%0 Journal Article %T Comparison between lower and upper $ \alpha-$densities and lower and upper $ \alpha-$analytic densities %A Rita Giuliano Antonini %A Georges Grekos %J Uniform Distribution Theory %D 2008 %I Mathematical Institute of the Slovak Academy of Sciences %X Let $\alpha$ be a real number, with $\alpha \geq - 1$. We prove a general inequality between the upper (resp. lower) $\alpha-$analytic density and the upper (resp. lower)$\alpha-$density of a subset $A$ of $\mathbb N^*$ (Proposition 2.1). Moreover, we prove by an example that the upper and the lower $\alpha$--densities and the lower and upper $\alpha$--analytic densities of $A$ do not coincide in general ({\it i.e.}, the inequalities proved in (2.1) may be strict). On the other hand, we identify a class of subsets of $\mathbb N^*$ for which these values do coincide in the case $\alpha > -1$. %K $\ %K alpha-$density %K $\ %K alpha-$analytic density %K logarithmic density %K analytic density %K tauberian theorem %K slowly varying function %K regular set %U http://www.boku.ac.at/MATH/udt/vol03/no2/GiuGr08-2.pdf