Problem:
 f(s(x),x) -> f(s(x),round(x))
 round(0()) -> 0()
 round(0()) -> s(0())
 round(s(0())) -> s(0())
 round(s(s(x))) -> s(s(round(x)))

Proof:
 Unfolding Processor:
  loop length: 2
  terms:
   f(s(0()),0())
   f(s(0()),round(0()))
  context: []
  substitution:
   
  Qed