In this paper we give a
classification of simple stable singularities of Lagrange projections of the first open
Whitney umbrella, the simplest singularity of Lagrange varieties. Our classification
extends the ADE-classification, due to Arnold, of simple stable singularities
of Lagrange projections of smooth Lagrange submanifolds. We also prove
a criterion of equivalence of stable Lagrange projections of open Whitney
umbrellas which is analogous to Mather’s fundamental theorem on stable
map-germs.