SAJI Kentaro

J-GLOBAL         Last updated: Sep 18, 2019 at 02:42
SAJI Kentaro
Kobe University
Graduate School of Science Division of Mathematics
Job title
Associate Professor

Research Areas


Published Papers

M. Kokubu, ROSSMAN FREMONT Wayne, Kentaro SAJI, M. Umehara, K. Yamada,
Pacific J. Math   294(2) 505-509   Feb 2018   [Refereed]
L. Martins, Kentaro SAJI
Topology Appl   234 209-219   Feb 2018   [Refereed]
Fold singularities on spacelike CMC surfaces in Lorentz-Minkowski space
A. Honda, M. Koiso, Kentaro SAJI
Hokkaido Math. J   47(no.2) 245-267   2018   [Refereed]
Normal form of the swallowtail and its applications
Kentaro SAJI
Internat. J. Math   29(no.7) 1850046,17 pp   2018   [Refereed]
On pairs of geometric foliations on a cuspidal edge. Singularities in generic geometry
Kentaro SAJI
Adv. Stud. Pure Math.   78 411-429   2018   [Refereed]
On the geometry of folded cuspidal edges
R. Oset Sinha, Kentaro SAJI
Rev. Mat. Complut   31(no.3) 627-650   2018   [Refereed]
An index formula for a bundle homomorphism of the tangent bundle into a vector bundle of the same rank, and its applications
SAJI Kentaro, M. Umehara, K. Yamada
J. Math. Soc. Japan   69(1) 417–457   Jan 2017   [Refereed]
Flat surfaces along cuspidal edges
S. Izumiya, Kentaro SAJI, N. Takeuchi
J. Singul   16 73-100   2017   [Refereed]
L. F. Martins, SAJI Kentaro, M. Umehara, K. Yamada
Geometry and topology of manifolds,SpringerProc. Math. Stat.   154 247-281   2016   [Refereed]
Criteria for Morin singularities for maps into lower dimensions, and applications
SAJI Kentaro
Real and complex singularities,Contemp. Math.,Amer. Math. Soc.,Providence, RI   675 315–336   2016   [Refereed]
Criteria for Morin singularities into higher dimensions
SAJI Kentaro
RIMS Kôkyûroku Bessatsu   B55 203--222.   2016   [Refereed]
Extensions of Koenderink’s formula
T. Fuku, M. Hasegawa, SAJI Kentaro
Journal of Gökova Geometry Topology   10    2016   [Refereed]
Martins Luciana, SAJI Kentaro
Canadian J. Math.   68(2) 445-462   2016   [Refereed]
Hasegawa, Masaru, Honda Atsufumi, Naokawa, Kosuke, SAJI Kentaro, Umehara, Masaaki, Yamada Kotaro
Internat. J. Math.   26(4)    2015   [Refereed]
SAJI Kentaro, Handan Yıldırım.
Ann. Polon. Math.   115(3) 241-261   2015   [Refereed]
FUJIMORI Shoichi, NORO Masayuki, SAJI Kentaro, SASAKI Takeshi, Yoshida Masaaki
Internat. J. Math.   26(6)    2015   [Refereed]
CHEN Liang, IZUMIYA Syuichi, Pei,Dong He, Saji Kentaro
Sci. China Math.   57(9) 1841-1866   2014   [Refereed]
Saji Kentaro
J. Singul.   10 264-270   2014   [Refereed]
Kentaro Saji, Masaaki Umehara, Kotaro Yamada
J. Geom. Anal   22(2) 383-409   Apr 2012   [Refereed]
Izumiya Shyuichi, Nagai Takayuki, Saji Kentaro
Differential Geom. Appl.   29(3) 409-425   2011   [Refereed]
Kentaro Saji, Masaaki Umehara, Kotaro Yamada
C. R. Math. Acad. Sci. Paris   348(11-12) 665-668   Jan 2010   [Refereed]
We prove that the difference between the numbers of positive swallowtails and negative swallowtails of the Blaschke normal map for a given convex surface in affine space is equal to the Euler number of the subset where the affine shape operator...
Kentaro Saji
J. Gökova Geom. Topol.      2010   [Refereed]
We give useful criteria for S_1 singularities in the Mond classification table, and cuspidal S_k singularities. As applications, we give a simple proof of a result given by Mond and a characterization of cuspidal S_k singularities for the compo...
The mandala of Legendrian dualities for pseudo-spheres in Lorentz-Minkowski space and ``flat'' spacelike surfaces
Shyuichi Izumiya, Kentaro Saji
J. Singul.   2 92-127   2010   [Refereed]
Kentaro Saji, Masaaki Umehara, Kotaro Yamada
   Oct 2009
We give a definition of `front bundles', which is an intrinsic formulation of wave fronts. In our definition of front bundles, the first fundamental forms and the third fundamental forms are considered as induced metrics of certain homomorphisms b...
Kentaro Saji
Tohoku Math. J.      Jun 2009   [Refereed]
We give useful and simple criteria for determining Tex singularities of wave fronts. As an application, we investigate behaviors of singular curvatures of cuspidal edges near Tex singularities.
Kentaro Saji
Hiroshima Math. J.      May 2009   [Refereed]
We shall give useful criteria of lips, beaks and swallowtail singularities of smooth map from the plane into the plane. As an application of criteria, we will discuss the singularities of Cauchy problem of single conservation law.
Kentaro Saji, Masaaki Umehara, Kotaro Yamada
Math. Proc. Camb. Philos. Soc.   146(3) 731-746   2009   [Refereed]
In this paper, we discuss the recognition problem for A_k-type singularities on wave fronts. We give computable and simple criteria of these singularities, which will play a fundamental role in generalizing the authors' previous work "the geome...
Kentaro Saji
数理解析研究所講究録   1610 114-120   Aug 2008
Shoichi Fujimori, Kentaro Saji, Masaaki Umehara, Kotaro Yamada
Math. Z.   259(4) 827-848   2008   [Refereed]
We show that the singularities of spacelike maximal surfaces in Lorentz-Minkowski 3-space generically consist of cuspidal edges, swallowtails and cuspidal cross caps. The same result holds for spacelike mean curvature one surfaces in de Sitter ...

Books etc

梅原雅顕, Kentaro SAJI, 山田光太郎
丸善出版   Dec 2017   

Conference Activities & Talks

Kentaro SAJI
日本数学会トポロジー分科会   Mar 2019   
Singularities of wave fronts and curvatures [Invited]
Kentaro SAJI
幾何学的視点からの形状形成   Sep 2018   
SO(3) normal forms and differential geometric invariants of singular surfaces [Invited]
Kentaro SAJI
15th edition of the International Workshop on Real and Complex Singularities, Instituto de Ciências Matemáticas e de Computacão   Jul 2018   
Singular surfaces with prescribed unbounded mean curvature
Kentaro SAJI
微分幾何学・微分式系・特異点論の応用   Jun 2018   
Singular surfaces of revolution with prescribed unbounded mean curvature
Kentaro SAJI
第7回神戸特異点研究会   Mar 2018   

Research Grants & Projects

singularity theory
Project Year: 1999 - 2100
Voronoi diagrams and its application
Differential geometry of wave fronts