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2 votes
0 answers
62 views

Maximum distance between consecutive terms in sequence with arbitrarily long APs

Good evening. I am writing a paper on complex analysis, and as a corollary (of my work and others'), I believe that I have managed to deduce the following result. Proposition: Let $n_1 < n_2 \cdots ...
0 votes
0 answers
125 views

An exercise about sum-product estimate

I am struggling with 1.11 exercise from the George Shakan "Discrete Fourier Transform". Let $A \subset \mathbb{Z}/q\mathbb{Z}$ be any set not containing zero with $|A|>\sqrt2q^{5/8}$. ...
5 votes
0 answers
215 views

Showing that Fourier pseudorandomness is insufficient for $k=4$ case (four arithmetic progressions)

I wish to show that the Fourier pseudorandomness is insufficient to count the number of 4-term arithmetic progression. Let $A \subset \mathbb{Z}/N\mathbb{Z}$ be a subset of a cyclic group $\mathbb{Z}/...
24 votes
4 answers
3k views

What is the shortest route to Roth's theorem?

Roth first proved that any subset of the integers with positive density contains a three term arithmetic progression in 1953. Since then, many other proofs have emerged (I can think of eight off the ...
3 votes
1 answer
183 views

Some sums related to a quadratic polynomial over $\mathbb{F}_2^n$

For any $c \in \mathbb{F}_2^n$ define $\sigma_c: \mathbb{F}_2^n \to \mathbb{F}_2$ the quadratic polynomial defined for $v = (v_1,v_2,...,v_n)$ by: $$ \sigma_c (v) = \sum_{i=1}^n v_iv_{i+1} + c_iv_i $...