On 07 Nov 2008, at 15:57, Mirek Dobsicek wrote:

> > Bruno Marchal in an older post wrote: >>> Also, >>> can you elaborate a bit more on the motivation behind category >>> theory? >>> Why >>> was it invented, and what problems does it solve? What's the >>> relationship >>> between category theory and the idea that all possible universes >>> exists? >> >> >> Tim makes a very genuine remark (but he writes so much I fear that >> has >> been unnoticed!). He said: read Tegmark (Everything paper), then >> learn >> category, then read again Tegmark. Indeed I would say category >> theory has > > Bruno, which of the Tegmark's 'Everything papers' did you have in > your mind? I guess it is this one: http://space.mit.edu/home/tegmark/index.html But it looks the paper is alive and evolves. I was thinking of its diagram of mathematical structures. Category theory put "natural" order in mathematical theories. But recursion theory is a sort of obstacle. category theory works well for sort of first person recursion theory (like with realizability, typed lambda calculus/comobinators, etc.) Then category is a must for knots and geometry ... Well come back, Bruno http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [EMAIL PROTECTED] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---