人から借りてきた2セント
http://caml.inria.fr/pub/ml-archives/caml-list/1996/09/6fe7d80e0e84d33d8f84ce6923904873.en.html
> If we take all finite and infinite lists, one would take the
> terminal co--algebra or greatest fixpoint semantics.Hmph. If it's not the least fixpoint, it must be the greatest
fixpoint? No, there are interesting in-betweens.