Kuratowski Chains
نویسندگان
چکیده
منابع مشابه
Kuratowski Complexes
AN n-dimensional simplicial complex K. n 2 I, which does not embed in R*“, is said to be minimally non-tvd~ddable in W’” if all proper subspaces of the same are embeddable in l&F*“. The well known planarity criterion of Kuratowski [6], 1930. tells us that, for n = I, there are. upto homeomorphism. only two such simplicial complexes, 0: and rr,$&$ (Here, and below, c$ denotes the j-skeleton of a...
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Proof. Let us assume that G is planar but not free planar. Then there exists an edge xy not belonging to the graph whom adding to the graph it becomes non-planar. Then in G for an arbitrary cycle C through x, y there exists a pair of screening bridges Bx and By x from y with respect to C, i. e. either Bx and By are not placeable on one side against C or they are connected [i.e. not placeable to...
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In the paper we give formal descriptions of the two Kuratowski limit oprators: Li S and Ls S, where S is an arbitrary sequence of subsets of a fixed topological space. In the two last sections we prove basic properties of these lower and upper topological limits, which may be found e.g. in [19]. In the sections 2–4, we present three operators which are associated in some sense with the above me...
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متن کاملOn the Kuratowski Limit Operators1
In the paper we give formal descriptions of the two Kuratowski limit oprators: Li S and Ls S, where S is an arbitrary sequence of subsets of a fixed topological space. In the two last sections we prove basic properties of these lower and upper topological limits, which may be found e.g. in [19]. In the sections 2–4, we present three operators which are associated in some sense with the above me...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series B
سال: 1995
ISSN: 0095-8956
DOI: 10.1006/jctb.1995.1030