Autor:	Ribarska, Nadezhda K.
Zdroj:	Mathematika; June 1998, Vol. 45 Issue: 1 p113-118, 6p
Abstrakt:	Let Xbe a Hausdorff topological space and let ? be a metric on it, not necessarily related to the topology. The space Xis said to be fragmentedby the metric ? if each nonempty set in Xhas nonempty relatively open subsets of arbitrary small ?-diameter. This concept was introduced by Jayne and Rogers (see [2]) while they studied the existence of Borel selections for upper semicontinuous set-valued maps.
Databáze:	Supplemental Index
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