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Various aspects on the study of Geometric Function Theory

Research Project

Project/Area Number 22340025
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Basic analysis
Research InstitutionTohoku University

Principal Investigator

SUGAWA Toshiyuki  東北大学, 情報科学研究科, 教授 (30235858)

Co-Investigator(Kenkyū-buntansha) SHIGA Hiroshige  東京工業大学, 理工学研究科, 教授 (10154189)
YANAGIHARA Hiroshi  山口大学, 理工学研究科, 教授 (30200538)
SAKAN Ken-ichi  大阪市立大学, 理学研究科, 准教授 (70110856)
MATSUZAKI Katsuhiko  早稲田大学, 教育・総合科学学術院, 教授 (80222298)
FUJIKAWA Ege  千葉大学, 理学研究科, 准教授 (80433788)
阿部 誠  広島大学, 大学院・理学研究科, 教授 (90159442)
水田 弘  広島大学, 大学院・理学研究科, 教授 (00093815)
Co-Investigator(Renkei-kenkyūsha) MIZUTA Yoshihiro  広島工業大学, 工学部, 教授 (00093815)
TANIGUCHI Masahiko  奈良女子大学, 理学部, 教授 (50108974)
FUJIWARA Koji  京都大学, 理学研究科, 教授 (60229078)
ABE Makoto  広島大学, 理学研究科, 教授 (90159442)
Project Period (FY) 2010-04-01 – 2015-03-31
Project Status Completed (Fiscal Year 2014)
Budget Amount *help
¥17,290,000 (Direct Cost: ¥13,300,000、Indirect Cost: ¥3,990,000)
Fiscal Year 2014: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2013: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2012: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2011: ¥3,120,000 (Direct Cost: ¥2,400,000、Indirect Cost: ¥720,000)
Fiscal Year 2010: ¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Keywords等角写像 / 単葉函数 / 双曲計量 / 錐特異性 / シュワルツ微分 / 極値問題 / 擬等角写像 / 一様完全 / 面積不等式 / 幾何学的函数論 / 変動領域 / 単葉性判定法 / シュワルツ補題 / ベキ変形 / グルンスキー係数 / ベキ行列 / 退化ベルトラミ方程式 / 半円環
Outline of Final Research Achievements

Geometric Function Theory deals with problems finding relations between geometrically described (simply-connected) domains in the plane and analytic properties of conformal mappings onto them. Bieberbach conjectured that, for a conformal mapping f(z)=a_0+a_1z+a_2z^2+... normalized by a_0=0, a_1=1, the modulus |a_n| of a_n is not greater than n.This conjecture was finally proved by de Branges in his 1985 paper. In the present research project, for example, we showed that the set of conformal mappings as above with half-integral coefficients consists of exactly 21 functions. The similar set for the integral coefficients was previously known to consist of 9 functions.

Report

(6 results)
  • 2014 Annual Research Report   Final Research Report ( PDF )
  • 2013 Annual Research Report
  • 2012 Annual Research Report
  • 2011 Annual Research Report
  • 2010 Annual Research Report
  • Research Products

    (36 results)

All 2015 2014 2013 2012 2011 2010 Other

All Journal Article (18 results) (of which Peer Reviewed: 17 results,  Acknowledgement Compliant: 3 results) Presentation (17 results) (of which Invited: 8 results) Book (1 results)

  • [Journal Article] Spherical density of hyperbolic metric and uniform perfectness2015

    • Author(s)
      Toshiyuki Sugawa
    • Journal Title

      Journal of Analysis

      Volume: 21 Pages: 159-168

    • Related Report
      2014 Annual Research Report
    • Acknowledgement Compliant
  • [Journal Article] Variability regions of close-to-convex functions2014

    • Author(s)
      Takao Kato, Toshiyuki Sugawa and Li-Mei Wang
    • Journal Title

      Ann. Polon. Math.

      Volume: 111 Issue: 1 Pages: 89-105

    • DOI

      10.4064/ap111-1-7

    • Related Report
      2014 Annual Research Report
    • Peer Reviewed / Acknowledgement Compliant
  • [Journal Article] Radius problems associated with pre-Schwarzian and Schwarzian derivatives2014

    • Author(s)
      S. Ponnusamy, S. K. Sahoo and T. Sugawa
    • Journal Title

      Analysis

      Volume: 34 Issue: 2 Pages: 163-171

    • DOI

      10.1515/anly-2012-1219

    • Related Report
      2014 Annual Research Report
    • Peer Reviewed / Acknowledgement Compliant
  • [Journal Article] Univalent functions with half-integral coefficients2013

    • Author(s)
      Naoki Hiranuma and Toshiyuki Sugawa
    • Journal Title

      Computational Methods and Function Theory

      Volume: 13 Issue: 1 Pages: 133-151

    • DOI

      10.1007/s40315-013-0009-z

    • Related Report
      2013 Annual Research Report
    • Peer Reviewed
  • [Journal Article] On μ-conformal homeomorphisms and boundary correspondence2013

    • Author(s)
      Vladimir Gutlyanskii, Ken-ichi Sakan, Toshiyuki Sugawa
    • Journal Title

      Complex Var. Elliptic Equ.

