On the classification of planar constrained differential systems under topological equivalence

This paper concerns the local study of analytic constrained differential systems (or impasse systems) of the form $A(x)\dot{x}=F(x)$, $x\in {\mathbb{R}}^2$, where $F$ is a vector field and $A$ is a matrix valued function. Using techniques of resolution of singularities with weighted blow ups, we extend well-known results in the literature on topological classification of phase portraits of planar vector fields to the context of such class of systems. We also study and classify phase portraits of constrained systems near singular points of the so called impasse set $\mathrm{\Delta }=\{x:\det A(x)=0\}$.