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Polynomial dependence on the doubling constant K in algorithmic PFR

Determine whether there exists an algorithm for the algorithmic Polynomial Freiman–Ruzsa tasks whose query and time complexities scale polynomially in the doubling constant K when K grows asymptotically.

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Background

Throughout the paper and much of additive combinatorics, the doubling constant K is typically treated as a fixed constant since constant doubling yields strong structure. The algorithms presented have complexities optimal in n (up to logs) but do not claim polynomial dependence on K when K increases with n.

The authors explicitly highlight improving the dependence on K as an open direction, asking whether one can design algorithms whose complexities are polynomial in K for asymptotically growing K, which would strengthen the practicality of algorithmic PFR in broader regimes.

References

One concrete question that is left open from our work is to improve the dependence on the doubling constant K. As is standard in additive combinatorics, K is assumed to be a constant, but for asymptotically growing K it is an interesting open problem whether there exists an algorithm with query and time complexities that scale polynomially in K.

Algorithmic Polynomial Freiman-Ruzsa Theorems (2509.02338 - Arunachalam et al., 2 Sep 2025) in Introduction, Future directions