Hyperplane Arrangement Seminar

Contents

Program

[7th]
Time＆Date:
10:30 - 12:00, October 30, 2007
Venue:
8-302, Faculty of Science Building #8, Hokkaido University
Speaker:
Masahiko Yoshinaga (Kobe University)
Title:
On the extendability for some free multiarrangements
Abstract:
A free multiarrangement of rank k is defined to be extendable if it is obtained from a simple rank (k+1)free arrangement by the natural restriction (in the sense of Ziegler) to a hyperplane. Not all free multiarrangements are extendable. We will concentrate on a special class of extendable free multiarrangements. As an application, we find a large class of totally non-free arrangements.
[8th]
Time＆Date:
13:00 - 14:30, October 30, 2007
Venue:
8-302, Faculty of Science Building #8, , Hokkaido University
Speaker:
Yukihito Kawahara (Keio Shiki Boys' Senior High School)
Title:
Combinatorics of arrangements with non-vanishing twisted cohomology
Abstract:
In the general twist case, twisted cohomology on the complement of hyperplanes vanishes except in the highest dimension. For the special arrangement of hyperplanes, there is a twist with non-vanishing twisted cohomology. In this talk, we construct such arrangements, using some combinatorics.