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Stability Of Spherically Symmetric Wave Maps
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Book Synopsis Stability of Spherically Symmetric Wave Maps by : Joachim Krieger
Download or read book Stability of Spherically Symmetric Wave Maps written by Joachim Krieger and published by American Mathematical Soc.. This book was released on 2006 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents a study of Wave Maps from ${\mathbf{R}}^{2+1}$ to the hyperbolic plane ${\mathbf{H}}^{2}$ with smooth compactly supported initial data which are close to smooth spherically symmetric initial data with respect to some $H^{1+\mu}$, $\mu>0$.
Book Synopsis Developments of Harmonic Maps, Wave Maps and Yang-Mills Fields into Biharmonic Maps, Biwave Maps and Bi-Yang-Mills Fields by : Yuan-Jen Chiang
Download or read book Developments of Harmonic Maps, Wave Maps and Yang-Mills Fields into Biharmonic Maps, Biwave Maps and Bi-Yang-Mills Fields written by Yuan-Jen Chiang and published by Springer Science & Business Media. This book was released on 2013-06-18 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: Harmonic maps between Riemannian manifolds were first established by James Eells and Joseph H. Sampson in 1964. Wave maps are harmonic maps on Minkowski spaces and have been studied since the 1990s. Yang-Mills fields, the critical points of Yang-Mills functionals of connections whose curvature tensors are harmonic, were explored by a few physicists in the 1950s, and biharmonic maps (generalizing harmonic maps) were introduced by Guoying Jiang in 1986. The book presents an overview of the important developments made in these fields since they first came up. Furthermore, it introduces biwave maps (generalizing wave maps) which were first studied by the author in 2009, and bi-Yang-Mills fields (generalizing Yang-Mills fields) first investigated by Toshiyuki Ichiyama, Jun-Ichi Inoguchi and Hajime Urakawa in 2008. Other topics discussed are exponential harmonic maps, exponential wave maps and exponential Yang-Mills fields.
Book Synopsis Gravitation and Astrophysics by : James M. Nester
Download or read book Gravitation and Astrophysics written by James M. Nester and published by World Scientific. This book was released on 2007 with total page 433 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ICGA series of conferences is specially aimed to serve the needs of the workers in this research area in the Asia-Pacific region. The previous conferences of this series have attracted a growing number of local, regional and international participants. 2005 was an auspicious year. Not only was it the International Year of Physics, commemorating Einstein''s great achievements of 1905, it also was the anniversary of Einstein''s development of General Relativity: he submitted the final form of his field equations on 25 November, 1915. Nine decades years later, around 40 Taiwan-based participants were joined by over 40 distinguished visitors from Canada, China, France, Japan, Korea, Russia, and the USA, and this volume includes many of the papers that were presented. The depth and breadth of these contributions reflect the high quality of the meeting and the development of the field in the Asia-Pacific region. Sample Chapter(s). Chapter 1: Progress in Testing Newtonian Inverse Square Law (234 KB). Contents: Experimental Tests of Gravity; Numerical Relativity; Cosmology; Astrophysics; Quantum Gravity; Classical Gravity. Readership: Graduate students and researchers in astrophysics, gravitation, cosmology and theoretical physics.
Book Synopsis Invariant Differential Operators for Quantum Symmetric Spaces by : Gail Letzter
Download or read book Invariant Differential Operators for Quantum Symmetric Spaces written by Gail Letzter and published by American Mathematical Soc.. This book was released on 2008 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper studies quantum invariant differential operators for quantum symmetric spaces in the maximally split case. The main results are quantum versions of theorems of Harish-Chandra and Helgason: There is a Harish-Chandra map which induces an isomorphism between the ring of quantum invariant differential operators and the ring of invariants of a certain Laurent polynomial ring under an action of the restricted Weyl group. Moreover, the image of the center under this map is the entire invariant ring if and only if the underlying irreducible symmetric pair is not of four exceptional types. In the process, the author finds a particularly nice basis for the quantum invariant differential operators that provides a new interpretation of difference operators associated to Macdonald polynomials.
