The theory of Mackey functors has been developed during the last 25 years in a series of papers by various authors (. Green [8], a. Dress [5], T. Yoshida [17], J. Th~venaz and P. Webb [13],[15],[14], G. Lewis [6]). It is an attempt to give a single framework for the different theories of representations of a finite group and its subgroups. The notion of Mackey functor for a group G can be essentially approached from three points of view: the first one ([8]), which I call "naive", relics on the poset of subgroups of G. The second one ([5],[17]) is more "categoric", and relies on the category.
