Alexander Zass

Doktorand

Kontakt
Raum:
2.09.1.08
Telefon:
+49 331 977-1276


I am a PhD student at the University of Potsdam, under the supervision of  Prof. Dr. Sylvie Roelly  and  Prof. Dr. Gilles Blanchard.

I am a fellow of the Graduate Program SFB 1294 where, together with my supervisors and Dr. Pierre Houdebert , I work in Project A05:  Combining non parametric statistical and probabilistic approaches for inference on cloud-of-points data.

I completed my Master's degree in Padua at Università degli Studi di Padova, with a thesis on “Collective motion of living organisms: the Vicsek model”, and my advisor was Prof. Paolo Dai Pra.

I am proficient in Italian and English, and have a basic knowledge of French.

 

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Publications

2020 | An explicit continuum Dobrushin uniqueness criterion for Gibbs point processes with non-negative pair potentials | Pierre Houdebert, Alexander Zass Link zum Preprint

An explicit continuum Dobrushin uniqueness criterion for Gibbs point processes with non-negative pair potentials

Autoren: Pierre Houdebert, Alexander Zass (2020)

We present a uniqueness result for Gibbs point processes with interactions that come from a non-negative pair potential; in particular, we provide an explicit uniqueness region in terms of activity z and inverse temperature β. The technique used relies on applying to the continuous setting the classical Dobrushin criterion. We also present a comparison to the two other uniqueness methods of cluster expansion and disagreement percolation, which can also be applied for this type of interactions.

2020 | A Gibbs point process of diffusions: existence and uniqueness | Alexander Zass Zeitschrift: Lectures in Pure and Applied Mathematics Verlag: Potsdam University Press Buchtitel: Proceedings of the XI international conference Stochastic and Analytic Methods in Mathematical Physics Seiten: 13-22 Band: 6 Link zur Publikation, Link zum Preprint

A Gibbs point process of diffusions: existence and uniqueness

Autoren: Alexander Zass (2020)

In this work we consider a system of infinitely many interacting diffusions as a marked Gibbs point process. With this perspective, we show, for a large class of stable and regular interactions, existence and (conjecture) uniqueness of an infinite-volume Gibbs process. In order to prove existence we use the specific entropy as a tightness tool. For the uniqueness problem, we use cluster expansion to prove a Ruelle bound, and conjecture how this would lead to the uniqueness of the Gibbs process as solution of the Kirkwood-Salsburg equation.

Zeitschrift:
Lectures in Pure and Applied Mathematics
Verlag:
Potsdam University Press
Buchtitel:
Proceedings of the XI international conference Stochastic and Analytic Methods in Mathematical Physics
Seiten:
13-22
Band:
6

2020 | Marked Gibbs point processes with unbounded interaction: an existence result | Sylvie Roelly, Alexander Zass Zeitschrift: Journal of Statistical Physics Seiten: 972–996 Band: 179 Link zur Publikation, Link zum Preprint

Marked Gibbs point processes with unbounded interaction: an existence result

Autoren: Sylvie Roelly, Alexander Zass (2020)

We construct marked Gibbs point processes in Rd under quite general assumptions. Firstly, we allow for interaction functionals that may be unbounded and whose range is not assumed to be uniformly bounded. Indeed, our typical interaction admits an as finite but random range. Secondly, the random marks - attached to the locations in Rd - belong to a general normed space S. They are not bounded, but their law should admit a super-exponential moment. The approach used here relies on the so-called entropy method and large-deviation tools in order to prove tightness of a family of finite-volume Gibbs point processes. An application to infinite-dimensional interacting diffusions is also presented.

Zeitschrift:
Journal of Statistical Physics
Seiten:
972–996
Band:
179

Teaching