Book Synopsis The Generalized Triangle Inequalities in Symmetric Spaces and Buildings with Applications to Algebra by : Michael Kapovich
Download or read book The Generalized Triangle Inequalities in Symmetric Spaces and Buildings with Applications to Algebra written by Michael Kapovich and published by American Mathematical Soc.. This book was released on 2008 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper the authors apply their results on the geometry of polygons in infinitesimal symmetric spaces and symmetric spaces and buildings to four problems in algebraic group theory. Two of these problems are generalizations of the problems of finding the constraints on the eigenvalues (resp. singular values) of a sum (resp. product) when the eigenvalues (singular values) of each summand (factor) are fixed. The other two problems are related to the nonvanishing of the structure constants of the (spherical) Hecke and representation rings associated with a split reductive algebraic group over $\mathbb{Q}$ and its complex Langlands' dual. The authors give a new proof of the Saturation Conjecture for $GL(\ell)$ as a consequence of their solution of the corresponding saturation problem for the Hecke structure constants for all split reductive algebraic groups over $\mathbb{Q}$.
Book Synopsis Symmetric and Alternating Groups as Monodromy Groups of Riemann Surfaces I by : Robert M. Guralnick
Download or read book Symmetric and Alternating Groups as Monodromy Groups of Riemann Surfaces I written by Robert M. Guralnick and published by American Mathematical Soc.. This book was released on 2007 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors consider indecomposable degree $n$ covers of Riemann surfaces with monodromy group an alternating or symmetric group of degree $d$. They show that if the cover has five or more branch points then the genus grows rapidly with $n$ unless either $d = n$ or the curves have genus zero, there are precisely five branch points and $n =d(d-1)/2$. Similarly, if there is a totally ramified point, then without restriction on the number of branch points the genus grows rapidly with $n$ unless either $d=n$ or the curves have genus zero and $n=d(d-1)/2$. One consequence of these results is that if $f:X \rightarrow \mathbb{P 1$ is indecomposable of degree $n$ with $X$ the generic Riemann surface of genus $g \ge 4$, then the monodromy group is $S n$ or $A n$ (and both can occur for $n$ sufficiently large). The authors also show if that if $f(x)$ is an indecomposable rational function of degree $n$ branched at $9$ or more points, then its monodromy group is $A n$ or $S n$.Finally, they answer a question of Elkies by showing that the curve parameterizing extensions of a number field given by an irreducible trinomial with Galois group $H$ has large genus unless $H=A n$ or $S n$ or $n$ is very small.
Book Synopsis Borel Liftings of Borel Sets: Some Decidable and Undecidable Statements by : Gabriel Debs
Download or read book Borel Liftings of Borel Sets: Some Decidable and Undecidable Statements written by Gabriel Debs and published by American Mathematical Soc.. This book was released on 2007 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the aims of this work is to investigate some natural properties of Borel sets which are undecidable in $ZFC$. The authors' starting point is the following elementary, though non-trivial result: Consider $X \subset 2omega\times2omega$, set $Y=\pi(X)$, where $\pi$ denotes the canonical projection of $2omega\times2omega$ onto the first factor, and suppose that $(\star)$: Any compact subset of $Y$ is the projection of some compact subset of $X$. If moreover $X$ is $\mathbf{\Pi 0 2$ then $(\star\star)$: The restriction of $\pi$ to some relatively closed subset of $X$ is perfect onto $Y$ it follows that in the present case $Y$ is also $\mathbf{\Pi 0 2$. Notice that the reverse implication $(\star\star)\Rightarrow(\star)$ holds trivially for any $X$ and $Y$. But the implication $(\star)\Rightarrow (\star\star)$ for an arbitrary Borel set $X \subset 2omega\times2omega$ is equivalent to the statement $\forall \alpha\in \omegaomega, \, \aleph 1$ is inaccessible in $L(\alpha)$. More precisely The authors prove that the validity of $(\star)\Rightarrow(\star\star)$ for all $X \in \varSigma0 {1+\xi+1 $, is equivalent to $\aleph \xi \aleph 1$. $ZFC$, derive from $(\star)$ the weaker conclusion that $Y$ is also Borel and of the same Baire class as $X$. This last result solves an old problem about compact covering mappings. In fact these results are closely related to the following general boundedness principle Lift$(X, Y)$: If any compact subset of $Y$ admits a continuous lifting in $X$, then $Y$ admits a continuous lifting in $X$, where by a lifting of $Z\subset \pi(X)$ in $X$ we mean a mapping on $Z$ whose graph is contained in $X$. The main result of this work will give the exact set theoretical strength of this principle depending on the descriptive complexity of $X$ and $Y$. The authors also prove a similar result for a variation of Lift$(X, Y)$ in which continuous liftings are replaced by Borel liftings, and which answers a question of H. Friedman. Among other applications the authors obtain a complete solution to a problem which goes back to Lusin concerning the existence of $\mathbf{\Pi 1 1$ sets with all constituents in some given class $\mathbf{\Gamma $ of Borel sets, improving earlier results by J. Stern and R. Sami. Borel sets (in $ZFC$) of a new type, involving a large amount of abstract algebra. This representation was initially developed for the purposes of this proof, but has several other applications.
