Hans-Otto Walther 
$2$-Dimensional Attractor of $x'(t)=-{/mu } x(t) + f(x(t-1))$ [PDF ebook] 

The equation $x'(t) = – /mu x(t) + f(x(t-1))$, with $/mu /geq 0$ and $xf(x) /le 0$ for $0/neq x/in {/mathbb R}$, is a prototype for delayed negative feedback combined with friction. Its semiflow on $C=C([-1, 0], {/mathbb R})$ leaves a set $S$ invariant, whi