Cyclicity near infinity in piecewise linear vector fields having a nonregular switching line (Q6157804)

In this paper the authors consider the number of limit cycles of planar piecewise linear systems with the switch manifolds \[ \{x=0, y>0\} \cup \{y=0, x>0\}. \] After a careful analysis, the authors show that at least five limit cycles bifurcate from infinity. It is worth pointing out that the same number of limit cycles has been obtained by a Melnikov analysis of high order.