The illustration here definitely needs work. As it appears on my browser, all of the blank part of the 8 & 1/2 by 11-inch page below the diagram appears in the article, as does the page number, "1", at the bottom. Maybe I'll get to doing something about it, but if anyone out there can fix it quickly before I get to it, please do. 134.84.86.74 14:36, 14 Oct 2003 (UTC)

This definition of coalgebra is much too narrow for coalgebras as they appear in category theory and computer science. See, for instance, Jacobs and Rutten's "A Tutorial on (Co)Algebras and (Co)Induction".

Coalgebras are formally dual to algebras for a functor. It would be swell if someone included this much broader definition on this page (but I cannot volunteer today. Maybe some later day.).