O projektivní geometrii
O trojúhelnících vzájemně vepsaných a opsaných
On a generalized stereographic projection. (Zur verallgemeinerten stereographischen Projektion.)
On permutable quadratic inversions in plane with two common singular points
On the matrices of central linear mappings
We show that a central linear mapping of a projectively embedded Euclidean -space onto a projectively embedded Euclidean -space is decomposable into a central projection followed by a similarity if, and only if, the least singular value of a certain matrix has multiplicity . This matrix is arising, by a simple manipulation, from a matrix describing the given mapping in terms of homogeneous Cartesian coordinates.