A non-convex generalization of the circle problem.
In the problem of (simultaneous) Diophantine approximation in (in the spirit of Hurwitz’s theorem), lower bounds for the critical determinant of the special three-dimensional body play an important role; see [1], [6]. This article deals with estimates from below for the critical determinant of more general star bodies where is any positive constant. These are obtained by inscribing into either a double cone, or an ellipsoid, or a double paraboloid, depending on the size of .
After a brief exposition of the state-of-art of research on the (Euclidean) simultaneous Diophantine approximation constants , new lower bounds are deduced for and .
In a classic paper, W.G. Spohn established the to-date sharpest estimates from below for the simultaneous Diophantine approximation constants for three and more real numbers. As a by-result of his method which used Blichfeldt’s Theorem and the calculus of variations, he derived a bound for the critical determinant of the star body In this little note, after a brief exposition of the basics of the geometry of numbers and its significance for Diophantine approximation, this latter result is improved...