I haven't really investigated, but I suspect that in the introductory math/phys/chem courses you'll find that variable names/values also change in various ways.  So in keeping track of what's "different or new", you end up not needing just dependencies but, realistically (in terms of reader convenience, but also due to difficulty of parsing OCR'd math problems to determine which are 'isomorphic'), all the problems from the latest edition.  Which might not quite be 'fair use.'<p>I am not sure about other courses like bio or psych.<p>Good luck solving the textbook problem, though ...