YES We show the termination of the TRS R: app(app(plus(),|0|()),y) -> y app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) app(app(app(curry(),f),x),y) -> app(app(f,x),y) add() -> app(curry(),plus()) Instead we prove termination of the uncurried system: app(curry_0(),y) -> curry_1(y) app(curry_1(x1),y) -> curry_2(x1,y) app(curry_2(x1,x2),y) -> curry_3(x1,x2,y) app(plus_0(),y) -> plus_1(y) app(plus_1(x1),y) -> plus_2(x1,y) app(s_0(),y) -> s_1(y) plus_2(|0|_0(),y) -> y plus_2(s_1(x),y) -> s_1(plus_2(x,y)) curry_3(f,x,y) -> app(app(f,x),y) add_0() -> curry_1(plus_0()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(curry_2(x1,x2),y) -> curry_3#(x1,x2,y) p2: app#(plus_1(x1),y) -> plus_2#(x1,y) p3: plus_2#(s_1(x),y) -> plus_2#(x,y) p4: curry_3#(f,x,y) -> app#(app(f,x),y) p5: curry_3#(f,x,y) -> app#(f,x) and R consists of: r1: app(curry_0(),y) -> curry_1(y) r2: app(curry_1(x1),y) -> curry_2(x1,y) r3: app(curry_2(x1,x2),y) -> curry_3(x1,x2,y) r4: app(plus_0(),y) -> plus_1(y) r5: app(plus_1(x1),y) -> plus_2(x1,y) r6: app(s_0(),y) -> s_1(y) r7: plus_2(|0|_0(),y) -> y r8: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r9: curry_3(f,x,y) -> app(app(f,x),y) r10: add_0() -> curry_1(plus_0()) The estimated dependency graph contains the following SCCs: {p1, p4, p5} {p3} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(curry_2(x1,x2),y) -> curry_3#(x1,x2,y) p2: curry_3#(f,x,y) -> app#(f,x) p3: curry_3#(f,x,y) -> app#(app(f,x),y) and R consists of: r1: app(curry_0(),y) -> curry_1(y) r2: app(curry_1(x1),y) -> curry_2(x1,y) r3: app(curry_2(x1,x2),y) -> curry_3(x1,x2,y) r4: app(plus_0(),y) -> plus_1(y) r5: app(plus_1(x1),y) -> plus_2(x1,y) r6: app(s_0(),y) -> s_1(y) r7: plus_2(|0|_0(),y) -> y r8: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r9: curry_3(f,x,y) -> app(app(f,x),y) r10: add_0() -> curry_1(plus_0()) The set of usable rules consists of r1, r2, r3, r4, r5, r6, r7, r8, r9 Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: app#_A(x1,x2) = x1 curry_2_A(x1,x2) = x1 + x2 + 4 curry_3#_A(x1,x2,x3) = x1 + x2 + 3 app_A(x1,x2) = x1 + x2 + 2 curry_0_A() = 2 curry_1_A(x1) = x1 + 3 curry_3_A(x1,x2,x3) = x1 + x2 + x3 + 5 plus_0_A() = 1 plus_1_A(x1) = x1 + 2 plus_2_A(x1,x2) = x2 + 3 s_0_A() = 2 s_1_A(x1) = 1 |0|_0_A() = 0 base order 2: marked-algebra reduction triple (>=A, >=A!, >A!): matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: app#_A(x1,x2) = x1 curry_2_A(x1,x2) = x1 + x2 + 5 curry_3#_A(x1,x2,x3) = x1 + x2 + 3 app_A(x1,x2) = x1 + x2 + 3 curry_0_A() = 4 curry_1_A(x1) = x1 + 2 curry_3_A(x1,x2,x3) = x1 + x2 + x3 + 6 plus_0_A() = 1 plus_1_A(x1) = x1 + 1 plus_2_A(x1,x2) = x2 + 2 s_0_A() = 2 s_1_A(x1) = 1 |0|_0_A() = 1 app#!_A(x1,x2) = x1 curry_2!_A(x1,x2) = 8 curry_3#!_A(x1,x2,x3) = 4 app!_A(x1,x2) = x1 + x2 + 5 curry_0!_A() = 9 curry_1!_A(x1) = 8 curry_3!_A(x1,x2,x3) = x1 + x2 + x3 + 9 plus_0!_A() = 0 plus_1!_A(x1) = 1 plus_2!_A(x1,x2) = 7 s_0!_A() = 7 s_1!_A(x1) = x1 + 6 |0|_0!_A() = 0 partial status: pi(app#) = [] pi(curry_2) = [] pi(curry_3#) = [] pi(app) = [2] pi(curry_0) = [] pi(curry_1) = [1] pi(curry_3) = [3] pi(plus_0) = [] pi(plus_1) = [] pi(plus_2) = [] pi(s_0) = [] pi(s_1) = [] pi(|0|_0) = [] The following rules are removed: p1, p2, p3 Then no dependency pair remains. -- 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(curry_0(),y) -> curry_1(y) r2: app(curry_1(x1),y) -> curry_2(x1,y) r3: app(curry_2(x1,x2),y) -> curry_3(x1,x2,y) r4: app(plus_0(),y) -> plus_1(y) r5: app(plus_1(x1),y) -> plus_2(x1,y) r6: app(s_0(),y) -> s_1(y) r7: plus_2(|0|_0(),y) -> y r8: plus_2(s_1(x),y) -> s_1(plus_2(x,y)) r9: curry_3(f,x,y) -> app(app(f,x),y) r10: add_0() -> curry_1(plus_0()) The set of usable rules consists of (no rules) Take the reduction pair: generalized weighted path order (>=MG, >G) base order 1: matrix interpretation with standard point-wise order: carrier: N^1 order: standard order interpretations: plus_2#_A(x1,x2) = x1 + x2 + 3 s_1_A(x1) = x1 + 2 base order 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 plus_2#!_A(x1,x2) = x1 + 3 s_1!_A(x1) = x1 + 2 partial status: pi(plus_2#) = [] pi(s_1) = [] The following rules are removed: p1 Then no dependency pair remains.