\(QS11_{16}^{(2)}\)

Description

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

Phase Portrait

Topological Invariants

TCSP	Fin Sep	Inf Sep
\(11\)	\(4411\)	\(3221\)

Example

The quadratic differential system

\[\begin{cases} \dot{x} = ce + x^{2} + 2 \, ch \, x \, y + (-1 - 2 \, ch + cn) \, y^{2} \\ \dot{y} = cl \, x^{2} + y + 2 \, (1 + ch - cl - cn/2) \, x \, y + (-2 - 2 \, ch + cl + 2 \, cn) \, y^{2} \end{cases}\]

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 \(BD48\) in {J. C. Artés}, Systems of class BD, {Preprint} (2026).