2 papers
math.DG2025
Geometry on ruled surfaces with finite multiplicity
Hiroyuki Hayashi
We consider ruled surfaces with finite multiplicity. We study behaviors of the striction curves and the singularities of the ruled surfaces. We also give geometric meanings of inva…
math.DG2024
Geometry of curves passing through Whitney umbrella
Hiroyuki Hayashi
We study geometry of curves passing through a Whitney umbrella by using a Darboux frame along it. We define three invariants by using Frenet-Serre type formula relating to the geod…