Timeline for Has any attempt been made to classify finite groupoids?
Current License: CC BY-SA 3.0
12 events
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Jan 24 at 0:06 | comment | added | David Roberts♦ | Apparently there was a mistake, the real number of such groups is 49,487,367,289 cameroncounts.wordpress.com/2022/08/28/a-week-in-florida | |
Mar 26, 2015 at 20:44 | history | edited | Andrés E. Caicedo | CC BY-SA 3.0 |
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Feb 27, 2013 at 17:44 | comment | added | Benjamin Steinberg | Maybe discussion tea.mathoverflow.net/discussion/1545/downvoting-correct-answers/… is the place to discuss this. | |
Feb 27, 2013 at 17:42 | comment | added | Benjamin Steinberg | @Joel, this sounds like a good reason to downvote the question (which it seems you did) but not the answer. This answer explains why classifying even finite groups is hopeless in a very precise way and so implicitly answers the question. | |
Feb 27, 2013 at 17:26 | comment | added | Joël | @Benjamin: Sure, but then this fully answers the question. Obviously the OP was meaning his question as "can we do for groupoid as we have done for groups". As is clear now, he didn't thought his question thoroughly, because he didn't define what is an equivalence of groupoid for him, he didn't observe that for the most standard notion of equivalence, classifying groupies was essentially the same as classifying groups, and he overlooked the difference between classifying groups and classifying simple groups. | |
Feb 27, 2013 at 17:00 | comment | added | Benjamin Steinberg | @Joel, the previous answers had made clear that classifying finite groupoids is almost the same question as classifying finite groups. | |
Feb 27, 2013 at 15:33 | comment | added | Joël | I absolutely don't understand how this address the question: this answer doesn't even mention the word "groupoid". -1 | |
Nov 29, 2012 at 2:03 | comment | added | Benjamin Steinberg | This is similar to the phenomenon that 99% of all finite semigroups have a zero element and satisfy xyz=0. | |
Nov 28, 2012 at 21:09 | comment | added | Tom Leinster | I was so struck by this calculation that I had to spread the (old) news: golem.ph.utexas.edu/category/2012/11/… | |
Nov 27, 2012 at 16:22 | comment | added | Todd Trimble | Wow, thanks for the link and the factoid, Ben! | |
Nov 27, 2012 at 16:13 | comment | added | Nick Gill | Corrections: Breach -> Besche, O'Brian -> O'Brien. Also it might be worth mentioning that the number of ways of combining groups to get new ones is counted using second cohomology. The c-word should be enough to convince people that this is a highly non-trivial process. | |
Nov 27, 2012 at 16:05 | history | answered | Ben Fairbairn | CC BY-SA 3.0 |