- This is a very broad subject. The problem of deciding how to map a program with arbitrarily many variables onto a fixed set of registers is known as register allocation, and it has been the subject of much research, study, and engineering effort since the very earliest compilers. One of the canonical approaches, graph coloring, was first proposed in 1981. Countless other approaches and variants have been explored since then, and I cannot hope to cover the full breadth of the topic in a single answer.
- Riemann hypothesis (Wikipedia)
In mathematics, the Riemann hypothesis is the conjecture that the Riemann zeta function has its zeros only at the negative even integers and complex numbers with real part 1/2. Many consider it to be the most important unsolved problem in pure mathematics. It is of great interest in number theory because it implies results about the distribution of prime numbers. It was proposed by Bernhard Riemann (1859), after whom it is named.