Understanding the small object argument
Category Theory
2011-10-17 v2 Algebraic Topology
Abstract
The small object argument is a transfinite construction which, starting from a set of maps in a category, generates a weak factorisation system on that category. As useful as it is, the small object argument has some problematic aspects: it possesses no universal property; it does not converge; and it does not seem to be related to other transfinite constructions occurring in categorical algebra. In this paper, we give an "algebraic" refinement of the small object argument, cast in terms of Grandis and Tholen's natural weak factorisation systems, which rectifies each of these three deficiencies.
Keywords
Cite
@article{arxiv.0712.0724,
title = {Understanding the small object argument},
author = {Richard Garner},
journal= {arXiv preprint arXiv:0712.0724},
year = {2011}
}
Comments
42 pages; supersedes the earlier arXiv preprint math/0702290; v2: final journal version, minor corrections only