On approximation by functions having strong entropy point

Ewa Korczak-Kubiak, Ryszard J. Pawlak

Abstract


The paper deals with approximation of functions from the unit interval into itself by means of functions having strong entropy point. For this purpose we define a family of functions having the fixed point property: $Conn_C$ (which is a subfamily of the class $Conn$ introduced in [16]). The main result of the paper is a theorem saying that for any function $f\in Conn_C$ and any point $x_0 \in Fix(f)$ there exist
a ring $R \subset Conn_C$ containing function $ f$ and in the intersection of any "graph
neighbourhood of f" and "neighbourhood of f in topology of uniform convergence"
one can find functions $\xi, \psi  \in R$ having strong entropy point $y_0$ located close to the
point $x_0$ and being a discontinuity point of the function $\xi$ and a continuity point of
the function \psi.

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DOI: https://doi.org/10.2478/tatra.v58i0.263