# Talk:To Do List

### From Mwiki

The porous medium equation is technically a quasi-linear equation. There is now a page about semilinear equations to clarify the issue.

I see, by the way, how come Navier-Stokes is semilinear then? I was sure it was quasi until now.

---> It is the heat equation plus a first order nonlinear term.

## Contents |

## Main page vs no Main page?

What is currently the "Main page" should become the "Community portal", and we can use the Main page as the starting page. What do you guys think? -Nestor.

- Right now I don't have an opinion either for or against. (Luis 11:03, 5 June 2011 (CDT))

I also started playing around with the use of categories (see the "Quasilinear equations" category)

## Let us try to avoid a big bias

I was talking to Russell today that we have to make an effort not to have a strong bias towards Caffarelli related stuff. Otherwise, the purpose of the wiki will fail. (Luis 00:58, 8 June 2011 (CDT))

Indeed! I think so far we don't have to worry about it since we are just getting started with the pages (naturally we will write first stuff we know best). I hope it won't become a problem. Also, having Moritz will help a lot too. (Nestor) (5:42 pm US Eastern Time, 8 June 2011)

## Classical potential analysis

I removed this comment from the page because I believe it belongs to the discussion. (Luis 20:11, 8 June 2011 (CDT))

- Luis C. would be very disappointed if we did not even mention topics from good old potential theory. Very importantly, Riesz potentials and the Poisson kernel for Fractional harmonic functions. Someone better start dusting off their copy of Landkof.

I put some of those topics on the page about the fractional Laplacian.

Yeah, good call on that. I will add more stuff to those articles later (Nestor)

## Physics Lingo: "Strong interactions"

- A reminder for later (to make a full article out of this): it has become clear (although in hindsight it is a tautology) that what physicists call "strong interactions" is the same as "very non-local". Namely, strong interactions correspond to forces that approach infinity much, much faster than say Coulomb's force as the distance between two particles goes to zero, mathematically, this means the interaction kernel $k(x,y)$ goes like $|x-y|^{-\gamma}$ for a very big positive number $\gamma$. (Nestor 21:00, 27 January 2012 (CST))

By the way, this comment is directly related to the email I sent the other day about the supposed role of non-locality in particle physics (Nestor 21:02, 27 January 2012 (CST))