# seminar

Studio Phones Seminar

We extended this seminar at Kobe Univerity

Studio Phones Seminar at Kobe University(academic, new)

Upcoming talks

Past seminars

2011/08/23 AM1030-AM1130 / StudioPhones Room301B

"On ring theoretic invariants of quasi-isometry"/ Hokuto Morishima (Osaka University)

* abstract *

* We consider a certain ring for a finitely generated group, and*

* introduce the results about correspondence of the ring and the*

* quasi-isometric geometry of the finitely generated group.*

2011/08/23 PM0100-PM0200 / StudioPhones Room301B

"On pre-computable category" / Yusuke Kiriu (Studio Phones)

joint with A.Ushijima (Kanazawa University)

* abstract *

* This talk is a brief survey of pre-computable category, *

* especially, for topological objects, invariant functions, *

* and algebraic structures.*

* On the background of our research, we are studying *

* computer sciences, logics and linguistics. I also talk about *

* some details of pre-computable category within the context of *

* 2 and 3 dimensional computer graphics and general graphics.*

2011/08/23 PM0210-PM0600 / StudioPhones Room301B

"Introduction to Schubert calculus"/ Shizuo Kaji (Yamaguchi University)

* abstract *

* "How many lines are there in the three space which meet all*

* the four given lines ?"*

* In 19th century, H.Schubert considered this problem in an insightful but*

* not rigorous way.*

* He invented a symbolic "calculation'' for the conditions on lines as follows:*

* [intersecting a given line]^{\cap 4} = [lying on a given line] \cup*

* [lying on a given line], and obtained the answer two.*

* In fact, the "algebra'' of the conditions on lines is isomorphic to the*

* ring of the symmetric polynomials called Schur polynomials.*

* D.Hilbert asked for a rigorous foundation for the above calculus as the*

* 15th problem in his 1900 lecture and now Schubert’s quiz can be rephrased in terms of *

* cohomology, or equivalently, intersection theory of a Grassmaniann manifold.*

* In this talk, I will briefly review the basics of Schubert calculus with a*

* focus on the correspondence of several algebras occurring in this subject*

* including the above one.*

2011/03/08 PM0300-PM0600 / StudioPhones Room301B

"Vertex operator algebras and characters of their modules"/ Yusuke Arike (Osaka University)

* abstract *

* I will explain about Zhu's modular invariance property of characters of modules*

* for rational vertex operator algebras.*

2010/07/29 PM0100-PM0500 / StudioPhones Room301B

On the tetrahedral number of hyperbolic manifolds of bounded volume / Yo'av Rieck (University of Arkansas)

after Jorgensen and Thurston, joint with Tsuyoshi Kobayashi

* abstract *

* In the 70's, Jorgensen and Thruston proved that for any V>0 there*

* exists a finite collection of manifolds X_1,...,X_n so that any*

* complete hyperbolic 3-manifold of volume at most V is obtained by*

* filling some X_i. A well-know "folk theorem" of Thruston says that*

* there exists a constant K so that X_i can be triangulated using at*

* most KV tetrahedra.*

* *

* We will first motivate this theorem by describing two applications.*

* The purpose of this talk is providing a proof of Thurston's theorem.*

* The proof follows an outline that appeared in the litrature, but as*

* remarked by Benedetti and Petronio, it requirs control over the*

* intersection between the Voronoi cells and the thin and thick parts of*

* the manifolds (the terms will be explained in the talk). We will show*

* how we control these intersections.*

* *

* Most of the work is elementary and done in hyperbolic 3-space. I will*

* make an effort to make it accessible to students familiar with the*

* upper half space model.*

2010/06/4 - 6/27

"Workshop(s): Lefschetz fibration and category theory"

Workshop(s): Lefschetz fibration and category theory

2010/03/15 PM0100-PM0500 / StudioPhones Room301B

"On a variation of the Gordian complex" In Dae Jong (Osaka City University)

* abstract *

* This is a joint work with Kazuhiro Ichihara.*

* We will introduce simplicial complexes by using various invariants and*

* *

* local moves on knots, which give generalizations of the Gordian complex*

* *

* defined by Hirasawa and Uchida.*

* *

* In this talk, we will study simplicial complexes defined by using the*

* *

* Alexander-Conway polynomial and the crossing change or the Delta-move.*

* We will show that these simplicial complexes are Gromov hyperbolic.*

2010/02/22, 2010/02/23

Workshop : Arithmetic Kleinian group

https://sites.google.com/site/yusukekiriu/home/osaka_arith

* *2010/02/17 PM0100-PM0300 / StudioPhones Room301B

"On roots of Dehn twists "Naoyuki Monden (Osaka University)

