+ 理学部数学科 + OCAMI + 2015年度

Friday Seminar on Knot Theory(2016年度)

組織委員 安部 哲哉・岡崎 真也


今後の講演

日時4月8日(金)16:00~17:00
講演者河内明夫 (OCAMI)
タイトル On a cross-section of an immersed sphere-link in 4-space
場所 理学部 F棟 415号室 (中講究室)

The torsion Alexander polynomial, the reduced torsion Alexander polynomial and the local signature invariant of a cross-section of an immersed sphere-link are investigated from the viewpoint of how to influence to the immersed sphere-link. It is shown that the torsion Alexander polynomial of a symmetric middle cross-section of a ribbon sphere-link is an invariant of the ribbon sphere-link. A generalization to a symmetric middle cross-section of an immersed ribbon sphere-link is given.

日時5月13日(金)16:00~17:00
講演者Sang Youl Lee (Pusan National University)
タイトル TBA
場所 理学部 F棟 415号室 (中講究室)

TBA

日時5月27日(金)16:00~17:00
講演者和田 康載 (早稲田大学)
タイトル Milnor invariants of covering links
場所 理学部 F棟 415号室 (中講究室)

We consider Milnor invariants for certain covering links as a generalization of covering linkage invariants formulated by R. Hartley and K. Murasugi. A set of Milnor invariants for covering links is a cobordism invariant of a link, and that this invariant can distinguish some links for which the ordinary Milnor invariants coincide. Moreover, for a Brunnian link $L$, the first non-vanishing Milnor invariants of $L$ is modulo-$2$ congruent to a sum of Milnor invariants of covering links. As a consequence, a sum of linking numbers of "iterated" covering links gives the first non-vanishing Milnor invariant of $L$ modulo $2$. This talk is a joint work with Natsuka Kobayashi and Akira Yasuhara.

日時6月17日(金)16:00~17:00
講演者村上広樹 (東京工業大学)
タイトル Alternating links and root polytopes
場所 理学部 F棟 415号室 (中講究室)

In this talk, a relationship between the determinant of an alternating link and a certain polytope obtained from the link diagram is presented. Concretely, we show that the volume of the obtained polytope is proportional to the determinant if the given link is alternating.


最終更新日: 2016年4月8日
管理者: 安部哲哉
tabe(at)sci.osaka-cu.ac.jp