* Dates within the next 7 days are marked by a star.
Gerardo Barrera (IST Lisbon)
Cutoff phenomenon for the ergodic CIR process and extensions
* Tuesday 04 February 2025, 10:15, M3 (M234)
In this talk we investigate the convergence to equilibrium as the noise intensity $\epsilon$ tends to zero for ergodic random systems out of equilibrium driven by multiplicative non-linear noise of the following type
\[
d X^{\epsilon}_t(x)=(b-aX^{\epsilon}_t(x))dt+\epsilon \sqrt{X^{\epsilon}_t(x)}dB_t,\quad X_0=x,
\]
where $x>0$, $a>0$ and $b>0$ are constants, and $(B_t)_{t>0}$ is a one-dimensional standard Brownian motion. More precisely, we establish the occurrence of the so-called profile cutoff phenomenon in the total variation distance and in the renormalized Wasserstein distance when the intensity of the noise tends to zero. Our results include explicit cut-off time, explicit time window, and explicit profile function. Furthermore, asymptotics of the so-called mixing times are given explicitly. This is based in the paper https://arxiv.org/pdf/2402.15457 with Liliana Esquivel, Universidad de Puerto Rico, Puerto Rico.
Michal Borowski (University of Warsaw)
Approximation in variational problems
* Wednesday 05 February 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Jaakko Takala (Aalto)
Diplomityöesitelmä: Wizard's 21 -pelin optimaalinen pelistrategia
* Thursday 06 February 2025, 13:00, Y405
Martti Ranta: Diplomityöesitelmä
TBA
* Thursday 06 February 2025, 14:15, M2 (M233)
Diplomityöesitelmä / Hakula
Sami Vihko (University of Helsinki)
TBA
Tuesday 11 February 2025, 10:15, M3 (M234)
Ioana Ciotir (INSA Rouen, Normandie Université)
Stochastic porous media equation with Robin boundary conditions, gravity-driven infiltration and multiplicative noise
Wednesday 12 February 2025, 10:15, M3 (M234)
We aim at studying a novel mathematical model associated to a physical phenomenon of infiltration in an homogeneous porous medium. The particularities of our system are connected to the presence of a gravitational acceleration term proportional to the level of saturation, and of a Brownian multiplicative perturbation. Furthermore, the boundary conditions intervene in a Robin manner with the distinction of the behavior along the inflow and outflow respectively. We provide qualitative results of well-posedness, the investigation being conducted through a functional approach.
Joint work with Dan Goreac, Juan Li and Antoine Tonnoir.
Seminar on analysis and geometry
Prof Joni Virta (University of Turku)
Unsupervised linear discrimination using skewness
Wednesday 12 February 2025, 10:15, M237
It is known that, in Gaussian two-group separation, the optimally discriminating projection direction can be estimated without any knowledge on the group labels. In this presentation, we (a) motivate this estimation problem, and (b) gather several unsupervised estimators based on skewness and derive their limiting distributions. As one of our main results, we show that all affine equivariant estimators of the optimal direction have proportional asymptotic covariance matrices, making their comparison straightforward. We use simulations to verify our results and to inspect the finite-sample behaviors of the estimators.
Aalto Stochastics and Statistics Seminar / Leskelä
Prof. Tuomas Hytönen (Aalto University)
Commutators, finite rank approximation, classical and quantum derivatives
Wednesday 12 February 2025, 15:15, A1 (A123)
Quantifying the failure of the commutative law ab = ba for objects beyond numbers is key to diverse topics in pure and applied mathematics. This is achieved by studying the properties of the related commutator. Anything that one might wish to feed to a computer is necessarily finite, and hence it is useful to know how well such commutators can be estimated by finite rank approximations. It turns out that the rate of approximation has a sharp threshold that cannot be beaten, while the best possible approximation rate has connections to both classical differentiability and a certain quantum analogue. A general framework for these questions is contained in my recent work with Riikka Korte.
Lin Wu (Xiamen University/Aalto University)
Uniform weighted bounds for fractional Marcinkiewicz integrals
Wednesday 19 February 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Victor Mishnyakov (Nordita)
TBA
Wednesday 19 February 2025, 10:15, M2 (M233)
Aki Mori (Setsunan University)
TBA
Thursday 20 February 2025, 14:15, M2 (M233)
Algebra & Discrete Mathematics (ADM) Seminar
David Adame-Carrillo (opponent prof. Alessandro Giuliani)
PhD thesis defense: "Lattice models and conformal field theory"
Tuesday 25 February 2025, 13:00, R002/160a R1
Luis Angel Castillo López (Universidad Nacional Autónoma de México)
TBA
Wednesday 26 February 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Kostya Tolmachov (Universität Hamburg)
TBA
Thursday 27 February 2025, 14:15, M2 (M233)
Algebra & Discrete Mathematics (ADM) Seminar
Aleksis Koski
TBA
Wednesday 05 March 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Aapo Pulkkinen
TBA
Wednesday 12 March 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Topias Terho (Aalto University)
Optimization models and solution algorithms for influence diagrams (Midterm review)
Wednesday 12 March 2025, 11:00, M240
Prof. Marcus Greferath (University College Dublin/Aalto)
Some old and new ideas on noiseless and noisy group testing
Wednesday 12 March 2025, 16:15, M3 (M234)
Group Testing is an area in information and communication sciences that is as well-established as Coding Theory and Cryptography. The author of this talk stumbled over this amazingly interesting topic during the recent COVID-19 pandemic and came to the moderately surprising observation that (non-adaptive) group testing in both the noiseless and the noisy (=error-correcting) case, may be considered as coding theory over the Boolean semi-field (1+1=1). Following this path, he discovered new and re-discovered known results of the theory that now allow for a presentation in a new skin. This talk will delve into the topic and show how Noiseless and Noisy Group Testing can be connected to Partially Ordered Sets, Residuation, Partial Linear Spaces, Configurations, Barbilian Spaces, and Block Designs, which gives raise to further applications of Finite Geometry and Order Theory.
ANTA Seminar / Hollanti et al.
Professor Estibalitz Durand Cartagena (UNED, Madrid)
TBA
Wednesday 02 April 2025, 10:15, M3 (M234)
Seminar on analysis and geometry
Hana Ephremidze (Universität Bonn)
TBA
Thursday 03 April 2025, 14:15, M2 (M233)
Algebra & Discrete Mathematics (ADM) Seminar
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