1. A strengthening of Freiman's 3k−4$3k-4$ theorem.
- Author
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Bollobás, Béla, Leader, Imre, and Tiba, Marius
- Subjects
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ARITHMETIC series - Abstract
In its usual form, Freiman's 3k−4$3k-4$ theorem states that if A$A$ and B$B$ are subsets of Z${\mathbb {Z}}$ of size k$k$ with small sumset (of size close to 2k$2k$), then they are very close to arithmetic progressions. Our aim in this paper is to strengthen this by allowing only a bounded number of possible summands from one of the sets. We show that if A$A$ and B$B$ are subsets of Z${\mathbb {Z}}$ of size k$k$ such that for any four‐element subset X$X$ of B$B$ the sumset A+X$A+X$ has size not much more than 2k$2k$, then already this implies that A$A$ and B$B$ are very close to arithmetic progressions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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