Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userThe hyperspace of noncut subcontinua of some dendrites
48
0
0.0
(
0
)
Added by
Rodrigo Hern\\'andez Guti\\'errez
Publication date
2021
fields
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
The Vietoris hyperspace $NC^{*}(X)$ of noncut subcontinua of a metric continuum $X$ has been previously studied by several authors. In this paper we prove that if $X$ is a dendrite and the set of endpoints of $X$ is dense, then $NC^{*}(X)$ is homeomorphic to the Baire space of irrational numbers.
rate research
Read More
For a metric space $X$, let $mathsf FX$ be the space of all nonempty finite subsets of $X$ endowed with the largest metric $d^1_{mathsf FX}$ such that for every $ninmathbb N$ the map $X^ntomathsf FX$, $(x_1,dots,x_n)mapsto {x_1,dots,x_n}$, is non-expanding with respect to the $ell^1$-metric on $X^n$. We study the completion of the metric space $mathsf F^1!X=(mathsf FX,d^1_{mathsf FX})$ and prove that it coincides with the space $mathsf Z^1!X$ of nonempty compact subsets of $X$ that have zero length (defined with the help of graphs). We prove that each subset of zero length in a metric space has 1-dimensional Hausdorff measure zero. A subset $A$ of the real line has zero length if and only if its closure is compact and has Lebesgue measure zero. On the other hand, for every $nge 2$ the Euclidean space $mathbb R^n$ contains a compact subset of 1-dimensional Hausdorff measure zero that fails to have zero length.
We consider three monads on Top, the category of topological spaces, which formalize topological aspects of probability and possibility in categorical terms. The first one is the Hoare hyperspace monad H, which assigns to every space its space of closed subsets equipped with the lower Vietoris topology. The second is the monad V of continuous valuations, also known as the extended probabilistic powerdomain. We construct both monads in a unified way in terms of double dualization. This reveals a close analogy between them, and allows us to prove that the operation of taking the support of a continuous valuation is a morphism of monads from V to H. In particular, this implies that every H-algebra (topological complete semilattice) is also a V-algebra. Third, we show that V can be restricted to a submonad of tau-smooth probability measures on Top. By composing these two morphisms of monads, we obtain that taking the support of a tau-smooth probability measure is also a morphism of monads.
We introduce and study some generalizations of regular spaces, which were motivated by studying continuity properties of functions between (regular) topological spaces. In particular, we prove that a first-countable Hausdorff topological space is regular if and only if it does not contain a topological copy of the Gutik hedgehog.
A Hausdorff topological group is called minimal if it does not admit a strictly coarser Hausdorff group topology. This paper mostly deals with the topological group $H_+(X)$ of order-preserving homeomorphisms of a compact linearly ordered connected space $X$. We provide a sufficient condition on $X$ under which the topological group $H_+(X)$ is minimal. This condition is satisfied, for example, by: the unit interval, the ordered square, the extended long line and the circle (endowed with its cyclic order). In fact, these groups are even $a$-minimal, meaning, in this setting, that the compact-open topology on $G$ is the smallest Hausdorff group topology on $G$. One of the key ideas is to verify that for such $X$ the Zariski and the Markov topologies on the group $H_+(X)$ coincide with the compact-open topology. The technique in this article is mainly based on a work of Gartside and Glyn.
Classes SSGP(n)(n < omega) of topological groups are defined, and the class-theoretic inclusions SSGP(n) subseteq SSGP(n+1) subseteq m.a.p. are established and shown proper. These classes are investigated with respect to the properties normally studied by topologists (products, quotients, passage to dense subgroups, and the like). In passing the authors establish the presence of the SSGP(1) or SSGP(2) property in many of the early examples in the literature of abelian m.a.p. groups.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
