YES We show the termination of the TRS R: div(X,e()) -> i(X) i(div(X,Y)) -> div(Y,X) div(div(X,Y),Z) -> div(Y,div(i(X),Z)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: div#(X,e()) -> i#(X) p2: i#(div(X,Y)) -> div#(Y,X) p3: div#(div(X,Y),Z) -> div#(Y,div(i(X),Z)) p4: div#(div(X,Y),Z) -> div#(i(X),Z) p5: div#(div(X,Y),Z) -> i#(X) and R consists of: r1: div(X,e()) -> i(X) r2: i(div(X,Y)) -> div(Y,X) r3: div(div(X,Y),Z) -> div(Y,div(i(X),Z)) The estimated dependency graph contains the following SCCs: {p1, p2, p3, p4, p5} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: div#(X,e()) -> i#(X) p2: i#(div(X,Y)) -> div#(Y,X) p3: div#(div(X,Y),Z) -> i#(X) p4: div#(div(X,Y),Z) -> div#(i(X),Z) p5: div#(div(X,Y),Z) -> div#(Y,div(i(X),Z)) and R consists of: r1: div(X,e()) -> i(X) r2: i(div(X,Y)) -> div(Y,X) r3: div(div(X,Y),Z) -> div(Y,div(i(X),Z)) The set of usable rules consists of r1, r2, r3 Take the reduction pair: lexicographic combination of reduction pairs: 1. matrix interpretations: carrier: N^4 order: lexicographic order interpretations: div#_A(x1,x2) = ((1,0,0,0),(1,1,0,0),(0,0,1,0),(0,0,1,1)) x1 + ((1,0,0,0),(0,1,0,0),(0,0,1,0),(1,1,1,1)) x2 + (0,0,6,0) e_A() = (1,1,1,1) i#_A(x1) = ((1,0,0,0),(1,0,0,0),(1,1,0,0),(1,0,0,0)) x1 + (0,6,0,5) div_A(x1,x2) = ((1,0,0,0),(1,1,0,0),(0,1,1,0),(0,1,0,1)) x1 + ((1,0,0,0),(0,1,0,0),(1,1,1,0),(1,1,1,1)) x2 + (4,1,1,1) i_A(x1) = ((1,0,0,0),(1,1,0,0),(0,0,1,0),(1,1,0,1)) x1 + (0,3,0,6) 2. lexicographic path order with precedence: precedence: div# > div > i > e > i# argument filter: pi(div#) = [1, 2] pi(e) = [] pi(i#) = [] pi(div) = [] pi(i) = 1 The next rules are strictly ordered: p1, p2, p3, p4, p5 We remove them from the problem. Then no dependency pair remains.