It is shown that the following hyperspaces, endowed with the Hausdorff metric, are true absolute -sets: (1) ℳ ²₁(X) of Sierpiński universal curves in a locally compact metric space X, provided ℳ ²₁(X) ≠ ∅ ; (2) ℳ ³₁(X) of Menger universal curves in a locally compact metric space X, provided ℳ ³₁(X) ≠ ∅ ; (3) 2-cells in the plane.
@article{bwmeta1.element.bwnjournal-article-doi-10_4064-cm91-1-7,
author = {Pawe\l\ Krupski},
title = {Hyperspaces of universal curves and 2-cells are true $F\_{$\sigma$$\delta$}$-sets},
journal = {Colloquium Mathematicae},
volume = {91},
year = {2002},
pages = {91-98},
zbl = {0980.54004},
language = {en},
url = {http://dml.mathdoc.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm91-1-7}
}
Paweł Krupski. Hyperspaces of universal curves and 2-cells are true $F_{σδ}$-sets. Colloquium Mathematicae, Tome 91 (2002) pp. 91-98. http://gdmltest.u-ga.fr/item/bwmeta1.element.bwnjournal-article-doi-10_4064-cm91-1-7/