Sets of locally maximal visibility and finite unions of starshaped sets

Authors
Citation
M. Breen, Sets of locally maximal visibility and finite unions of starshaped sets, MONATS MATH, 130(1), 2000, pp. 1-5
Citations number
4
Categorie Soggetti
Mathematics
Journal title
MONATSHEFTE FUR MATHEMATIK
ISSN journal
00269255 → ACNP
Volume
130
Issue
1
Year of publication
2000
Pages
1 - 5
Database
ISI
SICI code
0026-9255(2000)130:1<1:SOLMVA>2.0.ZU;2-D
Abstract
Let S = cl(intS), where intS is an open connected subset of some linear top ological space, such that S contains all triangular regions whose (relative ) boundaries lie in S. If some finite subset Tof S has locally maximal visi bility in S, then V-T = S. Hence S is a finite union of starshaped sets who se kernels are determined by T. An analogous result holds for S open. Moreo ver, counterexamples show that neither the requirement on triangular region s nor the restriction to a finite set T can be deleted.