* abstract *

* Margalit and Schleimer constructed nontrivial roots of the*

* Dehn twist about a nonseparating curve.We prove that the *

* conjugacy classes of roots of the Dehn twist about a *

* nonseparating curve correspond to the conjugacy classes*

* of periodic maps with certain conditions.Furthermore, *

* we give data set which determine the conjugacy class of a root.*

* As a consequence, we can find the minimum degree and the *

* maximum degree, and show that the degree must be odd.*

* Also, we give Dehn twist expression of the root of degree 3*

2010/02/17 PM0300-PM0630 / StudioPhones Room301B

"Handle decompositions of knot complements" Tsubasa Ichikawa (Osaka University)

* abstract *

* Every smooth compact n-manifold is decomposed into some *

* copies of n-disks (= handles) according to certain rules. *

* I would like to introduce handle decompositions of manifolds *

* (especially knot complements) and demonstrate how to draw them.*

2010/02/13 AM1000-AM1130 / StudioPhones Room301B

"Quandles and related topics" Yuichi Kabaya (Osaka City University Advanced Mathematical Institute (OCAMI))

* abstract *

* Quandle is an algebraic structure which was introduced by *

* David Joyce in 1982, motivated by knot theory and conjugation *

* of a group.In this talk I will introduce several aspects of *

* quandles and related topics; quandle homology and relation *

* with group homology, rack space, (twisted) Alexander polynomial, etc.*

2010/02/13 PM0100-PM0530 / StudioPhones Room301B

"Iwasawa theory and characteristic invariants" Kazuma Shimomoto

Joint with T.Ochiai (Osaka University)

* abstract*

* In recent years, several people have suggested the various kinds of *

* Iwasawa Main Conjecture formulated in the language used in their *

* own field of study.*

* In this talk, I begin with a brief review on classical Iwasawa theory, *

* including the classical Main Conjecture. Then I move on to the*

* p-adic modular forms, L-functions, and the Main Conjecture.*

* The main theme of this talk is to discuss Bertini-type theorem and *

* characteristic invariants which also serve as strategic tools *

* to study similar invariants in toplogy and algebra. *

*2010/02/10 AM0930-AM1130 / StudioPhones Room301B*

"Application of Length of Quandle 3-Cocycle to Surface-Knot Theory" Shin Satoh (Kobe University)

* abstract*

* The homology and cohomology theory of a quandle is useful to *

* study knotted surfaces in 4-space. We define the length of a *

* 3-cocycle of a quandle equipped with a quandle-set, and calculate *

* the lengths of some 3-cocycles. We give lower bounds of the triple *

* point number of a surface-knot by the length of a quandle 3-cocycle.*

*2010/02/10 PM0100-PM0530 / StudioPhones Room301B*

"On quandle homology groups of Alexander quandles of prime order" Takefumi Nosaka (RIMS, Kyoto University)

* abstract*

* Our result is to determine all quandle homology groups of Alexander *

* quandle of prime order. The proof is obtained from the calculations of*

* quandle 'co'homology group with the generators (cocycles) by means *

* of calculus over positive characteristic, which is inspired by *

*T.Mochizuki's computations of third degree cocycles. *

* This talk outlines the proof, and our goal is to illustate why 'the *

* higher degree cocycles are constructed from lower degree ones, *

* and linear independently generate the quandle cohomology group'.*

2009/12/30 AM1000-PM0100 / StudioPhones Room301B

"Similarity between Alexander-Fox Theory and Iwasawa Theory" Teruhisa Kadokami (Dalian University of technology)

* abstract*

* I explain about similarity between Alexander-Fox Theory from*

* Knot Theory, and Iwasawa Theory from Number Theory.*

2009/12/30 PM0230-PM0430 / StudioPhones Room301B

"On F-coherent rings" Kazuma Shimomoto

* abstract*

* I will talk about a new class of Noetherian rings defined by the*

* Frobenius map and discuss its basic properties.*

* The talk will also focus on some open questions.*

2009/12/30 PM0430-PM0530 / StudioPhones Room301B

"Bertini type theorem and Iwasawa Main Conjecture" Kazuma Shimomoto

Joint with T.Ochiai (Osaka University)

