30 citations · 125 across the 40 of their papers we have counts for
8 papers · 1 filter
Optimal Regularity for the parabolic No-Sign Obstacle Problem
John Andersson, Erik Lindgren, Henrik Shahgholian
We study the parabolic free boundary problem of obstacle type $$ \lap u-\frac{\partial u}{\partial t}= fχ_{u\ne 0}. $$ Under the condition that for some function with bo…
On generalized Hardy classes of Dirichlet series
Johan Andersson
We generalize the Hardy class H^2 of Dirichlet series studied by Hedenmalm, Lindqvist, Olofsson, Olsen, Saksman, Seip and others to consider more general Dirichlet series. We prove…
On a problem of Ramachandra and approximation of functions by Dirichlet polynomials with bounded coefficients
Johan Andersson
We prove effective results on when a function can be approximated by a Dirichlet polynomial with bounded coefficients. Assuming that Φ(n) is an increasing function we prove that th…
On the zeta function on the line Re(s) = 1
Johan Andersson
We show the estimates \inf_T \int_T^{T+δ} |ζ(1+it)|^{-1} dt =e^{-γ}/4 δ^2+ O(δ^4) and \inf_T \int_T^{T+δ} |ζ(1+it)| dt =e^{-γ} π^2/24 δ^2+ O(δ^4) as well as corresponding results f…
The Singular Set of Higher Dimensional Unstable Obstacle Type Problems
John Andersson, Henrik Shahgholian, Georg Weiss
In this paper we will investigate the singular points of the following unstable free boundary problem: {equation}\label{Eq} Δu= -χ_{\{u>0\}} \quad\quad\textrm{in} B_1(0) {equation}…
Non universality on the critical line
Johan Andersson
We prove that the Riemann zeta-function is not universal on the critical line by using the fact that the Hardy Z-function is real, and some elementary considerations. This is a rel…