Rational terms (possibly infinite terms with finitely many subterms) can be represented in a finite way via Μ-terms, that is, terms over a signature extended with self-instantiation operators. For example, f w = f(f(f(...))) can be represented as Μx.f(x) (or also as Μ x .f(f(x)), f(Μx.f(x)), ...). Now, if we reduce a Μ-term t to s via a rewriting rule using standard notions of the theory of Term Rewriting Systems, how are the rational terms corresponding to t and to s related?