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UID:c628807c1f262a1cf5185743f43e0c9e
CATEGORIES:Special Seminar
CREATED:20250323T172655
SUMMARY:On permutation statistics, root enumeration and Gelfand models
LOCATION:Hill 705
DESCRIPTION:The k-th root enumerator of a finite group G is an integer valued function 
 on G, which counts the number of k-th roots of each element.\nA long-standi
 ng open problem is to classify the finite groups, for which the k-th root e
 numerator is a proper (non-virtual) character for all k.\nAnother well know
 n problem is to construct Gelfand models;  these are multiplicity-free sums
  of all the irreducible characters of a finite group.\n \nIt will be shown 
 that for all classical Weyl groups, all k-th root enumerators are proper, e
 xtending the results of Scharf and Thibon.\nThe proof is constructive and p
 resents the root enumerator as a multiplicity-free sum of higher Lie charac
 ters. \nRelated constructions of Gelfand models for classical and affine We
 yl groups will be presented.\nApplications to permutation statistics will b
 e described.\n \nBased on joint works with Ron Adin and Pal Hegedus.\n
X-ALT-DESC;FMTTYPE=text/html:<p style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-s
 ize: small; font-weight: 400; letter-spacing: normal; orphans: 2; text-alig
 n: start; text-indent: 0px; text-transform: none; white-space: normal; wido
 ws: 2; word-spacing: 0px; background-color: #ffffff;">The k-th root enumera
 tor of a finite group G is an integer valued function on G, which counts th
 e number of k-th roots of each element.</p><p style="color: #222222; font-f
 amily: Arial, Helvetica, sans-serif; font-size: small; font-weight: 400; le
 tter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text
 -transform: none; white-space: normal; widows: 2; word-spacing: 0px; backgr
 ound-color: #ffffff;">A long-standing open problem is to classify the finit
 e groups, for which&nbsp;the k-th root enumerator is a proper (non-virtual)
  character for all k.</p><p style="color: #222222; font-family: Arial, Helv
 etica, sans-serif; font-size: small; font-weight: 400; letter-spacing: norm
 al; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; 
 white-space: normal; widows: 2; word-spacing: 0px; background-color: #fffff
 f;">Another well known problem is to construct Gelfand models;&nbsp; these 
 are multiplicity-free sums of all the irreducible characters of a finite gr
 oup.</p><p style="color: #222222; font-family: Arial, Helvetica, sans-serif
 ; font-size: small; font-weight: 400; letter-spacing: normal; orphans: 2; t
 ext-align: start; text-indent: 0px; text-transform: none; white-space: norm
 al; widows: 2; word-spacing: 0px; background-color: #ffffff;">&nbsp;</p><p 
 style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size
 : small; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: 
 start; text-indent: 0px; text-transform: none; white-space: normal; widows:
  2; word-spacing: 0px; background-color: #ffffff;">It will be shown that fo
 r all classical Weyl groups, all k-th root enumerators are proper,&nbsp;ext
 ending the results of Scharf and Thibon.</p><p style="color: #222222; font-
 family: Arial, Helvetica, sans-serif; font-size: small; font-weight: 400; l
 etter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; tex
 t-transform: none; white-space: normal; widows: 2; word-spacing: 0px; backg
 round-color: #ffffff;">The proof is constructive and presents the root enum
 erator as a multiplicity-free sum of higher Lie characters.&nbsp;</p><p sty
 le="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size: s
 mall; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: sta
 rt; text-indent: 0px; text-transform: none; white-space: normal; widows: 2;
  word-spacing: 0px; background-color: #ffffff;">Related constructions of Ge
 lfand models for classical and affine Weyl groups will be presented.</p><p 
 style="color: #222222; font-family: Arial, Helvetica, sans-serif; font-size
 : small; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: 
 start; text-indent: 0px; text-transform: none; white-space: normal; widows:
  2; word-spacing: 0px; background-color: #ffffff;">Applications to permutat
 ion statistics will be described.</p><p style="color: #222222; font-family:
  Arial, Helvetica, sans-serif; font-size: small; font-weight: 400; letter-s
 pacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-trans
 form: none; white-space: normal; widows: 2; word-spacing: 0px; background-c
 olor: #ffffff;">&nbsp;</p><p style="color: #222222; font-family: Arial, Hel
 vetica, sans-serif; font-size: small; font-weight: 400; letter-spacing: nor
 mal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none;
  white-space: normal; widows: 2; word-spacing: 0px; background-color: #ffff
 ff;">Based on joint works with Ron Adin and Pal Hegedus.</p>
CONTACT:Yuval Roichman, Bar Ilan University
DTSTAMP:20260827T115846
DTSTART;TZID=America/New_York:20250324T170000
DTEND;TZID=America/New_York:20250324T180000
SEQUENCE:0
TRANSP:OPAQUE
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