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Series: Other Talks

(algebraic statistics reading seminar)

Series: Other Talks

(algebraic statistics reading seminar)

Series: Other Talks

Series: Other Talks

(algebraic statistics reading seminar)

Series: Other Talks

Host: Turgay Uzer, School of Physics

Annual Joseph Ford Commemorative Lecture: I will describe several models for running insects, from an
energy-conserving biped, through a muscle-actuated hexapod driven by a
neural central pattern generator, to a reduced phase-oscillator model
that captures the dynamics of unperturbed gaits and of impulsive
perturbations. I will argue that both simple models and large simulations
are necessary to understand biological systems. The models show that
piecewise-holonomic constraints due to intermittent foot contacts confer
asymptotic stability on the feedforward system, while leg force sensors
modulate motor outputs to mitigate large perturbations. Phase response
curves and coupling functions help explain reflexive feedback mechanisms.
The talk will draw on joint work with Einat Fuchs, Robert Full, Raffaele
Ghigliazza, Raghu Kukillaya, Josh Proctor, John Schmitt, and Justin
Seipel. Research supported by NSF and the J. Insley Blair Pyne Fund of
Princeton University.

Series: Other Talks

On a smooth manifold, we consider a non-autonomous ordinary differential
equation whose right side switches between finitely many smooth vector
fields at random times. These switching times are exponentially
distributed to guarantee that the resulting random dynamical system has
the Markov property. A Hoermander-type hypoellipticity condition on a
recurrent subset of the manifold is then sufficient for uniqueness and
absolute continuity of the invariant measure of the Markov semigroup.
The talk is based on a paper with my advisor Yuri Bakhtin.

Series: Other Talks

Hosted by the College of Computing

Light refreshments served at 4:30 PM

You are cordially invited to "Health and Wealth," a distinguished lecture by Nobel Laureate
Ken Arrow that will provide a policy guide for matters of health, public and private.
Professor Arrow, Joan Kenney Professor of Economics and Professor of Operations, Emeritus,
at Stanford University, will address longevity and other aspects of health as commodities,
as well as their trade-off with more usual goods as important measures of the well-being of nations.
Register: http://www.formdesk.com/collegeofcomputing/KenArrow

Series: Other Talks

(algebraic statistics reading seminar; note unusual time)

Series: Other Talks

(algebraic statistics reading seminar)

Series: Other Talks

In the lecture I will describe how several questions in geometric combinatorics translate into questions about graphs and hypergraphs. 1. Borsuk's problem. 2. Tverberg theorem and Tverberg's type problems. Tverberg's theorem asserts that (r-1)(d+1)+1 points in d-space can be divided into r parts whose convex hull intersect. I will discuss situations where less points admit such a partition and connections with graph theory. (For more background, look at this MO question Tverberg partitions with less than (r-1)(d+1)+1 points<http://mathoverflow.net/questions/88718/tverberg-partitions-with-less-than-r-1d11-points> ) 3. Helly type theorems and conditions on induced subgraphs and sub-hypergraphs. I will explain the origin to the following conjecture of Meshulam and me: There is an absolute upper bound for the chromatic number of graphs with no induced cycles of length divisible by 3. 4. Embedding of 2-dimensional complexes and high dimensional minors. I will discuss the following conjecture: A 2-dimensional simplicial complex with E edges and F 2-dimensional faces that can be embedded into 4-space satisfies F < 4e. (For more background see my post *F ≤ 4E*<http://gilkalai.wordpress.com/2013/02/01/f-4e/> )