* abstract*

* Iwasawa Main Conjecture (IMC) in two variables was*

* proposed by several people and proved by K.Rubin in the classical case. *

* More recently, T.Ochiai formulated IMC over some type of deformation *

* spaces and he proved it in the case when the deformation space is the *

* Iwasawa algebra.His idea is to take sufficiently many hypersurfaces*

* and analyze the problem on them.I will talk about the so-called Bertini *

* type theorem to generalize IMC to more general deformation spaces. *

2009/12/05 AM1000-PM0600 / 2nd Floor, Lecture Room, Kanazawa University Satellite Plaza

"Godel's incompleteness theorem and its application" Shunsuke Yatabe (National Institute of Advanced Industrial Science and Technology)

* abstract*

* In this talk, we introduce an overview of a proof of Godel's*

* incompleteness theorem. First we see the details of arithmetization of*

* natural number theory, then we see how Godel sentence is constructed.*

* Then we see the arithmetical hierarchy and its "circular structure" in*

* Global sense.*

* If we have enough time, we also try to see some facts about non-standard*

* model of Arithmetic.*

2009/10/08 PM0100-PM0600 / StudioPhones Room301B

"An Application of Category Theory to Systems Biology" Taichi Haruna (Kobe University/JST)

* abstract*

* We propose a new data analytical tool for directed networks by*

* using category theory.*

* We develop a category theoretical treatment of directed networks in*

* order to obtain functional networks for real networks. *

* By applying our method to concrete data on real information*

* processing biological networks, we find a distinguishing global*

* structure of functional networks.*

* We discuss a possibility of a new hypothesis on network motifs based on*

* our theory and data analysis.*

* We also present a glimpse of calculations when our method is thought of*

* an abstract graph transformation.*

* *

2009/10/30 AM1000-PM0600 / Hiroshima University

小研究集会;Symbolic description and low-dimensional topology

基盤研究B

「3次元多様体のヘガード構造と幾何構造 」

研究課題番号：18340018

代表者：作間誠

により支援を受けています

2009/10/16~18 AM0900-PM0600 / Shinshu University

Workshop : Category Theory , Computer Science and Topology

学長裁量経費 (教育・研究経費)

「数理科学分野の連携と融合，創成：信州数理科学特別重点研究」

研究代表者: 井上和行

により部分的に支援を受けています

2009/10/14 AM1000-AM1200 / StudioPhones Room301B

"Cohen-Macaulay modules over Gorenstein rings" Tokuji Araya (Nara University of Education)

* abstract*

* Gorenstein rings have nice homological properties to investigate the*

* category of finitely generated modules.*

* In this talk, I will give some basic properties of Cohen-Macaulay modules*

* over Gorenstein rings.*

2009/10/14 PM0100-PM0500 / StudioPhones Room301B

"Cohen-Macaulay modules over Gorenstein rings" Tokuji Araya (Nara University of Education)

* abstract*

* Gorenstein rings have nice homological properties to investigate the*

* category of finitely generated modules.*

* In this talk, I will give some basic properties of Cohen-Macaulay modules*

* over Gorenstein rings.*

2009/ 9/27 AM1000-PM0100 / StudioPhones Room301B

"Basics of plane curves" Hisanori Ohashi (RIMS, Kyoto University)

* abstract*

* I will give an introduction to algebraic geometry. We will see several aspects of*

* algebraic curves, being as conscious to the general theory as possible.*

* If time permits, I will explain the Mathieu group, the first generation*

* of the Happy Family of finite simple sporadic groups.*

*2009/ 9/27 PM0200-PM0400 / StudioPhones Room301B*

"Geometry of second order PDE" Kazuhiro Shibuya (Hiroshima University)

* abstract*

* This is an introduction to exterior differential systems.*

* I will talk the classical theory given by E.Cartan.*

2009/ 9/27 PM0400-PM0600 / StudioPhones Room301B

"Symbolic Manipulation for pure functions" Yusuke Kiriu (Studio Phones)

(Joint with T.Sakasai)

-Mathematica pure functions as being like Lambda expressions or anonymous functions-

* abstract*

* Beginning with a short introduction to symbolic and numeric computation,*

* we discuss interaction between computer science and low-dimensional topology, *

* especially, algorithms and programming paradigms.*

* In this talk, we give an extension language designed specifically to *

* symbolic manipulaton of pure functions by using low-level structures of Mathematica . *

*2009/ 9/25 PM0630-PM1000 / StudioPhones Room301B*

"Kirby's theorem" Tadayuki Watanabe (Hokkaido University)

