Figure 2

Reduced dynamics (4) on the critical manifold (6), and its projection onto the v–p plane, together with the lines of folds \(F_{l}\), \(F_{h}\) and their projections \(P_{l}\), \(P_{h}\). A saddle point and its stable (blue) and unstable (red) manifolds in the reduced system are shown on the critical manifold. The black trajectory is a singular relaxation oscillation composed of two slow parts (single arrow) connected by two trajectories along fast fibers (double arrow, dotted in the projection)