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: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + (6,4) app_A(x1,x2) = x1 + ((1,0),(1,1)) x2 + (2,2) uncurry_A() = (5,5) precedence: app# = app = uncurry partial status: pi(app#) = [1] pi(app) = [1, 2] pi(uncurry) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = (0,0) app_A(x1,x2) = ((1,0),(1,1)) x2 + (2,2) uncurry_A() = (1,1) precedence: app# = app > uncurry partial status: pi(app#) = [] pi(app) = [2] pi(uncurry) = [] The next rules are strictly ordered: p1 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#(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} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: 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 (no rules) Take the reduction pair: lexicographic combination of reduction pairs: 1. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = x1 + (2,2) app_A(x1,x2) = x1 + x2 + (2,2) uncurry_A() = (1,1) precedence: app# = uncurry > app partial status: pi(app#) = [1] pi(app) = [1, 2] pi(uncurry) = [] 2. weighted path order base order: matrix interpretations: carrier: N^2 order: lexicographic order interpretations: app#_A(x1,x2) = ((1,0),(1,1)) x1 + (2,2) app_A(x1,x2) = ((1,0),(0,0)) x1 + ((1,0),(0,0)) x2 + (2,1) uncurry_A() = (1,1) precedence: app# = app = uncurry partial status: pi(app#) = [1] pi(app) = [] pi(uncurry) = [] The next rules are strictly ordered: p1 We remove them from the problem. Then no dependency pair remains.