* abstract*

* Using Cerf theory Kirby proved that two framed links represent*

* diffeomorphic closed 3-manifolds if and only if they are related to*

* each other by a sequence of "Kirby moves" on framed links. A rough*

* sketch of Kirby's proof is explained along his original paper.*

*2009/ 8/22 AM1000-PM0300 / StudioPhones Room301B*

"Towards on analogy of Dehn surgery in number theory" Yasushi Mizusawa (Nagoya Institute of Technology)

* abstract*

* Based on the analogy between Galois groups and Knot groups,*

* we discuss on analogy of the theory of Dehn suregery for knots.*

*2009/ 8/19 PM0100-PM0300 / StudioPhones Room301B*

"Everywhere integral sections of elliptic surfaces" Hisanori Ohashi (RIMS, Kyoto University)

* abstract*

* integral points of elliptic curves have long*

* history in number theory and algebraic geometry. In this talk *

* I will introduce the analogue of integral points in the elliptic*

* surface case, originally defined by T. Shioda.*

* To do so, I will explain elliptic surfaces, their Mordell-Weil*

* lattices, related sphere packings, lattice theory and group theory.*

* The purpose is to overview the subject.*

*2009/ 8/17 AM1000-AM1130 / StudioPhones Room301B*

"Lefschetz fibrations and Teichmuller spaces" Hiroshige Shiga (Tokyo Institute of Technology)

* abstract*

* We discuss interaction between Teichmuller spaces and hoomorphic Lefschetz fibrations.*

*2009/ 8/17 PM0030-PM0530 / StudioPhones Room301B*

"Invariants and constructions of Lefschetz fibrations" Hisaaki Endo (Osaka University)

* abstract*

* Beginning with a short introduction to 4-manifolds,*

* we discuss various properties of Lefschetz fibrations,*

* especially, signature of Lefschetz fibrations and substitution*

* technique for positive relations.*

*2009/ 8/16 AM1000-AM1200 / StudioPhones Room301B*

"Lens spaces and some invariants" Motoo Tange (RIMS, Kyoto University)

* abstract*

* The speaker shall define 3-dimensional lens spaces in some ways*

* and shall compute various topological invariants.*

* We will consider whether we can investigate the Dehn surgery problem*

* from the values.*

*2009/ 8/16 PM0100-PM0530 / StudioPhones Room301B*

"Lens spaces and some invariants" Motoo Tange (RIMS, Kyoto University)

* abstract*

* The speaker shall define 3-dimensional lens spaces in some ways*

* and shall compute various topological invariants.*

* We will consider whether we can investigate the Dehn surgery problem*

* from the values.*

*2009/ 7/25 AM1000-AM1200 / StudioPhones Room301B*

"Standard models of Train tracks" Hideki Miyachi (Osaka University)

* abstract*

* In this talk, we will survey properties of*

* the standard models of train tracks.*

*2009/ 7/18 PM0100-PM0530 / StudioPhones Room301B*

"Dualizing complex of the Stanley ring associated with a simplicial poset" Kohji Yanagawa (Kansai University)

* abstract*

* In 1991, R. Stanley assigned a commutative ring $A_P$*

* to a finite simplicial poset $P$ for a combinatorial purpose.*

* Recently, M. Masuda et al. studied $A_P$ as*

* the equivariant cohomology ring of a torus manifold.*

* In this talk, we give a concise description*

* of the dualizing complex of $A_P$, and show an application.*

*2009/ 5/30 AM1030-AM1130 / StudioPhones Room301B*

"Schubert calculus and combinatorics of words" Hiroshi Naruse (Okayama University)

* abstract*

* In this talk I will explain how combinatorics of words can be used*

* in Schubert calculus, i.e. reducing the problem to calculate topological*

* invariants for Schubert varieties in terms of subword combinatorics of*

* Coxeter groups. There are recurrence relations for canonical classes*

* and structure constants, and explicit formulas for the solutions are*

* given for some special cases.*

*2009/ 5/30 PM0100-PM0600 / StudioPhones Room301B*

"How to overcome Russell paradox (within fuzzy logic)" Shunsuke Yatabe (National Institute of Advanced Industrial Science and Technology)

