In the context of object-oriented systems, algorithms for building classhierarchies are currently receiving much attention. We present here a characterization of several globalalgorithms.A global algorithm is one which starts with only the set of classes (provided with all their properties) and directly buildsthe hierarchy.The algorithms scrutinized were developped each in a different framework.In this survey, they are explained in a single framework, which takesadvantage of a substructure of the Galois lattice associated with the binary relationmapping the classes to their properties.Their characterization allows to figure the results of the algorithms without runningthem in simple cases.This study once again highlights the Galois lattice as a main and intuitive model forclass hierarchies.
