Krasinkiewicz spaces and parametric Krasinkiewicz maps

TL;DR

This paper studies Krasinkiewicz spaces, showing that under certain conditions, the space of maps into these spaces contains a dense set of Krasinkiewicz maps with desirable properties.

Contribution

It establishes that for perfect maps between metrizable spaces, the function space contains a dense G_delta set of Krasinkiewicz maps, extending previous understanding of these spaces.

Findings

Dense G_delta subset of Krasinkiewicz maps in function space

Extension of results to spaces homeomorphic to convex subsets of Banach spaces

Applicable to perfect maps with countable union of finite-dimensional subsets

Abstract

We say that a metrizable space $M$ is a Krasinkiewicz space if any map from a metrizable compactum $X$ into $M$ can be approximated by Krasinkiewicz maps (a map $g\colon X\to M$ is Krasinkiewicz provided every continuum in $X$ is either contained in a fiber of $g$ or contains a component of a fiber of $g$). In this paper we establish the following property of Krasinkiewicz spaces: Let $f\colon X\to Y$ be a perfect map between metrizable spaces and $M$ a Krasinkiewicz complete $ANR$-space. If $Y$ is a countable union of closed finite-dimensional subsets, then the function space $C(X,M)$ with the source limitation topology contains a dense $G_{\delta}$-subset of maps $g$ such that all restrictions $g|f^{-1}(y)$, $y\in Y$, are Krasinkiewicz maps. The same conclusion remains true if $M$ is homeomorphic to a closed convex subset of a Banach space and $X$ is a $C$-space.