A Second look at the first result of Landesman-Lazer type

Abstract

We discuss some results concerning periodic and almot periodic solutions of ordinary differential equations which are precursors of a result on weak solutions of a semilinear elliptic boundary due to E. M. Landesman and the author. It is observed that in the earliest of these, if one looks for periodic solutions instead of almost peridic solutions, then the conditions can be relaxed.

Keywords

• Globally asymptotically stable
• Brouwer fix-point theorem
• polar coordinates.