We present a series of polynomial planar vector fields without algebraic invariant curves in $C{P}^2$.

In this paper we consider cubic polynomial systems of the form: x' = y + P(x, y), y' = −x + Q(x, y), where P and Q are polynomials of degree 3 without linear part. If M(x, y) is an integrating factor of the system, we propose its reciprocal V (x, y) = 1 / M(x,y) as a linear function of certain coefficients of the system. We find in this way several new sets of sufficient conditions for a center. The resulting integrating factors are of Darboux type and the first integrals are in the Liouville form.By...

Let $\gamma$ be an integral solution of an analytic real vector field $\xi$ defined in a neighbordhood of $0\in {ℝ}^3$. Suppose that $\gamma$ has a single limit point, $\omega \left(\gamma \right)=\left\{0\right\}$. We say that $\gamma$ is non oscillating if, for any analytic surface $H$, either $\gamma$ is contained in $H$ or $\gamma$ cuts $H$ only finitely many times. In this paper we give a sufficient condition for $\gamma$ to be non oscillating. It is established in terms of the existence of “generalized iterated tangents”, i.e. the existence of a single limit point for any transform property for...

In this paper we consider complex differential systems in the plane, which are linearizable in the neighborhood of a nondegenerate centre. We find necessary and sufficient conditions for linearizability for the class of complex quadratic systems and for the class of complex cubic systems symmetric with respect to a centre. The sufficiency of these conditions is shown by exhibiting explicitly a linearizing change of coordinates, either of Darboux type or a generalization of it.

$C^{\infty }$ normal forms are given for singularities of $C^{\infty }$ vectorfields on $\mathbf{R}$, which are not flat, and for $C^{\infty }$ vectorfields $X$ on ${\mathbf{R}}^2$ with $X\left(0\right)=0$, the 1-jet of $X$ in the origin is a pure rotation, and some higher order jet of $X$ attracting or expanding.