Archive 2014

Mathe. Kolloquium: Prof. Kang Zuo (Mainz)

Ort: Hörsaal 1, Arnimallee 3

11.12.2014 | 17:15
06.11.2014 | 17:15
17.07.2014 | 16:15
05.06.2014 | 17:15

Vortrag: Dr. Christian Lehn (Paris 7)

Ort: SR 032, Arnimallee 6

23.05.2014 | 15:00 s.t

Vortrag: Dr. Lars Kindler (FU Berlin)

Ort: SR 032, Arnimallee 6

23.05.2014 | 12:30
23.05.2014 | 10:15

Vortrag: Dr. Joana Cirici (FU Berlin)

Ort: SR 031, Arnimallee 6

23.05.2014 | 08:00 s.t
22.05.2014 | 16:15
15.05.2014 | 17:15

Mathe. Kolloquium: Prof. Boris Hasselblatt (Tufts University, Medford, MA/US)

Ort: Seminarraum des Konrad-Zuse-Zentrums für Informationstechnik (ZIB), Takustr. 7, 14195 Berlin-Dahlem

29.04.2014 | 16:15
06.02.2014 | 17:15

Mathe. Kolloquium: Dr. Vijaya Trivedi (Mumbai / Berlin)

Abstract:  We know that a Frobenius pull back of a semistable bundle need not remain semistable. However, if X is a nonsingular projective curve of genus g and defined over a field of characterstic p > 0, then Shepherd-Barron and X. Sun proved (independently), that for a semistable vector bundle V of rank r, the instability degree of F * V is bounded by  2(g-1)(r-1).  This bound on the instability is useful in keeping a check on some of the  behaviour of a vector bundle afterFrobenius pullbacks. For example one can prove that, for any vector bundle V and for large  p (in terms of degree of X and rank of V), the Harder-Narasimhan filtration of F * V is a refinement of the  Frobenius pull back of the Harder-Narasimhan filtration of V.We give counterexamples to prove that some such conditions on p is necessary.   We extend such results to vector bundles over  higher dimesional verieties.To prove these, we answer a question/conjecture of X. Sun (though  for p bigger than rank of E + dimension of X), which is an anaolgue  of  the above mentioned result of Shepherd-Barron and X. Sun in higher dimension.

Ort: Hörsaal 1, Arnimallee 3

16.01.2014 | 17:15