In this addendum-like text with just two references, an alternative,
graphical-method-inspired constructive re-derivation of some of the
results of paper [2] is offered. Although the subject itself (viz.,
the nonlinear Cauchy problem $y'(x) = cos[\pi xy(x)]$) carries
multiple apparently remarkable features (see also extended abstract
MR3216779), calling it (in a way inspired by some parallels with
certain elementary quantum systems) a ``nonlinear eigenvalue
problem'' seems exaggerated. A title like ``ordinary differential
equations with separatrices'' would probably fit the subject better.
MR3254850 (Sent 2014-12-10) Kerr, Oliver S. Comment on `Nonlinear
eigenvalue problems'. J. Phys. A 47 (2014), no. 36, 368001, 5 pp.
34A12 (34C15 34D05 34E20 34M55 37K10)
.