A Refinement of Pohst's Inequality

Abstract

We generalize an inequality conjectured by Pohst in 1977 and recently proved by the author and independently by Battistoni and Molteni. This new inequality improves a bound for the regulator in terms of the discriminant for totally real number fields by taking into account the signs of conjugates of the fundamental unit. We give a new interpretation to the problem and exploit the combinatorial method used by Pohst.