The Copeland choice function an axiomatic characterization

We give a generalization of Copeland Scroes in a set of alternatives endowed with a complete binary relation. We then first study the links between Copeland scores and cycles. We provide a full axiomatic characterization for the Copeland choice rule and the Copeland ranking method.I am greatly indebted to Hervé Moulin who introduced me to the subject and helped me in many discussions. I have also a large debt do Jean-Luc Vila who gave me much advice