y D by ob(D) = !D!
|      and by letting D(X, Y) = C(X, Y) for each X, Y in !D!,
|      with composition and identities being the same as in C.
|      A routine check shows that D is a category.  We call it
|      the 'full subcategory' induced by !D!.  The &quot;full&quot; refers
|      to the fact that 'all' C-morphisms between objects in !D!
|      have been retained.
|
| Since no restrictions have been imposed on !D!,
| full subcategories give rise to a rich supply
| of new categories.  Even more genera