Binary quadratic forms and sums of triangular numbers
Let , with a positive integer, be a pure cubic number field. We show that the elements whose squares have the form for rational numbers form a group isomorphic to the group of rational points on the elliptic curve . This result will allow us to construct unramified quadratic extensions of pure cubic number fields .
A bibliography of recent papers on lower bounds for discriminants of number fields and related topics is presented. Some of the main methods, results, and open problems are discussed.
Let be an odd prime and a cyclic -extension of number fields. We give a lower bound for the order of the kernel and cokernel of the natural extension map between the even étale -groups of the ring of -integers of , where is a finite set of primes containing those which are -adic.