By Mohamud Mohammed and Doron Zeilberger
Margo Kondratieva and Sergey Sadov's amazing historical discovery that Andrei Markov, of Markov Chains fame, "scooped" WZ (well, not quite!, read the article), turned out to be more than of historical value, since, while Markov lacked some of the central ideas of WZ theory, he also had an idea that WZ didn't have! If you add this on, you get a new-improved concept of WZ-pair, that we call MWZ pairs.
VERY IMPORTANT: This article is accompanied by the Maple packages