YES

   1: f(f(x1,x2),x3) -> f(x1,f(x2,x3))
   2: f(1(),x1) -> x1

@Jouannaud and Kirchner's criterion
--- R
   1: f(f(x1,x2),x3) -> f(x1,f(x2,x3))
   2: f(1(),x1) -> x1

--- S
   1: f(f(x1,x2),x3) -> f(x1,f(x2,x3))
   2: f(1(),x1) -> x1