Abstract
Presheaf categories are well-known to be varieties of algebras and covarieties of coalgebras. We prove the converse: if a category is a variety as well as a covariety, then it is a presheaf category. Our main result is that all coalgebras on a set functor H form a presheaf category iff H is a reduction of a polynomial functor.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
