You need to know: Prime factorisation of positive integers, limits.
Background: For a positive integer n, let be the number of prime factors of n, counted with multiplicity. Function
is known as the Liouville function. The block complexity
of
is the number of sign patterns of size n that are taken by consecutive values of
.
The Theorem: On 2nd August 2017, Nikos Frantzikinakis and Bernard Host submitted to arxiv a paper in which they proved, among other results, that .
Short context: The Chowla conjecture predicts, as one may naturally expect, that all possible sign patterns of size n are taken by the Liouville function. In other words, is conjectured to be
. However, the best lower bound for
before 2017 was only
for
. The Theorem significantly improves this bound.
Links: Free arxiv version of the original paper is here, journal version is here.