On lower bounds of the density of Delone sets and holes in sequences of sphere packings.
For a fixed integer , and fixed we considerwhere is the error term in the above asymptotic formula. Hitherto the sharpest bounds for are derived in the range min . We also obtain new mean value results for the zeta-function of holomorphic cusp forms and the Rankin-Selberg series.
Galois extensions with various metacyclic Galois groups are constructed by means of a Kummer theory arising from an isogeny of certain algebraic tori. In particular, our method enables us to construct algebraic tori parameterizing metacyclic extensions.