BEGIN:VCALENDAR
VERSION:2.0
PRODID:researchseminars.org
CALSCALE:GREGORIAN
X-WR-CALNAME:researchseminars.org
BEGIN:VEVENT
SUMMARY:Rebecca Waldecker (University of Halle-Wittenberg)
DTSTART:20210324T121000Z
DTEND:20210324T130000Z
DTSTAMP:20260417T002425Z
UID:KuelshammerColl/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/KuelshammerC
 oll/1/">Finite simple groups acting with low mixed fixity</a>\nby Rebecca 
 Waldecker (University of Halle-Wittenberg) as part of Colloquium on the oc
 casion of B. Külshammer's retirement\n\n\nAbstract\nThe classification of
  finite simple groups that act transitively and with fixity at most 4 is a
 lmost complete\, so we begin to focus more on follow-up questions. One of 
 them is to understand if and how our examples can actually occur as automo
 rphism groups of Riemann surfaces. In this talk we will discuss the necess
 ary background and then look at groups that\noccur with what we call "mixe
 d fixity".\n
LOCATION:https://researchseminars.org/talk/KuelshammerColl/1/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Radha Kessar (City University London)
DTSTART:20210324T131000Z
DTEND:20210324T140000Z
DTSTAMP:20260417T002425Z
UID:KuelshammerColl/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/KuelshammerC
 oll/2/">Life on the edge of block theory</a>\nby Radha Kessar (City Univer
 sity London) as part of Colloquium on the occasion of B. Külshammer's ret
 irement\n\n\nAbstract\nThe theory of fusion systems\, the theory of p-comp
 act groups and the theory of spetses all offer different perspectives on g
 roups. I will present some results on the interaction between these theori
 es and block theory. This is joint work with Lynd-Linckelmann-Semeraro and
  with  Malle-Semeraro.\n
LOCATION:https://researchseminars.org/talk/KuelshammerColl/2/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Harvey Blau (Northern Illinois University)
DTSTART:20210324T144000Z
DTEND:20210324T153000Z
DTSTAMP:20260417T002425Z
UID:KuelshammerColl/3
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/KuelshammerC
 oll/3/">Uncharacteristic Proofs of Two Theorems on Group Characters</a>\nb
 y Harvey Blau (Northern Illinois University) as part of Colloquium on the 
 occasion of B. Külshammer's retirement\n\n\nAbstract\nSome structure theo
 rems for table algebras\, in particular for fusion rings\, yield results o
 n characters of finite groups as immediate consequences. One is a well kno
 wn theorem of Isaacs and Passman.  Another was born as a table algebra cor
 ollary.\n
LOCATION:https://researchseminars.org/talk/KuelshammerColl/3/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Robert Boltje (University of California\, Santa Cruz)
DTSTART:20210324T154000Z
DTEND:20210324T163000Z
DTSTAMP:20260417T002425Z
UID:KuelshammerColl/4
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/KuelshammerC
 oll/4/">The Broué invariant of a $p$-permutation equivalence</a>\nby Robe
 rt Boltje (University of California\, Santa Cruz) as part of Colloquium on
  the occasion of B. Külshammer's retirement\n\n\nAbstract\nLet $G$ and $H
 $ be finite groups and let $B$ and $C$ be $p$-block algebras of $G$ and $H
 $\, respectively. In a landmark paper\, Broué defined the notion of a per
 fect isometry $I$ between $B$ and $C$ as a bijection between their irreduc
 ible characters with signs satisfying certain arithmetic conditions. He pr
 oved that the ratio of the codegrees of corresponding irreducible characte
 rs (including the sign) leads to a nonzero element $\\beta(I)$ in the fiel
 d with $p$ elements which is independent of the irreducible characters. We
  call $\\beta(I)$ the Broué invariant of $I$ and show that if $I$ comes f
 rom a $p$-permutation equivalence or a splendid Rickard equivalence betwee
 n $A$ and $B$ then - up to a sign - it is independent of the equivalence a
 nd explicitly determined by local invariants of $B$ and $C$.\n
LOCATION:https://researchseminars.org/talk/KuelshammerColl/4/
END:VEVENT
END:VCALENDAR