Ruzsa's conjecture on spanning size in abelian groups of finite torsion

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Let GG be an abelian group with finite torsion rr, and let AA be a finite subset of GG. Write A+A={a+b∣a,b∈A}A+A=\{a+b\mid a,b\in A\} and let ⟨A⟩\langle A\rangle be the smallest subgroup or coset of a subgroup containing AA. The doubling constant is ∣A+A∣/∣A∣|A+A|/|A|.

Ruzsa's conjecture. If there exists a constant KK such that

∣A+A∣∣A∣≤K,\frac{|A+A|}{|A|}\leq K,

then there exists a constant C≥2C\geq 2 such that

∣⟨A⟩∣∣A∣≤rCK.\frac{|\langle A\rangle|}{|A|}\leq r^{CK}.

This conjecture predicts that the exponential dependence on the doubling parameter in the Freiman--Ruzsa theorem is essentially optimal, while replacing the theorem's much larger exponent by a linear function of KK. The supplied text gives no resolution status.

References

Primary source

Yifan Jing and Souktik Roy, “Small doublings in abelian groups of prime power torsion”, arXiv:1901.05606 (2019).

Additional references

2 papers in this index state this conjecture (2012–2019). The statement above is taken from the most recent of them; the others are arXiv:1212.5738.

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