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Séminaire MODAL'X : Julien Poisat (CEREMADE, Université Paris-Dauphine)

Publié le 13 octobre 2023 Mis à jour le 13 octobre 2023

The simple random walk conditioned to visit atypically few sites in dimension three and higher.


le 7 décembre 2023


Bâtiment Maurice Allais (G)

Bâtiment Allais (G), salle Modal'X
Plan d'accès
Abstract: we consider the simple random walk on the Euclidean lattice in transient dimensions. It is known that the number of distinct visited sites is asymptotically linear in time. The probability of visiting a smaller number of sites, with a difference of the order of the mean, was evaluated asymptotically by Phetpradap in 2010, taking up the seminal work of van den Berg, Bolthausen and den Hollander in 2001 concerning the volume of a Wiener sausage. We consider the random walk conditioned to such a rare event and prove that the occupation measure of a certain random walk skeleton converges to a unique optimal profile modulo space shift, provided the deviation from the mean is large enough if dimension is four or higher. Our proof of this so-called tube property relies on the recent compactification of the space of measures introduced by Mukherjee and Varadhan, and it is a first step in the rigourous proof of the Swiss cheese picture proposed by van den Berg, Bolthausen and den Hollander. This is joint work with Dirk Erhard (Salvador de Bahia, Brazil).

Mis à jour le 13 octobre 2023