manifold learning [BNP Seminar, 11/01/23]

Posted in Books, Statistics, University life with tags , , , , , , , , on January 9, 2023 by xi'an

An incoming BNP webinar on Zoom by Judith Rousseau and Paul Rosa (U of Oxford), on 11 January at 1700 Greenwich time:

Bayesian nonparametric manifold learning

In high dimensions it is common to assume that the data have a lower dimensional structure. We consider two types of low dimensional structure: in the first part the data is assumed to be concentrated near an unknown low dimensional manifold, in the second case it is assumed to be possibly concentrated on an unknown manifold. In both cases neither the manifold nor the density is known. Atypical example is for noisy observations on an unknown low dimensional manifold.

We first consider a family of Bayesian nonparametric density estimators based on location – scale Gaussian mixture priors and we study the asymptotic properties of the posterior distribution. Our work shows in particular that non conjuguate location-scale Gaussian mixture models can adapt to complex geometries and spatially varying regularity when the density is supported near a low dimensional manifold.

In the second part of the talk we will consider also the case where the distribution is supported on a low dimensional manifold. In this non dominated model,we study different types of posterior contraction rates: Wasserstein and $L_1(\mu_\mathcal{M})$ where $\mu_\mathcal{M}$ is the Haussdorff measure on the manifold $\mathcal{M}$ supporting the density. Some more generic results on Wasserstein contraction rates are also discussed.

CANSSI HSC seminar series

Posted in Statistics, University life with tags , , , , , , , on January 19, 2022 by xi'an

thanks from CIRM

Posted in Statistics with tags , , , , , , , , , , , , , , , , , on July 5, 2021 by xi'an

ISBA 2.1…0!

Posted in Statistics, University life with tags , , , , , , , on June 28, 2021 by xi'an

As the first fully virtual ISBA 2021 meeting is about to start, let me remind participants of the following:

On the Whova Agenda, you can see the Agenda in your local time, be sure to toggle the option. And the list of posters for each of the four poster sessions is available in the Agenda, as well as at the entrance of each poster “room” on gather.town

Reminder for session chairs

• Please monitor Zoom’s Q&A and Zoom’s chat for questions from attendees
• Please monitor the session time and remind the speakers of their time, as the webinar will close after 3 minutes after the end of the session
• Please keep to the planned schedule for each talk in case of a missing speaker or of a speaker unable to join the Zoom platform for connection or technical reasons

Reminder for speakers

Reminder for the remaining 2136 attendees

• The Zoom link for a given session is available by selection this session from Whova Agenda and clicking on “Join the live stream here”
• Please type your questions using Zoom’s Q&A or Zoom’s chat, and specify which speaker’s name you would like to hear the answers from
• Please do not use Whova’s chat for questions
• Contributed sessions are recorded and already available, while invited sessions will be recorded with permission from the speakers

ISBA 2021, one more week but already in the future!

Posted in pictures, Statistics, Travel, University life with tags , , , , , , , , , on June 21, 2021 by xi'an

The main section of the ISBA 2021 (formerly ISBA 2020) conference starts a week from today, with short courses this week, but it is now a futuristic conference in that… the number of registered participants already exceeds the year of the meeting! There are currently 2033 registrations, a quantic leap from the earlier editions (if helped with the virtual nature of the meeting and the absence of any registration fee). Here are the recommendations to be found on the Whova conference portal, just in case:

The ISBA conference will be a mixture of live talks, pre-recorded talks, and posters. All live-streaming will be via Zoom, with links integrated into the Whova platform.

1. Plenary talks (i.e., Foundational Lectures, Keynote Lectures, and Named Lectures) and all invited talks will be live-streamed during the corresponding sessions.
2. Contributed talks are prerecorded (available from June 10, 2021). During the live-streamed Contributed Sessions, each speaker will give a 5-min live recap of their contributed talk,  highlighting the main points, followed by live discussion and Q&A from the audience.
3. Contributed speakers who had optionally chosen to accompany their talk with a poster will present the poster in their designated Poster Sessions. All Poster Sessions will be held on Gather.town, which will also serve as the virtual space for social times during the whole conference.
4. Gather.town is live at https://gather.town/app/QZTh2a4InnLxAvYF/ISBA_WM_2021_main. You should be able to access with the same email used to register for Whova.

And be aware that the schedule page does not contain the links to the prerecorded videos and slides. Make sure to use the webapp link.