YES We show the termination of the TRS R: app(app(app(uncurry(),f),x),y) -> app(app(f,x),y) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: app#(app(app(uncurry(),f),x),y) -> app#(app(f,x),y) p2: app#(app(app(uncurry(),f),x),y) -> app#(f,x) and R consists of: r1: app(app(app(uncurry(),f),x),y) -> app(app(f,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: app#(app(app(uncurry(),f),x),y) -> app#(app(f,x),y) p2: app#(app(app(uncurry(),f),x),y) -> app#(f,x) and R consists of: r1: app(app(app(uncurry(),f),x),y) -> app(app(f,x),y) The set of usable rules consists of r1 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: app#_A(x1,x2) = max{14, x1 + 7} app_A(x1,x2) = max{19, x1 - 9, x2 + 17} uncurry_A = 31 precedence: app# = app = uncurry partial status: pi(app#) = [1] pi(app) = [2] pi(uncurry) = [] 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(uncurry(),f),x),y) -> app#(app(f,x),y) and R consists of: r1: app(app(app(uncurry(),f),x),y) -> app(app(f,x),y) 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(uncurry(),f),x),y) -> app#(app(f,x),y) and R consists of: r1: app(app(app(uncurry(),f),x),y) -> app(app(f,x),y) The set of usable rules consists of r1 Take the reduction pair: weighted path order base order: max/plus interpretations on natural numbers: app#_A(x1,x2) = max{2, x1 + 1, x2 + 1} app_A(x1,x2) = max{x1, x2 + 1} uncurry_A = 1 precedence: app# = app = uncurry partial status: pi(app#) = [1] pi(app) = [1, 2] pi(uncurry) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.