Ciro Santilli @cirosantilli 37

4 squares are sufficient by Lagrange's four-square theorem.

3 is not enough by Legendre's three-square theorem.

The subsets reachable with 2 and 3 squares are fully characterized by Legendre's three-square theorem.

Complexity: NP-intermediate as of 2020:

The basis of RSA: RSA. But not proved NP-complete, which leads to:

I think these are the ones where $\Delta H\times \Delta S>0$, i.e. enthalpy and entropy push the reaction in different directions. And so we can use temperature to move the Chemical equilibrium back and forward.

The problem with a single-level paging scheme is that it would take up too much RAM: 4G / 4K = 1M entries per process.

If each entry is 4 bytes long, that would make 4M per process, which is too much even for a desktop computer: ps -A | wc -l says that I am running 244 processes right now, so that would take around 1GB of my RAM!

For this reason, x86 developers decided to use a multi-level scheme that reduces RAM usage.

The downside of this system is that is has a slightly higher access time, as we need to access RAM more times for each translation.

archive.org/details/quantumstoryhist0000bagg on the Internet Archive Open Library.

Ciro Santilli's LinkedIn profile: www.linkedin.com/in/cirosantilli/ see also: accounts controlled by Ciro Accounts.

LinkedIn fully complies with censorship imposed locally by the Chinese government, and does so in a non-transparent way: cirosantilli.com/china-dictatorship/linkedin.

It is hard to understand what the point of that website is, as it is basically just a more closed version of Facebook, but alas, it has flourished as the only place where people post more useful content compared to Twitter and Facebook. In any case, Ciro just applies the same unfollow policy to all of them: aggressively filter your social media follows.

The first really good quantum mechanics theory made compatible with special relativity was the Dirac equation.

And then came quantum electrodynamics to improve it: Dirac equation vs quantum electrodynamics.

TODO: does it use full blown QED, or just something intermediate?

www.youtube.com/watch?v=NtnsHtYYKf0 "Mercury and Relativity - Periodic Table of Videos" by Periodic Videos (2013). Doesn't give the key juicy details/intuition. Also mentioned on Wikipedia: en.wikipedia.org/wiki/Relativistic_quantum_chemistry#Mercury