The size of subset of {1,…,N} without distinct degree polynomial progressions is O(N/(log log N)^c)

You need to know: Polynomial, degree of a polynomial, notation {\mathbb Z}[y] for the set of polynomials in 1 variable with integer coefficients, notation [N] for the set \{1,2,\dots,N\}

Background: Let P=(P_1, \dots, P_m) be a finite set of polynomials P_i \in {\mathbb Z}[y]. For integer N>0, let r_P(N) be the size of the largest subset of [N] containing no subset of the form x, x+P_1(y), \dots, x+P_m(y) with y\neq 0.

The Theorem: On 1st September 2019, Sarah Peluse submitted to arxiv a paper in which she proved that if all polynomials P_i in P have distinct degrees and zero constant terms, then there exists a constant c depending on P_1, \dots, P_m such that
r_P(N) \leq \frac{N}{(\log\log N)^c}.

Short context: Let r_k(N) be the cardinality of the largest subset of [N] which contains no nontrivial k-term arithmetic progressions. Famous Szemerédi’s theorem states that \lim\limits_{N\to\infty}\frac{r_k(N)}{N}=0. In 2000, Gowers proved an explicit bound r_k(N) < N(\log\log N)^{-c} for some constant c=c(k)>0. In 1996, Bergelson and Leibman extended Szemerédi’s theorem to polynomial progressions and proved that \lim\limits_{N\to\infty} \frac{r_P(N)}{N} = 0, if polynomials P_i all have zero constant terms. The Theorem establishes an explicit upper bound on r_P(N), provided that all polynomials P_i have distinct degrees.

Links: Free arxiv version of the original paper is here, journal version is here.

Go to the list of all theorems

Leave a comment