There are many different types of numbers, some of which you may remember from school: natural, rational, irrational, imaginary, calculable and incalculable numbers. Today, however, we are going to ...

What is your favorite number? For many people, it may be an irrational number such as pi (π), Euler’s number (e) or the square root of 2. Even among the natural numbers (positive integers), there are ...

Infinite sets $P$ and $Q$ of primes are described, $P \subset Q$. For any natural number $n$ it can be decided if $n \in P$ in (deterministic) time $O((\log n)^9 ...

I construct an example of a graded algebra that is realized as the rational cohomology algebra of exactly n rational homotopy types, for each natural number n. The algebras constructed have trivial ...