\(QS11_{4}^{(2)}\)

Description

Topological configuration of singularities: \(s,s,a,a;N,(0,2)SN\)

Phase Portrait

Topological Invariants

TCSP	Fin Sep	Inf Sep
\(11\)	\(4421\)	\(3211\)

Example

The quadratic differential system

\[\begin{cases} \dot{x} = ce + x^{2} - (79 \, x \, y)/50 + (31 \, y^{2})/50 \\ \dot{y} = cl \, x^{2} + y + 2 \, (19/100 - cl) \, x \, y + (-17/50 + cl) \, y^{2} \end{cases}\]

has the following phase portrait done with P4. If you want, you may download the P4 file here.

The phase portrait appears in the following papers

With name \(BD33\) in {J. C. Artés}, Systems of class BD, {Preprint} (2026).