On counterexamples to the Mertens conjecture
Seungki Kim, Phong Q. Nguyen
TL;DR
This paper refines the upper bound on the smallest counterexample to the Mertens conjecture by applying state-of-the-art lattice point enumeration to an optimized, unbalanced lattice that encodes the Diophantine approximation underlying the Mertens problem. By replacing extensive LLL-based trials with pruned lattice enumeration, and by carefully tuning lattice parameters, the authors obtain $\mathfrak x<\exp(1.96\times 10^{19})$, a dramatic improvement over prior bounds and well below certain growth conjectures. The work clarifies practical implementation details (BKZ/Lattice reduction, pruning strategies, and high-precision zeta-zero data) and demonstrates robust sanity checks and potential extensions to related questions about $M(x)$ and the zeta-zero distribution. It also outlines several directions for future research, including further reductions of $\mathfrak x$, insights into the growth of $q(x)$, and implications for linear relations among zeta zeros, highlighting the continued relevance of lattice techniques in analytic number theory.
Abstract
We use state-of-art lattice algorithms to improve the upper bound on the lowest counterexample to the Mertens conjecture to $\approx \exp(1.96 \times 10^{19})$, which is significantly below the conjectured value of $\approx \exp(5.15 \times 10^{23})$ by Kotnik and van de Lune [KvdL04].
