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()) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(plus(),app(s(),x)),y) -> app#(s(),app(app(plus(),x),y)) p2: app#(app(plus(),app(s(),x)),y) -> app#(app(plus(),x),y) p3: app#(app(plus(),app(s(),x)),y) -> app#(plus(),x) p4: app#(app(app(curry(),f),x),y) -> app#(app(f,x),y) p5: app#(app(app(curry(),f),x),y) -> app#(f,x) p6: add#() -> app#(curry(),plus()) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(app(app(curry(),f),x),y) -> app(app(f,x),y) r4: add() -> app(curry(),plus()) The estimated dependency graph contains the following SCCs: {p4, p5} {p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(app(curry(),f),x),y) -> app#(f,x) p2: app#(app(app(curry(),f),x),y) -> app#(app(f,x),y) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(app(app(curry(),f),x),y) -> app(app(f,x),y) r4: add() -> app(curry(),plus()) The set of usable rules consists of r1, r2, r3 Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: app#_A(x1,x2) = ((1,0),(0,0)) x1 + (6,1) app_A(x1,x2) = ((1,1),(0,0)) x1 + x2 + (1,0) curry_A() = (3,0) plus_A() = (1,1) |0|_A() = (1,1) s_A() = (5,0) precedence: app# = app = curry = s > |0| > plus partial status: pi(app#) = [] pi(app) = [] pi(curry) = [] pi(plus) = [] pi(|0|) = [] pi(s) = [] The next rules are strictly ordered: p2 We remove them from the problem. -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(app(curry(),f),x),y) -> app#(f,x) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(app(app(curry(),f),x),y) -> app(app(f,x),y) r4: add() -> app(curry(),plus()) The estimated dependency graph contains the following SCCs: {p1} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(app(curry(),f),x),y) -> app#(f,x) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(app(app(curry(),f),x),y) -> app(app(f,x),y) r4: add() -> app(curry(),plus()) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: app#_A(x1,x2) = ((1,0),(0,0)) x1 + (1,2) app_A(x1,x2) = ((1,0),(0,0)) x1 + ((1,0),(0,0)) x2 + (1,1) curry_A() = (2,1) precedence: app# = app = curry partial status: pi(app#) = [] pi(app) = [] pi(curry) = [] 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: app#(app(plus(),app(s(),x)),y) -> app#(app(plus(),x),y) and R consists of: r1: app(app(plus(),|0|()),y) -> y r2: app(app(plus(),app(s(),x)),y) -> app(s(),app(app(plus(),x),y)) r3: app(app(app(curry(),f),x),y) -> app(app(f,x),y) r4: add() -> app(curry(),plus()) The set of usable rules consists of (no rules) Take the reduction pair: weighted path order base order: matrix interpretations: carrier: N^2 order: standard order interpretations: app#_A(x1,x2) = ((1,0),(0,0)) x1 + x2 + (0,6) app_A(x1,x2) = x2 + (1,2) plus_A() = (3,5) s_A() = (4,1) precedence: app# = app > plus > s partial status: pi(app#) = [] pi(app) = [] pi(plus) = [] pi(s) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.