categories: preprint: Left-determined model categories and universal homotopy theories

[rosicky@math.muni.cz (Jiri Rosicky)]

The following paper is available at
http://www.math.yorku.ca/Who/Faculty/Tholen/research.html

J.Rosicky and W.Tholen, Left-determined model categories and universal
homotopy theories

Abstract:
We say that a model category is left-determined if the weak
equivalences are generated (in a suitable sense) by the
cofibrations. While the model category of simplicial sets is not
left-determined, we show that its non-oriented variant, the
category of symmetric simplicial sets (in the sense of Lawvere
and Grandis) carries a natural left-determined model category
structure. This is used to give another and, as we believe,
simpler proof of a recent result of D. Dugger about universal
homotopy theories.