Talk:Introduction to Category Theory/Products and Coproducts

Did you read next lesson 'products are limits' before you wrote alternate definition? You may want to merge it there. By the way nice work... Tlep 21:19, 11 November 2007 (UTC)

Thanks! I looked at the products are limits section, but it seemed a bit harder than the level I was aiming at; so I decided to go ahead with the putatively easier version here and integrate when I get to that section. The solicitation for comments is supposed to help tell if it makes sense to put anything like that here rather than just later. I think I'll stop fiddling with this section for now so we won't be making uncoordinated and overlapping changes, which already seems to have happened a bit with finite products. AveryAndrews 21:41, 11 November 2007 (UTC)

The very beginning of the products are limits section seems OK in terms of difficulty level - maybe easier than what I wrote due to having more of the details filled in, but I'm not so sure about the organization of the whole thing. In particular, I'm wondering if the material on functors and nat trans shouldn't be pulled out of the next section into one or even two sections of its own. Then there's the problem of how to order that material with the basics of equalizers and limits, etc. One of the problems I find with elementary CT expositions is that there seem to be about five different kinds of 'rudiments' that you have to grasp, without much of any consensus on the best order of presentation, and a general impression left in my learner's mind of a big pile of stuff without much of an idea about what the individual bits are for.

Maybe put the first (on products specifically) section of the next lesson into the hints and details of this lesson, and reorganize the rest? Will have to think about that some more.

AveryAndrews 16:55, 12 November 2007 (UTC)

I reorganized 'products are limits'. Nothing formal on natural transformations any more, and limits are only mentioned in a 'preview'. I hope it is easier now. The page name should be changed to something like 'product functors'. Tlep 15:35, 13 November 2007 (UTC)

Hopefully reemerging from jetlag fog again, I think I still think that there should be a more extensive treatment of functors before this section. AveryAndrews 22:02, 18 November 2007 (UTC)

Started in on the next section. One thing that's annoying me is the apparent absence in the sources I've consulted of an elementary and precise definition of exactly what a universal property is supposed to me -- the acounts given seem to be basically ostensive. So maybe there are no such definitions, or I've looked in the wrong places, or failed to recognize one for what it was.

AveryAndrews 05:52, 22 November 2007 (UTC)

Read here about essentially algebraic definition of products. This should be added to our book. 84.229.199.77 09:50, 24 July 2012 (UTC)

Dead link
Hi,at the end of the "Alternative Definition" section, there is a dead link: http://www.j-paine.org/cgi-bin/webcats/webcats.php. Could you update it, please?


 * ✅ -- Dave Braunschweig (discuss • contribs) 04:33, 13 October 2018 (UTC)