Verallgemeinerung eines Satzes von Jacobi und Scherrer.
An elementary stabilization of a Legendrian knot L in the spherical cotangent bundle ST*M of a surface M is a surgery that results in attaching a handle to M along two discs away from the image in M of the projection of the knot L. A virtual Legendrian isotopy is a composition of stabilizations, destabilizations and Legendrian isotopies. A class of virtual Legendrian isotopy is called a virtual Legendrian knot. In contrast to Legendrian knots, virtual Legendrian knots enjoy the...
Properties of enveloping helicoidal surfaces, generated by helicoidal movement of developable line surfaces, are treated. A construction is given of the characteristic of an enveloping helicoidal surface, of its axial sections, of its sections by planes perpendicular to the axis of helicoidal movement, and ot the plane tangent to a characteristic at a general point of the surface.
Let be the interior of a compact manifold of dimension with boundary , and be a conformally compact metric on , namely extends continuously (or with some degree of smoothness) as a metric to , where denotes a defining function for , i.e. on and , on . The restrction of to rescales upon changing , so defines invariantly a conformal class of metrics on , which is called the conformal infinity of . In the present paper, the author considers conformally compact metrics...