Results 31 to 40 of about 605 (180)
On modulus of noncompact convexity for a strictly minimalizable measure of noncompactness
Gulf Journal of Mathematics, 2014 In this paper we consider modulus of noncompact convexity ΔX,φ associated with the strictly minimalizable measure of noncompactness φ. We also give some its properties and show its continuity on the interval [0, φ(BX)).
Rekic-Vukovic, Amra +2 more
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Some remarks on measures of noncompactness and retractions onto spheres [PDF]
, 2007 Some ways to obtain upper and lower bounds for measures of noncompactness of retractions onto spheres in infinite-dimensional normed spaces are discussed. Moreover, relations with 0-epi maps are revealed and the extension of condensing maps on spheres is
Kim, In-Sook, Väth, Martin
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Remarks on Various Measures of Noncompactness
Journal of Mathematical Analysis and Applications, 1993 Let \(\Omega\) be a bounded set in a metric space \(M\). Denote \(\alpha(\Omega)=\inf\{d>0:\Omega\text{ can be covered by a finite number of sets of diameter at most }d\},\) \(\beta(\Omega)=\inf\{d>0:\Omega\text{ has a finite } d\text{-net in }M\},\) \(\delta(\Omega)=\sup\{\alpha(\Omega'):\Omega'\subseteq\Omega\text{ and } \Omega'\text{ is an } \alpha ...
openaire +2 more sources
A Coarse Geometric Approach to Graph Layout Problems
Journal of Graph Theory, EarlyView.ABSTRACT We define a range of new coarse geometric invariants based on various graph–theoretic measures of complexity for finite graphs, including treewidth, pathwidth, cutwidth and bandwidth. We prove that, for bounded degree graphs, these invariants can be used to define functions which satisfy a strong monotonicity property, namely, they are ...
Wanying Huang +3 more
wiley +1 more source
Weak Solutions for Nonlinear Fractional Differential Equations in Banach Spaces
Discrete Dynamics in Nature and Society, 2012 We discuss the existence of weak solutions for a nonlinear boundary value problem of fractional differential equations in Banach space. Our analysis relies on the Mönch's fixed point theorem combined with the technique of measures of weak noncompactness.
Wen-Xue Zhou +2 more
doaj +1 more source
On the Existence of Solutions of Dynamic Equations on Time Scales in Banach Spaces
Mathematical Methods in the Applied Sciences, EarlyView.ABSTRACT In this paper we address the question of solvability of dynamic equations on time scales in Banach spaces. In particular, our main theorem extends the result for classical differential equations in Banach spaces of Banaś and Goebel established in [5], to an arbitrary time scale.
Dušan Oberta
wiley +1 more source
On the bounded compact approximation property and measures of noncompactness [PDF]
, 1987 The Banach spaces with the bounded compact approximation property are characterized by the completeness of measures of noncompactness. Applications to the theory of semi-Fredholm operators and to the algebraic properties of their canonical images in the ...
Astala, Kari, Tylli, Hans-Olav
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Surface subgroups for cocompact lattices of isometries of H2n$\mathbb {H}^{2n}$
Journal of Topology, Volume 19, Issue 3, September 2026.Abstract We prove the existence of surface subgroups within any cocompact lattice Γ$\Gamma$ in SO(2n,1)$\mathrm{SO}(2n,1)$ for n⩾2$n\geqslant 2$. This result addresses the cases missing from the work of Hamenstädt in 2015, who constructed surface subgroups in cocompact lattices for all other rank‐1 simple Lie groups of noncompact type.
Jeremy Kahn, Zhenghao Rao
wiley +1 more source
Geometrical Coefficients and Measures of Noncompactness [PDF]
, 1992 This thesis studies various measures of noncompactness and some geometrical coefficients in metric or Bauach spaces. These geometrical numbers are useful in the study of measures of noncompactness, some of which are interesting quantities in fixed point ...
Zhao, Weiyu
core
Measures of noncompactness and upper semi-Fredholm perturbation theorems [PDF]
, 1993 We introduce the concept of a perturbation function, which allows us to give a general approach to the question of obtaining perturbation theorems for upper semi-Fredholm operators.
Fernando Galaz-Fontes
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