Published online by Cambridge University Press: 05 February 2016
An important result of Weyl states that for every sequence $(a_{n})_{n\geqslant 1}$ of distinct positive integers the sequence of fractional parts of
$(a_{n}{\it\alpha})_{n\geqslant 1}$ is uniformly distributed modulo one for almost all
${\it\alpha}$. However, in general it is a very hard problem to calculate the precise order of convergence of the discrepancy of
$(\{a_{n}{\it\alpha}\})_{n\geqslant 1}$ for almost all
${\it\alpha}$. In particular, it is very difficult to give sharp lower bounds for the speed of convergence. Until now this was only carried out for lacunary sequences
$(a_{n})_{n\geqslant 1}$ and for some special cases such as the Kronecker sequence
$(\{n{\it\alpha}\})_{n\geqslant 1}$ or the sequence
$(\{n^{2}{\it\alpha}\})_{n\geqslant 1}$. In the present paper we answer the question for a large class of sequences
$(a_{n})_{n\geqslant 1}$ including as a special case all polynomials
$a_{n}=P(n)$ with
$P\in \mathbb{Z}[x]$ of degree at least 2.