A geometric characterisation of two-parameter spatial motions with many locally one-dimen\-sional point paths (Q1826674)

The authors study two-parametric motions of the Euclidean 3-space. Under such a motion any point of the moving space moves along a naturally parameterized surface. This parameterization can be singular. The authors give a differential geometric characterization of locally singular points on such surfaces and of two-parametric motions with a one-parametric family of locally singular point paths.