66,927 research outputs found
Equivariant wave maps exterior to a ball
We consider the exterior Cauchy-Dirichlet problem for equivariant wave maps
from 3+1 dimensional Minkowski spacetime into the three-sphere. Using mixed
analytical and numerical methods we show that, for a given topological degree
of the map, all solutions starting from smooth finite energy initial data
converge to the unique static solution (harmonic map). The asymptotics of this
relaxation process is described in detail. We hope that our model will provide
an attractive mathematical setting for gaining insight into
dissipation-by-dispersion phenomena, in particular the soliton resolution
conjecture.Comment: 16 pages, 9 figure
Mixed quasi-\'etale surfaces, new surfaces of general type with and their fundamental group
We call a projective surface mixed quasi-\'etale quotient if there exists
a curve of genus and a finite group that acts on exchanging the factors such that and the map has finite branch locus. The minimal resolution of its
singularities is called mixed quasi-\'etale surface. We study the mixed
quasi-\'etale surfaces under the assumption that has only
nodes as singularities, where is the index two subgroup of
the elements that do not exchange the factors. We classify the minimal regular
surfaces with whose canonical model is a mixed quasi-\'etale quotient
as above. All these surfaces are of general type and as an important byproduct,
we provide an example of a numerical Campedelli surface with topological
fundamental group \bbZ_4, and we realize 2 new topological types of surfaces
of general type. Three of the families we construct are \bbQ-homology
projective planes.Comment: 18 pages, 3 tables, v2: change title, exposition improved; v3: minor
corrections, final version to be published in Collectanea Mathematic
A Comment on Quantum Distribution Functions and the OSV Conjecture
Using the attractor mechanism and the relation between the quantization of
and topological strings on a Calabi Yau threefold we define a
map from BPS black holes into coherent states. This map allows us to represent
the Bekenstein-Hawking-Wald entropy as a quantum distribution function on the
phase space . This distribution function is a mixed
Husimi/anti-Husimi distribution corresponding to the different normal ordering
prescriptions for the string coupling and deviations of the complex structure
moduli. From the integral representation of this distribution function in terms
of the Wigner distribution we recover the Ooguri-Strominger-Vafa (OSV)
conjecture in the region "at infinity" of the complex structure moduli space.
The physical meaning of the OSV corrections are briefly discussed in this
limit.Comment: 27 pages. v2:reference and footnote adde
Y -cone metric spaces and coupled common fixed point results with application to integral equation
This paper acquaints with a concept of Y -cone metric space and to study some topological properties of Y -cone metric space. We prove the coupled common fixed point results for mixed weakly monotone map in ordered Y -cone metric spaces. We give an example, which constitutes the main theorem.Publisher's Versio
Shrinkers, expanders, and the unique continuation beyond generic blowup in the heat flow for harmonic maps between spheres
Using mixed analytical and numerical methods we investigate the development
of singularities in the heat flow for corotational harmonic maps from the
-dimensional sphere to itself for . By gluing together
shrinking and expanding asymptotically self-similar solutions we construct
global weak solutions which are smooth everywhere except for a sequence of
times at which there occurs the type I blow-up at one
of the poles of the sphere. We show that in the generic case the continuation
beyond blow-up is unique, the topological degree of the map changes by one at
each blow-up time , and eventually the solution comes to rest at the zero
energy constant map.Comment: 24 pages, 8 figures, minor corrections, matches published versio
Absolute neighbourhood retracts and spaces of holomorphic maps from Stein manifolds to Oka manifolds
The basic result of Oka theory, due to Gromov, states that every continuous
map from a Stein manifold to an elliptic manifold can be deformed
to a holomorphic map. It is natural to ask whether this can be done for all
at once, in a way that depends continuously on and leaves fixed if it
is holomorphic to begin with. In other words, is \scrO(S,X) a deformation
retract of \scrC(S,X)? We prove that it is if has a strictly
plurisubharmonic Morse exhaustion with finitely many critical points; in
particular, if is affine algebraic. The only property of used in the
proof is the parametric Oka property with approximation with respect to finite
polyhedra, so our theorem holds under the weaker assumption that is an Oka
manifold. Our main tool, apart from Oka theory itself, is the theory of
absolute neighbourhood retracts. We also make use of the mixed model structure
on the category of topological spaces.Comment: Version 2: A few very minor improvements to the exposition. Version
3: Another few very minor improvements to the exposition. To appear in
Proceedings AM
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