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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Sbornik Mathematicsarrow_drop_down
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Sbornik Mathematics
Article . 2018 . Peer-reviewed
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image/svg+xml Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao Closed Access logo, derived from PLoS Open Access logo. This version with transparent background. http://commons.wikimedia.org/wiki/File:Closed_Access_logo_transparent.svg Jakob Voss, based on art designer at PLoS, modified by Wikipedia users Nina and Beao
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Article . 2018
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On the cardinality of the coincidence set for mappings of metric, normed and partially ordered spaces

Authors: Arutyunov A.V.; Zhukovskiy E.S.; Zhukovskiy S.E.;

On the cardinality of the coincidence set for mappings of metric, normed and partially ordered spaces

Abstract

For two set-valued mappings \(\Phi,\Psi: X\multimap Y\) the coincidence set is defined as \(\text{Coin}(\Phi,\Psi):=\{\xi\in X \mid \Phi(\xi)\cap\Psi(\xi)\not=\emptyset\}\). Let \(\alpha>0\) and \(\beta\geq0\). A map \(\Psi:X\multimap Y\) between metric spaces is called an \(\alpha\)-covering if \(B_Y(\Psi(x_0);\alpha r)\subset \Psi(B_X(x_0;r))\) for all \(x_0\in X\) and \(r>0\) where of course, \(B_X\) and \(B_Y\) denote the corresponding closed balls. \(\Psi\) is called \(\beta\)-Lipschitz if \(h_Y(\Phi(x),\Phi(u))\leq\beta\rho_X(x,u)\) for all \(x,u\in X\) where \(h_Y\) denotes the Hausdorff-distance in \(Y\) and \(\rho_X\) the metric in \(X\). Let now be \(\Omega\) be an arbitrary set (finite or infinite) and let \(\Phi:X\multimap Y\) be a closed \(\alpha\)-covering and let \(\Psi:X\multimap Y\) be closed and \(\beta\)-Lipschitz. Assume that \(\alpha>\beta\) and that at least one of \(\Phi\) and \(\Psi\) has a graph which is a complete metric space. The authors use the following rather technical assumption: There is an injective mapping \(\Omega\to X\), \(j\mapsto x_j\), and for each \(j\in\Omega\) there is an \(\epsilon_j>0\) such that for \(i\not=j\) we have that \(\rho(x_i,x_j)\geq\frac{\text{dist}_Y(\Psi(x_i),\Phi(x_i))+\text{dist}_Y(\Psi(x_j),\Phi(x_j))}{\alpha-\beta}+\epsilon_i+\epsilon_j\). Let then \((y_j)_{j\in\Omega}\) be a family in \(Y\) such that \(y_j\in\Psi(x_j)\). Then there exist families \((\xi_j)_{j\in\Omega}\) in \(X\) and \((\eta_j)_{j\in\Omega}\) in \(Y\) such that \((\xi_j,\eta_j)\) belongs to the intersection of the graphs of \(\Phi\) and \(\Psi\), \(\xi_i\not=\xi_j\) for \(i\not=j\), and the cardinality of \(\text{Coinc}(\Psi,\Phi)\) is not smaller than the cardinality of \(\Omega\). There are several results in the same spirit where special consideration is given to the case of normed spaces.

Country
Russian Federation
Related Organizations
Keywords

coincidence point, covering mapping, Fixed-point and coincidence theorems (topological aspects), Covering mapping, Coincidence point, 510, Set-valued maps in general topology

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
7
Top 10%
Average
Average
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