Isolated singularities of binary differential equations of degree $n$

T. Fukui, J. J. Nuño-Ballesteros
2012 Publicacions matemàtiques  
We study isolated singularities of binary differential equations of degree n which are totally real. This means that at any regular point, the associated algebraic equation of degree n has exactly n different real roots (this generalizes the so called positive quadratic differential forms when n = 2). We introduce the concept of index for isolated singularities and generalize Poincaré-Hopf theorem and Bendixson formula. Moreover, we give a classification of phase portraits of the n-web around a
more » ... generic singular point. We show that there are only three types, which generalize the Darbouxian umbilics D 1 , D 2 and D 3 .
doi:10.5565/publmat_56112_03 fatcat:ltfuu5og25honbbimfqnftl7gu