- Published 2004

Let C: L L be a projective deformation of the second order of two totally pn focal pseudocongruences L and L of (m-l)-planes in projective spaces and n, 2m-i < n < 3m-l, and let K be a collineation realizing such a C. The deformation C is said to be weakly singular, singular, or a-strongly singular, s 3,4,..., if the collineation K gives projective deformations of order i, 2 or of all corresponding focal surfaces of L and L. It is proved that C is weakly singular and conditions are found for C to be singular. The pseudocongruences L and L are identical if and only f C is 3-strongly singular.

@inproceedings{Goldberg2004OnSP,
title={On Singular Projective Deformations of Two Second Class Totally Focal Pseudocongruences of Planes},
author={L Goldberg},
year={2004}
}