19 Feb
2014
19 Feb
'14
7:29 a.m.
Hello Cat Group, I have been reading http://www.tac.mta.ca/tac/reprints/articles/7/tr7abs.html as well as other works on groupoids .... I really like Higgins' book but in Chapter 1 I keep seeing allusions to "injections" and "surjections"instead of more general "monomorphisms" and "epimorphisms", respectively. Is this because of his assumption (and others ..) that starting point is a "small" graph, category, etc., i.e. sets not classes? If so, has anybody expanded treatment of groupoids beyond "sets" to "classes"? Also IMO "subgraphs" should be presented as as "monos" in the "graph category".... Kind regards, Vasili [For admin and other information see: http://www.mta.ca/~cat-dist/ ]