Timeline for Why are Regular Categories assumed to be finitely complete?
Current License: CC BY-SA 3.0
9 events
| when toggle format | what | by | license | comment | |
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| Feb 13, 2018 at 9:50 | comment | added | David Roberts♦ | @Peter "I resisted this for quite a while, because I don't really want people to buy `Topos Theory' (I'd much rather they bought copies of the Elephant), but in the end I had to concede that Dover knew their business better than I did, and if they said there was a market for it they were probably right." Peter Johnstone, categories mailing list, 6 March 2014 | |
| Feb 13, 2018 at 9:13 | comment | added | Peter LeFanu Lumsdaine | @DavidRoberts: does Johnstone really say that? I find the earlier book excellent, and very different from the Elephant in what it’s good for. | |
| Feb 13, 2018 at 0:44 | comment | added | David Roberts♦ | @Tyler the 'Baby Elephant' is available as an inexpensive Dover reprint, and despite what Johnstone says ("don't buy it, buy the Elephant instead") it's still a handy book. | |
| Feb 12, 2018 at 23:41 | comment | added | Tyler Bryson | It's interesting. I've been building up my own notes on a related idea---proving everything along the way. I keep expecting to need more limits but I haven't yet. Fortunately or not, it means I need to keep proving everything for myself. Wish I had a copy of the Elephant :) | |
| Feb 12, 2018 at 23:32 | comment | added | Mike Shulman | Haha, I forgot that that page existed or I would have linked to it. It looks like I also misremembered the definition; I don't think equalizers are implied by just pullbacks and the rest, you need to assume them too. | |
| Feb 12, 2018 at 23:31 | history | edited | Mike Shulman | CC BY-SA 3.0 |
fix definition of locally regular category, add link
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| Feb 12, 2018 at 22:48 | vote | accept | Tyler Bryson | ||
| Feb 12, 2018 at 22:48 | comment | added | Tyler Bryson | Thanks @mike-shulman. I see you had a hand in writing the relevant nlab locally regular category. Is the definition in your answer here equivalent to that given there? Specifically, are there equalizers in a category with stable reg. epi/mono factorization and pullbacks? Side note: pullbacks + reg. epi/mono factorization (not necessarily stable) $\implies$ reg. epi = strong epi = extremal epi. so the extremal epi/mono factorization will be reg. epi/mono already. | |
| Feb 12, 2018 at 22:17 | history | answered | Mike Shulman | CC BY-SA 3.0 |