Seminars in October 2010

  • Masahiko Yoshinaga (吉永正彦), On the Free Arrangements and Truncated Affine Weyl Arrangements
    On the free arrangements and truncated affine Weyl arrangements
    Masahiko Yoshinaga (吉永正彦)
    Department of Mathematics, Kyoto University, Kyoto, Japan.
    2010/10/26 Tue 4PM-5PM (Room 3433)

    Freeness of a hyperplane arrangement is defined algebraically using module of derivations. I will discuss freeness of certain truncated affine Weyl arrangements, called the extended Catalan/Shi arrangements. I will also talk some enumerative corollaries.

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  • Sen-Peng Eu (游森棚), On Cyclic Sieving Phenomena
    On Cyclic Sieving Phenomena
    Sen-Peng Eu (游森棚)
    Department of Applied Mathematics, National University of Kaohsiung, Taiwan.
    2010/10/25 Mon 4PM-5PM (Room 3433)

    The cyclic sieving phenomenon is introduced by Reiner, Stanton and White in 2004. Since then this new topic attracts more and more attentions of researchers in recent years. In this talk we will introduce the cyclic sieving phenomenon and introduce some interesting old and new results. Finally we present a new development on constructing new cyclic sieving phenomena from new ones via elementary representation theory.

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  • Shuichi Miyazaki (宮崎 修一), Approximation Algorithms for Finding Maximum Stable Matchings
    Approximation algorithms for finding maximum stable matchings
    Shuichi Miyazaki (宮崎 修一)
    Academic Center for Computing and Media Studies, Kyoto University, Kyoto, Japan
    2010/10/15 Fri 4PM-5PM

    The stable marriage problem is a classical matching problem. An input consists of the set of men, the set of women, and each person’s preference list that orders the members of the opposite sex according to the preference. The problem asks to find a stable matching, that is, a matching that contains no (man, woman) pair, each of which prefers the other to his/her current partner in the matching.

    One of the practical extensions is to allow participants to use ties in preference lists and to exclude unacceptable persons from lists. In this variant, finding a stable matching of maximum size is NP-hard. In this talk, we give some of the approximability results on this problem.

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