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# Classical metric Diophantine approximation revisited: the Khintchine-Groshev theorem

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 Title Classical metric Diophantine approximation revisited: the Khintchine-Groshev theorem Publication Type Journal Article Year of Publication 2010 Authors Beresnevich V, Velani S Refereed Designation Refereed Journal Int. Math. Res. Not. Volume 2010, no.1 Pagination 69-86 Abstract Under the assumption that the approximating function $\psi$ is monotonic, the classical Khintchine-Groshev theorem provides an elegant probabilistic criterion for the Lebesgue measure of the set of $\psi$-approximable matrices in $\mathbb{R}^{mn}$. The famous Duffin-Schaeffer counterexample shows that the monotonicity assumption on $\psi$ is absolutely necessary when $m=n=1$. On the other hand, it is known that monotonicity is not necessary when $n > 2$ (Sprindzuk) or when $n=1$ and $m>1$ (Gallagher). Surprisingly, when $n=2$ the situation is unresolved. We deal with this remaining case and thereby remove all unnecessary conditions from the classical Khintchine-Groshev theorem. This settles a multi-dimensional analogue of Catlin's Conjecture. URL http://arxiv.org/abs/0811.0809 E-print number arXiv:0811.0809