We study the notion of reverse hypercontractivity. We show that reverse
hypercontractive inequalities are implied by standard hypercontractive
inequalities as well as by the modified log-Sobolev inequality. Our proof is
based on a new comparison lemma for Dirichlet forms and an extension of the
Strook-Varapolos inequality.
We study properties of the signature function of the torus knot $T_{p,q}$.
First we provide a very elementary proof of the formula for the integral of the
signatures over the circle. We obtain also a closed formula for the
Tristram--Levine signature of a torus knot in terms of Dedekind sums.