The cost of so many bound journals is becoming prohibitive. Consequently, many libraries are finding it necessary to cancel subscriptions. Thus, many papers published today may be largely unavailable to those wishing to read them. This journal will be free to anyone with e-mail or internet capabilities. Space for monographs and bound journals is becoming scarce in many libraries.
Electronic journals require little space.
And last, but by no means least, qualitative theory of differential equations has played a central role in pure and applied mathematics since the publication of the fundamental papers of Liapunov and Poincar . We believe it will continue to do so for a very long time. Thus, it seems well worth the effort to encourage research in this area and to disseminate the best results freely and to as wide an audience as possible. We hope you find the arguments convincing and will join the endeavor by contributing a paper. This book is an outgrowth of a course which we have given almost periodically over the last eight years.