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Sharkovskii’s theorem, differential inclusions, and beyond. (English) Zbl 1189.34028

Authors’ abstract: We explain why the Poincaré translation operators along the trajectories of upper-Carathéodory differential inclusions do not satisfy the exceptional cases, described in our earlier counter-examples, for upper semicontinuous maps. Such a discussion was stimulated by a recent paper of F. Obersnel and P. Omari, where they show that, for Carathéodory scalar differential equations, the existence of just one subharmonic solution (e.g. of order 2) implies the existence of subharmonics of all orders. We reprove this result alternatively just via a multivalued Poincaré translation operator approach. We also establish its randomized version on the basis of a universal randomization scheme developed recently by the first author.

MSC:

34A60 Ordinary differential inclusions
37E15 Combinatorial dynamics (types of periodic orbits)
37H10 Generation, random and stochastic difference and differential equations
47H04 Set-valued operators
47H40 Random nonlinear operators
34C05 Topological structure of integral curves, singular points, limit cycles of ordinary differential equations
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