Book Synopsis Complicial Sets Characterising the Simplicial Nerves of Strict $\omega $-Categories by : Dominic Verity
Download or read book Complicial Sets Characterising the Simplicial Nerves of Strict $\omega $-Categories written by Dominic Verity and published by American Mathematical Soc.. This book was released on 2008 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: The primary purpose of this work is to characterise strict $\omega$-categories as simplicial sets with structure. The author proves the Street-Roberts conjecture in the form formulated by Ross Street in his work on Orientals, which states that they are exactly the ``complicial sets'' defined and named by John Roberts in his handwritten notes of that title (circa 1978). On the way the author substantially develops Roberts' theory of complicial sets itself and makes contributions to Street's theory of parity complexes. In particular, he studies a new monoidal closed structure on the category of complicial sets which he shows to be the appropriate generalisation of the (lax) Gray tensor product of 2-categories to this context. Under Street's $\omega$-categorical nerve construction, which the author shows to be an equivalence, this tensor product coincides with those of Steiner, Crans and others.
Book Synopsis Tangential Boundary Stabilization of Navier-Stokes Equations by : Viorel Barbu
Download or read book Tangential Boundary Stabilization of Navier-Stokes Equations written by Viorel Barbu and published by American Mathematical Soc.. This book was released on 2006 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to inject dissipation as to force local exponential stabilization of the steady-state solutions, an Optimal Control Problem (OCP) with a quadratic cost functional over an infinite time-horizon is introduced for the linearized N-S equations. As a result, the same Riccati-based, optimal boundary feedback controller which is obtained in the linearized OCP is then selected and implemented also on the full N-S system. For $d=3$, the OCP falls definitely outside the boundaries of established optimal control theory for parabolic systems with boundary controls, in that the combined index of unboundedness--between the unboundedness of the boundary control operator and the unboundedness of the penalization or observation operator--is strictly larger than $\tfrac{3}{2}$, as expressed in terms of fractional powers of the free-dynamics operator. In contrast, established (and rich) optimal control theory [L-T.2] of boundary control parabolic problems and corresponding algebraic Riccati theory requires a combined index of unboundedness strictly less than 1. An additional preliminary serious difficulty to overcome lies at the outset of the program, in establishing that the present highly non-standard OCP--with the aforementioned high level of unboundedness in control and observation operators and subject, moreover, to the additional constraint that the controllers be pointwise tangential--be non-empty; that is, it satisfies the so-called Finite Cost Condition [L-T.2].
Book Synopsis The Universal Kobayashi-Hitchin Correspondence on Hermitian Manifolds by : Martin Lübke
Download or read book The Universal Kobayashi-Hitchin Correspondence on Hermitian Manifolds written by Martin Lübke and published by American Mathematical Soc.. This book was released on 2006 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: We prove a very general Kobayashi-Hitchin correspondence on arbitrary compact Hermitian manifolds, and we discuss differential geometric properties of the corresponding moduli spaces. This correspondence refers to moduli spaces of ``universal holomorphic oriented pairs''. Most of the classical moduli problems in complex geometry (e. g. holomorphic bundles with reductive structure groups, holomorphic pairs, holomorphic Higgs pairs, Witten triples, arbitrary quiver moduli problems) are special cases of this universal classification problem. Our Kobayashi-Hitchin correspondence relates the complex geometric concept ``polystable oriented holomorphic pair'' to the existence of a reduction solving a generalized Hermitian-Einstein equation. The proof is based on the Uhlenbeck-Yau continuity method. Using ideas from Donaldson theory, we further introduce and investigate canonical Hermitian metrics on such moduli spaces. We discuss in detail remarkable classes of moduli spaces in the non-Kahlerian framework: Oriented holomorphic structures, Quot-spaces, oriented holomorphic pairs and oriented vortices, non-abelian Seiberg-Witten monopoles.
Book Synopsis Semisolvability of Semisimple Hopf Algebras of Low Dimension by : Sonia Natale
Download or read book Semisolvability of Semisimple Hopf Algebras of Low Dimension written by Sonia Natale and published by American Mathematical Soc.. This book was released on 2007 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: The author proves that every semisimple Hopf algebra of dimension less than $60$ over an algebraically closed field $k$ of characteristic zero is either upper or lower semisolvable up to a cocycle twist.
