5 papers
Geometry on principal curvature surfaces
Luciana F. Martins, Kentaro Saji, Samuel P. dos Santos +1
We study the geometry of the principal curvature surface associated with a Whitney umbrella. This surface is obtained by extending the Whitney umbrella in the normal direction by i…
Geometry of -front singularities and a Gauss-Bonnet type formula
Kentaro Saji
We construct a form of the -singularity of fronts in which uses coordinate transformation on the source and isometry on the target. As an application, we compute diff…
Geometry of pseudo-non-degenerate two-ruled hypersurfaces
Junzhen Li, Kentaro Saji
We investigate the singularities of two-ruled hypersurfaces in the Euclidean four-space. By considering the points that minimize the distance between adjacent rulings, we obtain a…
Criteria for codimension two singularities of surfaces and their applications
Kentaro Saji, Runa Shimada
We give simple criteria for the singularities appearing on surfaces codimension less than or equal to two. As applications, we give conditions for codimension two singularities tha…
Singularities of helicoidal surfaces of frontals in the Euclidean space
N. Nakatsuyama, K. Saji, R. Shimada +1
We investigate helicoidal (screw) surfaces generated not only by regular curves but also by curves with singular points. For curves with singular points, it is useful to use fronta…