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On points of lower and upper quasi-continuity of multivalued maps. (English) Zbl 0637.54016

The author studies upper (lower) quasi-continuous multifunctions from a topological space X to a metric one (Y,d). The main result is that if X is extremally disconnected and F is a lower quasi-continuous multifunction with compact values, then the set of the points at which F is not upper quasi-continuous is a set of the first category.
Reviewer: M.B.Lignola

MSC:

54C60 Set-valued maps in general topology
54C08 Weak and generalized continuity
54F05 Linearly ordered topological spaces, generalized ordered spaces, and partially ordered spaces
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References:

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