36 research outputs found
Optimal Transportation Theory with Repulsive Costs
This paper intents to present the state of art and recent developments of the
optimal transportation theory with many marginals for a class of repulsive cost
functions. We introduce some aspects of the Density Functional Theory (DFT)
from a mathematical point of view, and revisit the theory of optimal transport
from its perspective. Moreover, in the last three sections, we describe some
recent and new theoretical and numerical results obtained for the Coulomb cost,
the repulsive harmonic cost and the determinant cost.Comment: Survey for the special volume for RICAM (Special Semester on New
Trends in Calculus of Variations
A Numerical Method to solve Optimal Transport Problems with Coulomb Cost
In this paper, we present a numerical method, based on iterative Bregman
projections, to solve the optimal transport problem with Coulomb cost. This is
related to the strong interaction limit of Density Functional Theory. The first
idea is to introduce an entropic regularization of the Kantorovich formulation
of the Optimal Transport problem. The regularized problem then corresponds to
the projection of a vector on the intersection of the constraints with respect
to the Kullback-Leibler distance. Iterative Bregman projections on each
marginal constraint are explicit which enables us to approximate the optimal
transport plan. We validate the numerical method against analytical test cases
Generalized incompressible flows, multi-marginal transport and Sinkhorn algorithm
Starting from Brenier's relaxed formulation of the incompressible Euler
equation in terms of geodesics in the group of measure-preserving
diffeomorphisms, we propose a numerical method based on Sinkhorn's algorithm
for the entropic regularization of optimal transport. We also make a detailed
comparison of this entropic regularization with the so-called Bredinger
entropic interpolation problem. Numerical results in dimension one and two
illustrate the feasibility of the method
Convergence rate of entropy-regularized multi-marginal optimal transport costs
We investigate the convergence rate of multi-marginal optimal transport costs
that are regularized with the Boltzmann-Shannon entropy, as the noise parameter
tends to . We establish lower and upper bounds on the
difference with the unregularized cost of the form
for some explicit dimensional
constants depending on the marginals and on the ground cost, but not on the
optimal transport plans themselves. Upper bounds are obtained for Lipschitz
costs or locally semi-concave costs for a finer estimate, and lower bounds for
costs satisfying some signature condition on the mixed second
derivatives that may include degenerate costs, thus generalizing results
previously in the two marginals case and for non-degenerate costs. We obtain in
particular matching bounds in some typical situations where the optimal plan is
deterministic
Computation of Cournot-Nash equilibria by entropic regularization
We consider a class of games with continuum of players where equilibria can be obtained by the minimization of a certain functional related to optimal transport as emphasized in [7]. We then use the powerful entropic regularization technique to approximate the problem and solve it numerically in various cases. We also consider the extension to some models with several populations of players
Computation of Cournot-Nash equilibria by entropic regularization
We consider a class of games with continuum of players where equilibria can be obtained by the minimization of a certain functional related to optimal transport as emphasized in [7]. We then use the powerful entropic regularization technique to approximate the problem and solve it numerically in various cases. We also consider the extension to some models with several populations of players
You Can't Hide Behind Your Headset: User Profiling in Augmented and Virtual Reality
Virtual and Augmented Reality (VR, AR) are increasingly gaining traction
thanks to their technical advancement and the need for remote connections,
recently accentuated by the pandemic. Remote surgery, telerobotics, and virtual
offices are only some examples of their successes. As users interact with
VR/AR, they generate extensive behavioral data usually leveraged for measuring
human behavior. However, little is known about how this data can be used for
other purposes.
In this work, we demonstrate the feasibility of user profiling in two
different use-cases of virtual technologies: AR everyday application ()
and VR robot teleoperation (). Specifically, we leverage machine learning
to identify users and infer their individual attributes (i.e., age, gender). By
monitoring users' head, controller, and eye movements, we investigate the ease
of profiling on several tasks (e.g., walking, looking, typing) under different
mental loads. Our contribution gives significant insights into user profiling
in virtual environments
A Numerical Method to solve Optimal Transport Problems with Coulomb Cost
International audienceIn this paper, we present a numerical method, based on iterative Bregman projections, to solve the optimal transport problem with Coulomb cost. This is related to the strong interaction limit of Density Functional Theory. The first idea is to introduce an entropic regularization of the Kantorovich formulation of the Optimal Transport problem. The regularized problem then corresponds to the projection of a vector on the intersection of the constraints with respect to the Kullback-Leibler distance. Iterative Bregman projections on each marginal constraint are explicit which enables us to approximate the optimal transport plan. We validate the numerical method against analytical test cases
Quality Traits of "Cannabidiol Oils": Cannabinoids Content, Terpene Fingerprint and Oxidation Stability of European Commercially Available Preparations
Cannabidiol (CBD)-based oil preparations are becoming extremely popular, as CBD has been shown to have beneficial effects on human health. CBD-based oil preparations are not unambiguously regulated under the European legislation, as CBD is not considered as a controlled substance. This means that companies can produce and distribute CBD products derived from non-psychoactive hemp varieties, providing an easy access to this extremely advantageous cannabinoid. This leaves consumers with no legal quality guarantees. The objective of this project was to assess the quality of 14 CBD oils commercially available in European countries. An in-depth chemical profiling of cannabinoids, terpenes and oxidation products was conducted by means of GC-MS and HPLC-Q-Exactive-Orbitrap-MS in order to improve knowledge regarding the characteristics of CBD oils. Nine out of the 14 samples studied had concentrations that differed notably from the declared amount, while the remaining five preserved CBD within optimal limits. Our results highlighted a wide variability in cannabinoids profile that justifies the need for strict and standardized regulations. In addition, the terpenes fingerprint may serve as an indicator of the quality of hemp varieties, while the lipid oxidation products profile could contribute in evaluation of the stability of the oil used as milieu for CBD rich extracts