On generalized iterated function systems defined on $\ell_\infty$-sum of a metric space

Abstract: Miculescu and Mihail in 2008 introduced a concept of a generalized iterated function system (GIFS in short), a particular extension of classical IFS. Instead of families of selfmaps of a metric space $X$, they considered families of mappings defined on finite Cartesian product $X<sup>m$. It turned out that a great part of the classical Hutchinson--Barnsley theory has natural counterpart in this GIFSs' case. Recently, Secelean extended these considerations to mappings defined on the space $\ell_\infty(X)$ of all bounded sequences of elements of $X$ and obtained versions of the Hutchinson--Barnsley theorem for appropriate families of such functions. In the paper we study some further aspects of Secelean's setting. In particular, we introduce and investigate a bit more restrictive framework and we show that some problems of the theory have more natural solutions within such a case. Finally, we present an example which shows that this extended theory of GIFSs gives us fractal sets that cannot be obtained by any IFSs or even by any GIFSs.%In a paper of the authors and Jachymski we itroduced fixed point theory for mappings defined on $\ell_\infty(X)$ product of a metric space $X$. In this note we use this approach to study a version of Hutchinson--Barnsley theory of fractals for function systems consisting of such mappings. In particular, we generalize the earlier concept of generalized generated function systems introduced by Mihail and Miculescu in 2008, in which mappings defined on finite Cartesian product are considered, and compare our approach with the one introduced recently by Secelean.