The influence of the integral manifold shape on the onset of relaxation oscillations

The relaxation oscillations are studied of a singularly perturbed system of ordinary differential equations with m slow and n fast variables (m × n) in the two cases: (1) m = n = 1 (1 × 1) and (2) m = 2, n = 1 (2 × 1). As sufficient conditions for the existence of relaxation oscillations there some general class is described of the functions determining the slow manifold for this system.