Seminars usually take place either at
UPV/EHU, Seminar Room of the Mathematics Department, Facultad de Ciencias, on Thursdays at 12:00, or
BCAM, Seminar Room, on Thursdays at 17:00.
Some seminars were recorded, and the videos can be found together with the description of the seminar on the subpage related to the year the talk happened. You can also find them here.
To subscribe to the seminar mailing list, contact one of the organizers.
As of June 25th, 2026, the count of talks reached 302.
BCAM, September 17th, 2026, 17:00 - 18:00
The Hausdorff dimension of sets containing circles or line segments in many directions.
Antonio Córdoba - Universidad Autónoma de Madrid
We establish a lower bound for the Hausdorff dimension of a set K ⊂ ℝⁿ that contains a translated copy of every meridian, that is, of every (d − 2)-dimensional sphere passing through the poles of 𝕊ᵈ⁻¹, a (d − 1)-dimensional sphere, with 3 ≤ d ≤ n, and 𝕊ᵈ⁻¹ ⊂ ℝⁿ.
Under this assumption, we have
dimₕ(K) ≥ d − 1.
This result is closely related to, and reminiscent of, the classical Kakeya set problem. We build upon this connection, employing similar techniques to show that if K ⊂ ℝᵈ contains a unit straight line segment in every direction corresponding to a smooth curve on 𝕊ᵈ⁻¹, then its Hausdorff dimension is ≥ 2.
EHU, October 1st, 2026, 12:00 - 13:00
Long-wave instability of periodic shear flows with constant magnetic field for the 2D resistive MHD equations.
Claudia Peña - BCAM
The purpose of this talk is to present the article [1] in which we establish two results:
On the one hand, we study the long-wave linear (in)stability of the two-dimensional viscous, resistive Magnetohydrodynamic (MHD) equations on the periodic domain T_\alpha × T = R/(2π\alpha Z) × R/(2πZ) in the regime α ≪ 1, around a periodic shear flow (U(y), 0) coupled with a constant background magnetic field b = (b1, b2). It is a non-trivial extension of the recent paper [2] for the Navier-Stokes equations to the MHD setting.
On the other hand, as a dynamical consequence of the spectral analysis carried out along the proof, we obtain a splitting of the phase space into unstable and stable subspaces, on which solutions grow or decay exponentially in Sobolev norm.
[1] Feola, R., Franzoi, L., Montalto, R., Peña, C. Long-wave instability of periodic shear flows with constant magnetic field for the 2D resistive MHD equations. arXiv:2607.25836.
[2] Colombo, M., Dolce, M., Montalto, R. and Ventura, P.: Long-wave instability of periodic shear flows for the 2D Navier-Stokes equations. arXiv:2509.18070.
BCAM, October 8th, 2026, 17:00 - 18:00
Hanifah Mumtaz - University of Regensburg
TBA
EHU, October 29th, 2026, 12:00 - 13:00
Ruting Wang
TBA