Relaxations in Singularly Perturbed Planar Systems

The relaxation oscilations and canard-solutions are studied in the system of singularly perturbed differential equations with one slow and one fast variables. The analysis is based on using classical mathematics, i.e., without elements of nonstandard analysis.
The sufficient condition is presented for the fact that the relaxational oscillation is the limit position of the canard set as the repelling part of the slow manifold tends to zero.