The category of categories as a 3-limit
Hi, In [1], Mike Shulman explains how one can define: * the category of magmas as an inserter in the 2-category of (large) categories, * the category of semigroups as an equifier, * and so on up to the category of rings. Can we go further? What is the 2-categorical limit to be used in order to define the category of small categories? But since small categories form a 2-category, maybe I should reformulate my question: What is the 3-categorical limit to be used in order to define the 2-category of small categories? While I am asking... What is the (n+2)-categorical limit to be used in order to define the (n+1)-category of n-categories? what is the omega-categorical limit to be used in order to define the omega-category of omega-categories? [1] http://mathoverflow.net/questions/9269/category-of-categories-as-a-foundatio... [For admin and other information see: http://www.mta.ca/~cat-dist/ ]
On 28/11/2011, at 11:04 PM, David Leduc wrote:
Can we go further? What is the 2-categorical limit to be used in order to define the category of small categories?
Dear David Back in 1976 I had some notes typed that may be along the lines of what you are after. I just scanned them in and put them at: http://www.maths.mq.edu.au/~street/Sketch.pdf I was going to revise, expand and maybe even correct those notes but never got around to it. It's all pretty well understood by now. If you are happy that you have an object S of sets in your 2-category, this shows how to get an object Cat(S) of categories. Best wishes, Ross [For admin and other information see: http://www.mta.ca/~cat-dist/ ]
participants (2)
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David Leduc -
Ross Street