منابع مشابه
Bottlenecks in Dendroids
A subcontinuum C of a dendroid X is a bottleneck if it intersects every arc connecting two nonempty open subsets of X. We prove that every dendroid has a point p contained in arbitrarily small bottlenecks. Moreover, every plane dendroid contains a single point bottleneck. This implies, for instance, that each map from an indecomposable continuum into a plane dendroid must have an uncountable po...
متن کاملA Collection of Dendroids
An uncountable collection of uniformly arcwise connected plane Suslinian dendroids is constructed which shows that the negations of the following properties: local connectedness, smoothness, pointwise smoothness, hereditary contractibility, and selectibility are not countable in this class of
متن کاملMapping Chainable Continua onto Dendroids
We prove that every chainable continuum can be mapped into a dendroid such that all point-inverses consist of at most three points. In particular, it follows that there exists a finite-to-one map from a hereditarily indecomposable continuum (the pseudoarc) onto hereditarily decomposable continuum. This answers a question by J. Krasinkiewicz.
متن کاملPopulation bottlenecks
What are they? They occur when a wild population is reduced to a small number of individuals, and then increases again. They are typically caused by an environmental change such as unusual climatic conditions, or, increasingly, the actions of humans, as in over-hunting and habitat destruction. But if the population size is restored, everything ends up fine, surely? No. The small population size...
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ژورنال
عنوان ژورنال: Topology and its Applications
سال: 2003
ISSN: 0166-8641
DOI: 10.1016/s0166-8641(02)00159-1