On indefinite quadratic forms in four variables
We study integral similitude 3 × 3-matrices and those positive integers which occur as products of their row elements, when matrices are symmetric with the same numbers in each row. It turns out that integers for which nontrivial matrices of this type exist define elliptic curves of nonzero rank and are closely related to generalized cubic Fermat equations.
This paper is concerned with non-trivial solvability in -adic integers of systems of additive forms. Assuming that the congruence equation has a solution with we have proved that any system of additive forms of degree with at least variables, has always non-trivial -adic solutions, provided . The assumption of the solubility of the above congruence equation is guaranteed, for example, if .