Seminar

The seminar of OBELIX team is currently held on thursdays 11:30 am, every two weeks, at the IRISA lab, Tohannic campus, room D106 (bat. ENSIBS). Usually, the presentation lasts 30 min and is followed by a discussion with the team.

The seminar is coordinated by Chloé Friguet.

Previous seminars

2019  2019-20 2020-21

Upcoming seminars (2020-2021)


  • Date: October, 23 (FRIDAY)
  • Time: 9h30-17h00
  • Room :  A105-107
  • Title: Seminaire au vert! (Annual team seminar)
  • Program here

  • Date: November, 5
  • Time:
  • Room :
  • Speaker: Titouan Vayer (OBELIX, IRISA Vannes) – PhD Defense
  • Title: A contribution to Optimal Transport on incomparable spaces
  • Abstract: Optimal Transport is a theory that allows to define geometrical notions of distance between probability distributions and to find correspondences, relationships, between sets of points. Many machine learning applications are derived from this theory, at the frontier between mathematics and optimization. This thesis proposes to study the complex scenario in which the different data belong to \emph{incomparable} spaces. In particular we address the following questions: how to define and apply the optimal transport between graphs, between structured data? How can it be adapted when the data are varied and not embedded in the same metric space? This thesis proposes a set of Optimal Transport tools for these different cases. An important part is notably devoted to the study of the Gromov-Wasserstein distance whose properties allow to define interesting transport problems on incomparable spaces. More broadly, we analyze the mathematical properties of the various proposed tools, we establish algorithmic solutions to compute them and we study their applicability in numerous machine learning \emph{scenarii} which cover, in particular, classification, simplification, partitioning of structured data, as well as heterogeneous domain adaptation.

  • Date: November, 12
  • Time: 11:30
  • Room :
  • Speaker:Yann Soulard (MCF LETG Rennes)
  • Title:
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  • Date: November, 21 (FRIDAY) // joint seminar with Copernicus Master in Digital Earth
  • Time: 11:30
  • Room :
  • Speaker: Dimitri Lague (CNRS, Géosciences, Rennes)
  • Title:
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  • Date: November, 25 (WEDNESDAY) // joint seminar with Copernicus Master in Digital Earth
  • Time: 11:30
  • Room :
  • Speaker: Thomas Huet ()
  • Title:
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  • Date: November, 26
  • Time: 11:30
  • Room :
  • Speaker: Jeremy Cohen (CR PANAMA, IRISA Rennes)
  • Title: Learning with Low Rank Approximations
  • Abstract: Matrix and tensor factorizations are widespread techniques to extract structure out of data in a potentially blind manner. However, several issues may be raised: (i) these models have often been designed for blind scenarios whereas many applications now features extensive training databases, (ii) their output may not be interpretable because of the lack of identifiability of the parameters and (iii) computing a good solution can be difficult. In this talk, after describing the link between separable functions and tensor/matrix factorizations, we will show that separability and low rank approximations are actually already at the core of many machine learning problems such as dictionary learning or simultaneous factorizations.

  • Date: December, 1 (TUESDAY) // joint seminar with Copernicus Master in Digital Earth
  • Time: 11:30
  • Room :
  • Speaker: Antoine Colin ()
  • Title:
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  • Date: December, 3 (THURSDAY) // joint seminar with Copernicus Master in Digital Earth
  • Time: 11:30
  • Room :
  • Speaker: Damien Arvor ()
  • Title:
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  • Date: December, 4
  • Time:
  • Room : RENNES 2
  • Speaker: Romain Tavenard (LETG Rennes & OBELIX, IRISA) – HDR Defense
  • Title:  Apprentissage statistique et séries temporelles
  • Abstract:

  • Date: December, 16 (WEDNESDAY) // joint seminar with Copernicus Master in Digital Earth
  • Time: 11:30
  • Room :
  • Speaker: Ronan Fablet (LabsTICC, IMT Atlantique, Brest)
  • Title:
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