      Volume: 58 Issue: 7 Pages: 947-962

    • DOI

      10.1080/17476933.2011.613116

    • Related Report
      2013 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Univalence criteria and analogs of the John constant2013

    • Author(s)
      Yong Chan Kim, Toshiyuki Sugawa
    • Journal Title

      Bull. Austr. Math. Soc.

      Volume: 88 Issue: 3 Pages: 423-434

    • DOI

      10.1017/s0004972712000962

    • Related Report
      2013 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Quasiconformal extension of strongly spirallike functions2012

    • Author(s)
      T. Sugawa
    • Journal Title

      Comput. Methods Func. Theory

      Volume: 12 Pages: 19-30

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Correspondence between spirallike functions and starlike functions2012

    • Author(s)
      Y.C.Kim and T. Sugawa
    • Journal Title

      Math. Nachr.

      Volume: 285 Issue: 2-3 Pages: 322-331

    • DOI

      10.1002/mana.201010020

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] A Remark on Löwner's Theorem2012

    • Author(s)
      Y.C.Kim
    • Journal Title

      Interdisciplinary Information Sciences

      Volume: 18 Issue: 1 Pages: 19-22

    • DOI

      10.4036/iis.2012.19

    • NAID

      130001916205

    • ISSN
      1340-9050, 1347-6157
    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] On power deformations of univalent functions2012

    • Author(s)
      Y.C.Kim
    • Journal Title

      Monatsh. Math.

      Volume: 167 Issue: 2 Pages: 231-240

    • DOI

      10.1007/s00605-011-0344-y

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] On a multi-point Schwarz-Pick lemma2012

    • Author(s)
      Kyung Hyun Cho, Seong-A Kim and T. Sugawa
    • Journal Title

      Comput. Methods Func. Theory

      Volume: 12 Pages: 483-499

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] On univalence of the power deformation z(f(z)/z)^c2012

    • Author(s)
      Y. C. Kim and T. Sugawa
    • Journal Title

      Chinese Ann. Math., Ser. B

      Volume: 33 Issue: 6 Pages: 823-830

    • DOI

      10.1007/s11401-012-0750-z

    • Related Report
      2012 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Invariant Schwarzian derivatives of higher order2011

    • Author(s)
      S.A Kim, T.Sugawa
    • Journal Title

      Complex Analysis and Operator Theory

      Volume: 5 Issue: 3 Pages: 659-670

    • DOI

      10.1007/s11785-010-0081-6

    • Related Report
      2011 Annual Research Report
    • Peer Reviewed
  • [Journal Article] GEOMETRIC INVARIANTS ASSOCIATED WITH PROJECTIVE STRUCTURES AND UNIVALENCE CRITERIA2011

    • Author(s)
      S.A Kim, T.Sugawa
    • Journal Title

      Tohoku Mathematical Journal, Second Series

      Volume: 63 Issue: 1 Pages: 41-57

    • DOI

      10.2748/tmj/1303219935

    • NAID

      110008425968

    • ISSN
      0040-8735, 2186-585X
    • Related Report
      2011 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Metrics with conical singularities on the sphere and sharp extensions of the theorems of Landau and Schottky2011

    • Author(s)
      D.Klaus, O.Roth, T.Sugawa
    • Journal Title

      Math.Z.

      Volume: 267 Issue: 3-4 Pages: 851-868

    • DOI

      10.1007/s00209-009-0649-x

    • Related Report
      2011 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Hardy spaces and unbounded quasidisks2011

    • Author(s)
      Y.C.Kim, T.Sugawa
    • Journal Title

      Ann.Acad.Sci.Fenn.Math.

      Volume: 36 Pages: 41-57

    • Related Report
      2010 Annual Research Report
    • Peer Reviewed
  • [Journal Article] Twice-punctured hyperbolic sphere with a conical singularity and generalized elliptic integral2010

    • Author(s)
      Anderson, Sugawa, Vamanamurthy, Vuorinen
    • Journal Title

      Math.Z.

      Volume: 266 Pages: 181-191

    • Related Report
      2010 Annual Research Report
    • Peer Reviewed
  • [Journal Article] A conformally invariant metric on Riemann surfaces associated with integrable holomorphic quadratic differentials2010

    • Author(s)
      T.Sugawa
    • Journal Title

      Math.Z.

