<Reference List> | |
Type: | Preprint |
National /International: | International |
Title: | A finitary adjoint functor theorem |
Publication Date: | 2023-11-23 |
Authors: |
- Jirí Adámek
- Lurdes Sousa |
Abstract: | Ranked locally finitely presentable categories are introduced, examples include categories of sets, vector spaces, posets, presheaves and boolean algebras. A finitary functor between ranked locally finitely presentable categories is proved to be a right adjoint if and only if it preserves countable limits. For endofunctors on vector spaces or pointed sets even countable products are sufficient. Surprisingly, for set functors there is a single exception of a (trivial) finitary functor preserving countable products but not countable limits. |
Institution: | DMUC 23-35 |
Online version: | http://www.mat.uc.pt...prints/eng_2023.html |
Download: | Not available |