Symbolic Computations of First Integrals for Polynomial Vector Fields

In this article we show how to generalize to the Darbouxian, Liouvillian and Riccati case the extactic curve introduced by J. Pereira. With this approach, we get new algorithms for computing , if it exists, a rational, Darbouxian, Liouvillian or Riccati first integral with bounded degree of a polynomial planar vector field. We give probabilistic and deterministic algorithms. The arithmetic complexity of our probabilistic algorithm is in O(N ^{$\omega$+1}), where N is the bound on the degree of a representation of the first integral and $\omega$ $\in$ [2; 3] is the exponent of linear algebra. This result improves previous algorithms.