Binary differential equations (that is, equations of the form a (x, y) dy²+2b (x, y) dx dy+c (x, y) dx²=0, where the coefficients a, b and c are analytic functions in a neighbourhood of the point (0, 0) ) are considered. A rigidity theorem is proved for degenerate singular points of such equations (that is, for a (0, 0) =b (0, 0) =c (0, 0) =0): if two generic binary differential equations of this form are formally equivalent, then they are analytically equivalent. Bibliography: 36 titles.
Воронин et al. (Wed,) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: