The asymmetry on singularities of tangent surfaces in contact-cone Legendre-null duality

Abstract

We give the generic classification on singularities of tangent surfaces to Lengendre curves and to null curves by using the contact-cone duality between the contact 3-sphere and the Lagrange-Grassmannian with cone structure of a symplectic 4-space. As a consequence, we observe that the symmetry on the lists of such singularities is breaking for the contact-cone duality, compared with the ordinary projective duality.