As the supersystem is thermally isolated from the rest of the universe, the second law can be expressed in the form ASS, Z 0 where the inequality applies if an irreversible change occurs anywhere in the supersystem, and the equality applies if there is no such irreversible change. In the limit of reversibility for the supersystem as a whole, if such a limit exists, ASS, is zero and eq 13 becomes
Assys : '_AI-Ires/{Tres (14)