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UID:8095@i2m.univ-amu.fr
DTSTART;TZID=Europe/Paris:20150420T000000
DTEND;TZID=Europe/Paris:20150424T000000
DTSTAMP:20241120T210026Z
URL:https://www.i2m.univ-amu.fr/evenements/approximation-and-combinatorics
 -morlet-chair-herwig-hauser/
SUMMARY:Small group (CIRM\, Luminy\, Marseille): Approximation and Combinat
 orics (Morlet Chair - Herwig Hauser)
DESCRIPTION:Small group: \n\n\n\n\n CIRM - Jean-Morlet Chair \n Herwig Haus
 er &amp\; Guillaume Rond\n\nSingularities and Artin Approximation​\n\nSi
 ngularités et approximation de Artin \n\n\n 2015-Semester 1 \n\n\n\n\n\n\
 n\n\n\n\n\n\n\n\n\n\nSMALL GROUP\nApproximation and Combinatorics (1310)\n
 Approximation et combinatoire\nDates: 20-24 April 2015 at CIRM (Marseille\
 , France)      \nPlace : CIRM (Marseille Luminy\, France)\n\n\n  \n\n\n
 \n\n\n\n\n\n\n\n\n\n\n PARTICIPANTS \n\n\n\n\n\n\n\n\n\n\nDESCRIPTION\nGen
 erating series for counting functions abound in combinatorics. Their prope
 rties (formal\, analytic\, algebraic\, rational\, D-finite\, holonomic) pr
 ovide information on the analytic and algebraic relations among the coeffi
 cients. These properties are often very hard to detect\, and suitable tech
 niques for this would be very welcome.\n\nFor instance\, Bostan and Kauers
  have proven that the generating function of Gessel walks is algebraic\, b
 ut the proof is very complicated and relies on a huge computer implementat
 ion. This is precisely a situation where the standard tool to prove algebr
 aicity\, the division theorem\, is not applicable since the divisor series
  is not regular.\n\nThe workshop aims at understanding better the appearan
 ce of analytic or algebraic power series in combinatorics\, to look out fo
 r new tools\, and to compare them with D-finite and holonomic series.\n\nO
 n the other hand\, certain combinatorial identities can be expressed throu
 gh the equality of their generating functions\, as is the case e.g. for th
 e Rogers-Ramanujan identity. Bruschek\, Mourtada and Schepers showed that 
 one side of the RR identity appears as the Hilbert-Poincaré-series of an 
 arc space\, namely nilpotent arcs defined by x(t)²= 0. This suggests to i
 nterpret also the other side of the identity through arc spaces and then t
 o prove the identity by methods of algebraic geometry. This\, however\, is
  still an open problem.\n\n\n \n\nSCIENTIFIC &amp\; ORGANIZING COMMITTEE\
 n\n\n 	Herwig Hauser (Vienna)\n 	Christoph Koutschan (RICAM Austria)\n 	Gu
 illaume Rond (Aix-Marseille)\n\n\n\nSPEAKERS\n\n\n 	Boris Adamczewski (CNR
 S\, Aix-Marseille)\n 	Cyril Banderier (CNRS\, Paris 13)\n 	Mireille Bousqu
 et-Mélou (CNRS\, Bordeaux)\n 	Eric Delaygue (Lyon)\n 	Trung Cuong Doan (H
 anoi)\n 	Herwig Hauser (Vienna)\n 	Christoph Koutschan (RICAM Austria)\n 	
 Christian Krattenthaler (Vienna)\n 	Mickaël Matusinski (Bordeaux)\n 	Kili
 an Raschel (CNRS\, Tours)\n 	Valerie Roitner (Vienna)\n 	Guillaume Rond (A
 ix-Marseille)\n 	Bruno Salvy (ENS Lyon)\n 	Kaloyan Slavov (American Univ. 
 of Bulgaria)\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\nSPONSORS\n\n  \n\n\n\n\n
 \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
CATEGORIES:Manifestation scientifique,Morlet Chair Semester,Morlet Small
 Group
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