ABSTRACT
We have seen that the collection of all varieties of a given type forms a complete lattice, as does the collection of all clones of operations defined on a fixed set. These two lattices play an important role in universal algebra, but their study is made difficult by the fact that the lattices are large (usually uncountably infinite) and very complex. Thus we look for new approaches or tools to use in their study. One such approach is to try to study some smaller parts of the large lattice. Such smaller parts should have the same algebraic structure, so we are interested in the study of complete sublattices of a complete lattice.