      Volume: 266 Pages: 645-664

    • Related Report
      2010 Annual Research Report
    • Peer Reviewed
  • [Presentation] An application of the Loewner theory to trivial Beltrami coefficients2014

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      International Workshop on Conformal Dynamics and Loewner Theory
    • Place of Presentation
      東京工業大学
    • Year and Date
      2014-11-22
    • Related Report
      2014 Annual Research Report
  • [Presentation] Extremal problems for close-to-convex functions2014

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      22nd ICFIDCAA
    • Place of Presentation
      Dongguk University, Korea
    • Year and Date
      2014-08-08
    • Related Report
      2014 Annual Research Report
  • [Presentation] Hyperbolic metric with conic singularities on Riemann surfaces and its applications2014

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      Workshop on Complex Geometry
    • Place of Presentation
      University of Hong Kong, Hong Kong
    • Year and Date
      2014-07-29
    • Related Report
      2014 Annual Research Report
    • Invited
  • [Presentation] Variability regions of log[f(z)/z] for a class of univalent functions with application to some extremal problems2014

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      Workshop on Analytic Functions and Applied Mathematics
    • Place of Presentation
      University of Rzeszow, Poland
    • Year and Date
      2014-07-04
    • Related Report
      2014 Annual Research Report
  • [Presentation] A note on trivial Beltrami coefficients2014

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      XVII-th Conference on Analytic Functions and Related Topics
    • Place of Presentation
      The State School of Higher Education in Chelm, Poland
    • Year and Date
      2014-06-30
    • Related Report
      2014 Annual Research Report
  • [Presentation] Power deformations of univalent functions2011

    • Author(s)
      T.Sugawa
    • Organizer
      The 19th ICFIDCAA
    • Place of Presentation
      広島アステールプラザ(招待講演)
    • Year and Date
      2011-12-14
    • Related Report
      2011 Annual Research Report
  • [Presentation] On boundary regularity of solutions to-degenerate Beltrami equations2010

    • Author(s)
      T.Sugawa
    • Organizer
      The 18th ICFIDCAA
    • Place of Presentation
      University of Macau, China
    • Year and Date
      2010-08-15
    • Related Report
      2010 Annual Research Report
  • [Presentation] Univalence criteria in terms of |zf'(z)/f(z)|

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      CMFT 2013
    • Place of Presentation
      Shantou University, China
    • Related Report
      2013 Annual Research Report
  • [Presentation] Hyperbolic metric on a Riemann surface with conical singularities

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      21th ICFIDCAA
    • Place of Presentation
      Nanjing University, China
    • Related Report
      2013 Annual Research Report
    • Invited
  • [Presentation] Hyperbolic metric on a Riemann surface with conical singularities

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      Analysis and Geometry of Riemann Surfaces and Related Topics
    • Place of Presentation
      東工大
    • Related Report
      2013 Annual Research Report
    • Invited
  • [Presentation] Schwarz-Christoffel formula for the exterior of a quadrangle

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      The 2nd Chinese-Finnish Seminar
    • Place of Presentation
      University of Turku, Finland
    • Related Report
      2013 Annual Research Report
    • Invited
  • [Presentation] Variability regions of close-to-convex functions

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      第2回RCPAM国際シンポジウム Geometric Function Theory and Applications in Sendai
    • Place of Presentation
      東北大学大学院情報科学研究科
    • Related Report
      2013 Annual Research Report
  • [Presentation] An attempt to characterize quasidisks in terms of zf'(z)/f(z)

    • Author(s)
      Toshiyuki Sugawa
    • Organizer
      Conference on Geometric Function Theory
    • Place of Presentation
      University of Belgrade, Serbia
    • Related Report
      2013 Annual Research Report
    • Invited
  • [Presentation] On power deformations of a univalent function

    • Author(s)
      T. Sugawa
    • Organizer
      International Conference on Complex Analysis and Related Topics
    • Place of Presentation
      Ploiesti, Romania
    • Related Report
      2012 Annual Research Report
  • [Presentation] Quasiconformal extension of strongly spirallike functions

    • Author(s)
      T. Sugawa
    • Organizer
      Satellite Thematic Session "Quasiconformal mappings and complex dynamical systems", in 6th European Congress of Mathematics
    • Place of Presentation
      Krakow, Poland
    • Related Report
      2012 Annual Research Report
    • Invited
  • [Presentation] Generalizations of the Schwarzian derivative

    • Author(s)
      T. Sugawa
    • Organizer
      20th ICFIDCAA
    • Place of Presentation
      Hanoi University of Science and Technology, Vietnam
    • Related Report
      2012 Annual Research Report
    • Invited
  • [Presentation] シュワルツ微分の一般化 ~不変化と高階化を目指して~

    • Author(s)
      須川敏幸
    • Organizer
      日本数学会函数論分科会特別講演
    • Place of Presentation
      九州大学
    • Related Report
      2012 Annual Research Report
    • Invited
  • [Book] Topics in Finite or Infinite Dimensional Complex Analysis2013

    • Author(s)
      K. Matsuzaki and T. Sugawa (eds),
    • Total Pages
      268
    • Publisher
      Tohoku University Press, Sendai
    • Related Report
      2012 Annual Research Report

URL: 

Published: 2010-08-23   Modified: 2019-07-29  

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