  We show that the neutron star minimum period of rotation is determined, for
causal equations of state, by the maximum value of the relativistic
(compactness) parameter 2GM/Rc^2, allowed by causality for static neutron
stars, 0.7081, and by the largest measured mass of a neutron star. The relation
between these three quantities, resulting from the extrapolation of the
empirical formulae of Lasota et al. (1996), yields the minimum period of 0.288
ms, only 2% higher than an absolute lower bound obtained in extensive exact
numerical calculations of Koranda et al. (1997).
