Week of November 21, 2021

Mon Nov 22, 2021
12:00pm - Zoom - Probability and Analysis Webinar
Marcin Bownik - (University of Oregon)
TBA

https://sites.google.com/view/paw-seminar

2:00pm to 3:00pm - 440R - Mathematical Physics
Michael Campbell - (Eureka)
An Elementary Humanomics Approach to Boundedly Rational Quadratic Models

 

 

We take a refreshing new look at boundedly rational quadratic models in economics using some elementary modeling of the principles put forward in the book Humanomics by Vernon L. Smith and Bart J. Wilson. A simple model is introduced built on the fundamental Humanomics principles of gratitude/resentment felt and the corresponding action responses of reward /punishment in the form of higher/lower payoff transfers. There are two timescales: one for strictly self-interested action, as in economic equilibrium, and another governed by feelings of gratitude/resentment. One of three timescale scenarios is investigated: one where gratitude /resentment changes much more slowly than economic equilibrium (“quenched model”). Another model, in which economic equilibrium occurs over a much slower time than gratitude /resentment evolution (“annealed” model) is set up, but not investigated. The quenched model with homogeneous interactions turns out to be a non-frustrated spin-glass model.  For this particular model, the Nash equilibrium has no predictive power of Humanomics properties since the rewards are the same for self-interested behavior, resentful behavior, and gratitude behavior. Accordingly, we see that the boundedly rational Gibbs equilibrium does indeed lead to richer properties.

4:00pm to 5:00pm - Zoom - https://uci.zoom.us/j/97796361534 - Applied and Computational Mathematics
Bangti Jin - (University College London)
Conductivity imaging from current density magnitude using neural networks

Conductivity imaging represents one of the most important tasks in medical imaging. In this talk we discuss a neural network-based technique for imaging the conductivity from the magnitude of the internal current density. It is achieved by formulating the problem as the relaxed weighted least-gradient problem, and then approximating the minimizer by standard feedforward neural networks. We derive bounds on two components of the generalization error, i.e., approximation error and statistical error, explicitly in terms of properties of the neural networks (i.e., depth, total number of parameters, and the bound of the network parameters). We illustrate the performance and distinct features of the proposed approach on several numerical experiments.

Tue Nov 23, 2021
1:00pm to 2:00pm - Zoom - Dynamical Systems
Grisha Monakov - (UC Irvine)
Shadowing in dynamical systems

We say that a dynamical system satisfies shadowing property if for any pseudotrajectory there exists an exact trajectory that is pointwise close to it. This property was introduced by Anosov in 1970th and plays an important role in the theory of dynamical systems. Shadowing property is known to have strong connections with hyperbolicity and structural stability. In this talk I will give an overview of classical results in shadowing theory and will present a new proof of Anosov shadowing lemma.

4:00pm - NS2 1201 - Differential Geometry
Kai-Wei Zhao - (UC Irvine)
On blowup of regularized solutions to Jang equation and constant expansion surfaces

Schoen-Yau proved the spacetime positive energy theorem by reducing
it to the time-symmetric (Riemannian) case using the Jang equation. To
acquire solutions to the Jang equation, they introduced a family of
regularized equations and took the limit of regularized solutions, whereas a
sequence of regularized solutions could blow up in some bounded regions
enclosed by apparent horizons. They analyzed the blowup behavior near but
outside of apparent horizons, but what happens inside remains unknown. In
this talk, we will discuss the blowup behavior inside apparent horizons
through two common geometric treatments: dilation and translation. We will
also talk about the relation between the limits of blowup regularized
solutions and constant expansion surfaces.