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UID:0-1050@lptms.universite-paris-saclay.fr
DTSTART;TZID=Europe/Paris:20250930T110000
DTEND;TZID=Europe/Paris:20250930T120000
DTSTAMP:20250925T135858Z
URL:http://www.lptms.universite-paris-saclay.fr/seminars/seminaire-du-lptm
 s-alexander-k-hartmann-institute-for-physics-university-of-oldenburg-germa
 ny/
SUMMARY:Séminaire du LPTMS : Alexander K. Hartmann (Institute for Physics\
 , University of Oldenburg\, Germany) - Salle des séminaires du FAST et du
  LPTMS\, bâtiment Pascal n°530 - 30 Sep 25 11:00
DESCRIPTION:Complex behavior for numerically simple problems\n\nAlexander K
 . Hartmann (Institute for Physics\, University of Oldenburg\, Germany)\n&n
 bsp\;\n\nThe description of complex system by the concept of Replica Symme
 try Breaking (RSB) was shaped by Giorgio Parisi in the 1980s to solve the 
 mean-field spin glass\, as honored by the Nobel price in 2021. RSB has bee
 n used to analyze systems such as spin glasses\, neural networks\, optimiz
 ation problems\, or machine learning. Unfortunately\, numerically these we
 ll known RSB-exhibiting problems are difficult since only exponential-time
  exact algorithm are available.\n\nHere two models are considered\, direct
 ed polymers in random media and increasing subsequences\, called Ulam's pr
 oblem for the ground states. These models are interesting in many ways. Fo
 r example\, the distributions of free energies or sequence lengths\, respe
 ctively\, exhibit complex large-deviation behavior\, which can be numerica
 lly addressed by rare-event sampling algorithms.\n\nFor both models it is 
 possible to sample exactly in perfect thermal equilibrium with polynomial-
 time algorithms. This means\, large\nsystem sizes are accessible\, in cont
 rast to\, e.g.\, the case of spin glasses. The results from perfect sampli
 ng of some problem disorder ensembles indicate the presence of RSB with co
 mplex structured landscapes. Thus\, the study of complex RSB behavior is a
 ccessible numerically for some models.
CATEGORIES:seminars
LOCATION:Salle des séminaires du FAST et du LPTMS\, bâtiment Pascal n°53
 0\, rue André Riviere\, Orsay\, 91405\, France
X-APPLE-STRUCTURED-LOCATION;VALUE=URI;X-ADDRESS=rue André Riviere\, Orsay\
 , 91405\, France;X-APPLE-RADIUS=100;X-TITLE=Salle des séminaires du FAST 
 et du LPTMS\, bâtiment Pascal n°530:geo:0,0
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DTSTART:20250330T030000
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