BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//wp-events-plugin.com//6.4.7.2//EN
TZID:Europe/Paris
X-WR-TIMEZONE:Europe/Paris
BEGIN:VEVENT
UID:1-531@lptms.universite-paris-saclay.fr
DTSTART:20171006T140000Z
DTEND:20171006T170000Z
DTSTAMP:20170920T080320Z
URL:https://www.lptms.universite-paris-saclay.fr/seminars/soutenance-de-th
 ese-maksim-sevelev/
SUMMARY:Soutenance de thèse: Maxime Sevelev - IPN-batiment 100\, Auditoriu
 rm - 6 Oct 17 14:00
DESCRIPTION:Phase diagram\, jamming and glass transitions in the non-convex
  perceptron\nMaxime Sevelev\nThis thesis treats the «spherical perceptron
  model»\, a simple exactly solvable model for glassy behavior and jamming
  suitably generalized to negative values of scalar product parameter κ. T
 he classical machine-learning problem of random pattern classification by 
 the perceptron is a convex constraint satisfaction problem (CSP). Even whe
 n the «stability parameter» κ of the model becomes negative\, the probl
 em still makes sense and can be interpreted as the problem of particles on
  an N-dimensional sphere trying to avoid randomly placed obstacles. In thi
 s case\, the corresponding CSP is non-convex. This thesis studies the prob
 lem in detail in the non-convex domain. Systematic study is made possible 
 by assigning to a constraint satisfaction problem its corresponding optimi
 zation version endowed with a Hamiltonian function (cost function) quantif
 ying the violations of the constraints\, as a function of the system's con
 figuration. The connection between random CSP and glassy phenomenology in 
 physics is well known and has been explored in detail for models with disc
 rete variables. The presence of continuous variables in the (spherical) pe
 rceptron model enables us to unveil\, in random CSP\, the characteristic S
 AT/UNSAT transition where the system transits from the satisfiable regime 
 (where the ground state has zero energy) to the unsatisfiable one (where t
 he ground state energy is positive). This phase transition can also be int
 erpreted as a jamming transition similar to the one that exhibit models wi
 th frictionless spheres. The simplicity of the considered model allows the
  exact determination of the zero temperature phase diagram as a function o
 f the control parameters: the density of obstacles and their size. In the 
 present thesis\, the jamming transition thus identified is completely char
 acterized and several glass phases of stable and marginal character are st
 udied in detail.\nKeywords: spin glass\, phase transition\, disordered sys
 tem\, jamming\n\nDirecteur de thèse: S. Franz\n\nJury: R. Mulet\, F. Ricc
 i.tersenghi\, V. Lecomte\, M. Tarzia\, V. Terras\, C. Texier.
CATEGORIES:seminars
LOCATION:IPN-batiment 100\, Auditoriurm\, 15 Rue Georges Clemenceau\, orsay
 \, France
GEO:48.698196;2.181773
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=15 Rue Georges Clemenceau\,
  orsay\, France;X-APPLE-RADIUS=100;X-TITLE=IPN-batiment 100\, Auditoriurm:
 geo:48.698196,2.181773
END:VEVENT
END:VCALENDAR