Rudiments of Calculus - Google Books

https://books.google.de/books?id=MkWZaiECJvQC&dq=Lemma+von+Arden&hl=de&source=gbs_navlinks_s

This book presents what in our opinion constitutes the basis of the theory of the mu-calculus, considered as an algebraic system rather than a logic. We have wished to present the subject in a unified way, and in a form as general as possible. Therefore,…