* abstract*

* It is well known that Russell paradox shows that the naive set theory*

* implies a contradiction within classical logic. However, in 1970's, it*

* turned out that the theory is consistent within many non-classical*

* logics. In this talk, we introduce the case of fuzzy logic.*

* One of the most interesting aspect of such set theory is that it*

* forgives the very strong form of circular definitions. However this*

* makes difficult to construct its models. In this talk we briefly*

* introduce about them.*

* *detail

*2009/ 4/15 AM1000-PM0600 / The University of Tokyo*

* (petit) seminar*

* This seminar is partially supported by Global COE Program*

* "The research and training center for new development in mathematics"*

* (Graduate School of Mathematical Sciences, The University of Tokyo, Leader: Kawamata, Yujiro) *

*2009/ 2/23 PM0300-PM0800 / StudioPhones Room301B*

"Geometric method on Virtual Knot Theory" Teruhisa Kadokami (Dalian University of technology)

* abstract*

* A virtual link is an extended concept of a link in S^3*

* which can be realized as a diagram on S^2 by introducing*

* virtual crossings. Geometrically, a virtual link can be*

* considered as a link in the product space of an oriented*

* closed surface and the closed interval. So we can study*

* virtual links geometrically. I will introduce some geometric*

* methods of Virtual Knot Theory.*

*2009/ 2/20 PM0600-PM0830 / StudioPhones Room301B*

"Teichmueller spaces and Banach spaces in the Teichmueller theory 1" Hideki Miyachi (Osaka University)

* abstract*

* In this talk, I give a brief introduction of the Teichmueller theory.*

* Especially, we will discuss the complex analytic structure of the*

* Teichmueller space.*

*2009/ 2/21 AM1000-PM0400 (PM0100-PM0200 Lunch ) / StudioPhones Room301B*

"Teichmueller spaces and Banach spaces in the Teichmueller theory 2" Hideki Miyachi (Osaka University)

* abstract*

* In this talk, I give a brief introduction of the Teichmueller theory.*

* Especially, we will discuss the complex analytic structure of the*

* Teichmueller space.*

2009/ 2/21 PM0400-PM0830 / StudioPhones Room301B

"When is a Ford-like polygon non-generic?" Akira Ushijima (Kanazawa University)

* abstract*

* The detail of the proof that Ford-like polygons for a given Fuchsian group are *

* generic for almost all points will be discussed in this talk.*

*2009/ 2/22 AM1000-AM1200 / StudioPhones Room301B*

"Limit sets of Kleinian groups" Kentaro Ito (Nagoya University)

* abstract*

* I will explain some basic properties of limit sets of Kleinian groups.*

2009/ 2/20 AM1100 - 2009/ 2/22 PM0700 / StudioPhones Room301B

* Workshop*

*2009/ 2/19 PM0200-PM0800 / Kyoto / Tea & Talks *

"Toric degenerations of Gerfand-Cetlin systems and their applications" Yuichi Nohara (Tohoku University)

* abstract*

* The Gelfand-Cetlin system is a completely integrable system*

* on a flag manifold of type A, whose moment polytope is known*

* as the Gelfand-Cetlin polytope.*

* We show that the Gelfand-Cetlin system can be deformed into*

* a moment map on a toric variety corresponding to the*

* Gelfand-Cetlin polytope.*

* We also discuss an application to disk counting problem.*

*2009/ 2/ 2 PM0100-PM0600 / StudioPhones Room301B*

"Sutured Floer homology and its application" Motoo Tange (RIMS, Kyoto University)

* abstract*

* Juhasz has defined sutured Floer homologies for sutured manifolds.*

* We will talk about its definition, calculation, and applications.*

*2009/ 1/16 PM0100-PM0400 / StudioPhones Room301B*

"Foliations on 3-dimesional manifolds" Hiroko Murai (Tokyo Denki University)

* abstract*

* For a given knot K in the 3-sphere , D. Gabai has given a method for*

* constructing a taut finite depth foliations on the exterior of such that the*

* minimal genus Seifert surface for K is a leaf of the foliation and the*

* restriction of the foliation to the boundary is a foliation by circles. In*

* this talk, we apply the method to 5_2 knot and see the behavior of leaves of*

* the foliation.*

*2008/12/13 AM1130-PM0100 , PM0230-PM0500 / StudioPhones Room301B*

"Quandle and hyperbolic volume" Ayumu Inoue (Tokyo Institute of Technology)

* abstract*

* In this talk, we will show that the hyperbolic volume of a hyperbolic knot *

* is a quandle cocycle invariant. *

* Further we will show that it completely determines invertibility and positive/negative*

* amphicheirality of hyperbolic knots. *