Monthly Archives: November 2013

Additive vs multiplicative densities

It is basic fact of measure theory that there is no uniform measure on a countable set such as the set of all natural numbers. However, there are many ways to measure size of subsets of . For instance, the … Continue reading

Posted in Combinatorics | Tagged , , , , | 1 Comment

Primes of the form x^2+2y^2

In this post I will present a quite nice proof of the following fact from elementary number theory: Theorem 1 Let be a prime number. There are such that if and only if is a quadratic residue . Recall that … Continue reading

Posted in Classic results, Number Theory | Tagged , , | Leave a comment