YES We show the termination of the TRS R: plus(plus(X,Y),Z) -> plus(X,plus(Y,Z)) times(X,s(Y)) -> plus(X,times(Y,X)) -- SCC decomposition. Consider the dependency pair problem (P, R), where P consists of p1: plus#(plus(X,Y),Z) -> plus#(X,plus(Y,Z)) p2: plus#(plus(X,Y),Z) -> plus#(Y,Z) p3: times#(X,s(Y)) -> plus#(X,times(Y,X)) p4: times#(X,s(Y)) -> times#(Y,X) and R consists of: r1: plus(plus(X,Y),Z) -> plus(X,plus(Y,Z)) r2: times(X,s(Y)) -> plus(X,times(Y,X)) The estimated dependency graph contains the following SCCs: {p4} {p1, p2} -- Reduction pair. Consider the dependency pair problem (P, R), where P consists of p1: times#(X,s(Y)) -> times#(Y,X) and R consists of: r1: plus(plus(X,Y),Z) -> plus(X,plus(Y,Z)) r2: times(X,s(Y)) -> plus(X,times(Y,X)) The set of usable rules consists of (no rules) Take the reduction pair: matrix interpretations: carrier: N^3 order: lexicographic order interpretations: times#_A(x1,x2) = ((0,0,0),(0,0,0),(1,0,0)) x1 + ((0,0,0),(0,0,0),(1,0,0)) x2 s_A(x1) = ((1,0,0),(0,1,0),(1,1,1)) x1 + (1,1,1) 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: plus#(plus(X,Y),Z) -> plus#(X,plus(Y,Z)) p2: plus#(plus(X,Y),Z) -> plus#(Y,Z) and R consists of: r1: plus(plus(X,Y),Z) -> plus(X,plus(Y,Z)) r2: times(X,s(Y)) -> plus(X,times(Y,X)) The set of usable rules consists of r1 Take the reduction pair: matrix interpretations: carrier: N^3 order: lexicographic order interpretations: plus#_A(x1,x2) = x1 plus_A(x1,x2) = ((1,0,0),(1,1,0),(0,0,0)) x1 + ((1,0,0),(0,0,0),(1,0,0)) x2 + (1,1,0) The next rules are strictly ordered: p1, p2 We remove them from the problem. Then no dependency pair remains.