Timeline for Is there a notion of congruence relation for essentially algebraic structures?
Current License: CC BY-SA 2.5
6 events
| when toggle format | what | by | license | comment | |
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| Aug 21, 2010 at 9:04 | comment | added | Peter Arndt | Thanks for the explanation and all the references! (I have been offline for a week, hence the late reply) | |
| Aug 21, 2010 at 8:57 | vote | accept | Peter Arndt | ||
| Aug 14, 2010 at 18:54 | comment | added | SixWingedSeraph | Some colimits blow up even with algebraic theories. For example, the underlying set of the coproduct of two groups in the category of groups is not the coproduct (disjoint sum) of the underlying sets. | |
| Aug 13, 2010 at 2:11 | comment | added | SixWingedSeraph | Congruences on categories work very nicely when restricted to bijections on objects. This has attracted a lot of interest. Extension Theories for Categories, by Charles Wells. cwru.edu/artsci/math/wells/pub/pdf/catext.pdf For the following references I thank Peter Webb: An Introduction to the Representations and Cohomology of Categories, by Peter Webb. math.umn.edu/~webb/Publications/CategoryAlgebras.pdf G. Hoff, Cohomologies et extensions de categories, Math. Scand. 74 (1994), 191--207. H.-J. Baues and G. Wirsching, Cohomology of small categories, JPAA 38 | |
| Aug 13, 2010 at 2:01 | history | edited | SixWingedSeraph | CC BY-SA 2.5 |
Added info about effective equivalence relations.
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| Aug 13, 2010 at 1:42 | history | answered | SixWingedSeraph | CC BY-SA 2.5 |