Mathematics Seminar at ICTP - next week

[Math]

M A T H E M A T I C S   S E M I N A R S   2007


Tuesday, 29 May at 14:00 hrs.


Professor Takuro Abe
(Hokkaido University, Sapporo, Japan)

"Free and non-free multiplicity on hyperplane arrangements"

Abstract: A multiarrangement, which is a collection of hyperplanes  
with multiplicities, was introduced by Ziegler for the purpose of  
solving several problems of free arrangements, e.g., Terao  
conjecture. There are several interesting studies related to  
multiarrangements, its logarithmic vector fields and freenss by  
Solomon, Terao, and Yoshinaga. Especially, Yoshinaga proved that  
Terao conjecture is closely related to free multiarrangements. In  
this talk, we give two useful theorems to consider the freeness of  
multiarrangements, i.e., the addition-deletion theorem and  
characteristic polynomial. As an application, we classify the free  
and non-free graphic multiplicity on the Coxeter arrangements of type  
$A_\ell$. The main part of this talk is joint work with Hiroaki Terao  
and Max Wakefield.

VENUE:  SEMINAR ROOM (ICTP Main Building, first floor)