,x2) = x1 + 5 |0|_0!_A() = 4 2. marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: plus_2#_A(x1,x2) = x1 s_1_A(x1) = x1 + 2 id_1_A(x1) = x1 + 6 plus_2_A(x1,x2) = x1 + x2 + 5 |0|_0_A() = 1 plus_2#!_A(x1,x2) = 3 s_1!_A(x1) = x1 + 2 id_1!_A(x1) = 0 plus_2!_A(x1,x2) = x1 + 4 |0|_0!_A() = 2 partial status: pi(plus_2#) = [] pi(s_1) = [1] pi(id_1) = [1] pi(plus_2) = [2] pi(|0|_0) = [] The following rules are removed: p1 Then no dependency pair remains.