Book Synopsis Weil-Petersson Metric on the Universal Teichmuller Space by : Leon Armenovich Takhtadzhi︠a︡n
Download or read book Weil-Petersson Metric on the Universal Teichmuller Space written by Leon Armenovich Takhtadzhi︠a︡n and published by American Mathematical Soc.. This book was released on 2006 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this memoir, we prove that the universal Teichmuller space $T(1)$ carries a new structure of a complex Hilbert manifold and show that the connected component of the identity of $T(1)$ -- the Hilbert submanifold $T {0 (1)$ -- is a topological group. We define a Weil-Petersson metric on $T(1)$ by Hilbert space inner products on tangent spaces, compute its Riemann curvature tensor, and show that $T(1)$ is a Kahler-Einstein manifold with negative Ricci and sectional curvatures. We introduce and compute Mumford-Miller-Morita characteristic forms for the vertical tangent bundle of the universal Teichmuller curve fibration over the universal Teichmuller space. As an application, we derive Wolpert curvature formulas for the finite-dimensional Teichmuller spaces from the formulas for the universal Teichmuller space. We study in detail the Hilbert manifold structure on $T {0 (1)$ and characterize points on $T {0 (1)$ in terms of Bers and pre-Bers embeddings by proving that the Grunsky operators $B {1 $ and The results of this memoir were presented in our e-prints: Weil-Petersson metric on the universal Teichmuller space I. Curvature properties and Chern forms, arXiv:math.CV/0312172 (2003), and Weil-Petersson metric on the universal Teichmuller space II. Kahler potential and period mapping, arXiv:math.CV/0406408 (2004).
Book Synopsis Carleson Measures and Interpolating Sequences for Besov Spaces on Complex Balls by : Nicola Arcozzi
Download or read book Carleson Measures and Interpolating Sequences for Besov Spaces on Complex Balls written by Nicola Arcozzi and published by American Mathematical Soc.. This book was released on 2006 with total page 163 pages. Available in PDF, EPUB and Kindle. Book excerpt: We characterize Carleson measures for the analytic Besov spaces $B_{p}$ on the unit ball $\mathbb{B}_{n}$ in $\mathbb{C}^{n}$ in terms of a discrete tree condition on the associated Bergman tree $\mathcal{T}_{n}$. We also characterize the pointwise multipliers on $B_{p}$ in terms of Carleson measures. We then apply these results to characterize the interpolating sequences in $\mathbb{B}_{n}$ for $B_{p}$ and their multiplier spaces $M_{B_{p}}$, generalizing a theorem of Boe in one dimension.The interpolating sequences for $B_{p}$ and for $M_{B_{p}}$ are precisely those sequences satisfying a separation condition and a Carleson embedding condition. These results hold for $1\less p \less \infty$ with the exceptions that for $2+\frac{1}{n-1}\leq p
Book Synopsis Entropy and Multivariable Interpolation by : Gelu Popescu
Download or read book Entropy and Multivariable Interpolation written by Gelu Popescu and published by American Mathematical Soc.. This book was released on 2006 with total page 83 pages. Available in PDF, EPUB and Kindle. Book excerpt: We define a new notion of entropy for operators on Fock spaces and positive multi-Toeplitz kernels on free semigroups. This is studied in connection with factorization theorems for (e.g., multi-Toeplitz, multi-analytic, etc.) operators on Fock spaces. These results lead to entropy inequalities and entropy formulas for positive multi-Toeplitz kernels on free semigroups (resp. multi-analytic operators) and consequences concerning the extreme points of the unit ball of the noncommutative analytic Toeplitz algebra $F_n^\infty$.We obtain several geometric characterizations of the central intertwining lifting, a maximal principle, and a permanence principle for the noncommutative commutant lifting theorem. Under certain natural conditions, we find explicit forms for the maximal entropy solution of this multivariable commutant lifting theorem. All these results are used to solve maximal entropy interpolation problems in several variables. We obtain explicit forms for the maximal entropy solution (as well as its entropy) of the Sarason, Caratheodory-Schur, and Nevanlinna-Pick type interpolation problems for the noncommutative (resp. commutative) analytic Toeplitz algebra $F_n^\infty$ (resp. $W_n^\infty$) and their tensor products with $B({\mathcal H}, {\mathcal K})$. In particular, we provide explicit forms for the maximal entropy solutions of several interpolation problems on the unit ball of $\mathbb{C}^n$.
Book Synopsis Distribution Solutions of Nonlinear Systems of Conservation Laws by : Michael Sever
Download or read book Distribution Solutions of Nonlinear Systems of Conservation Laws written by Michael Sever and published by American Mathematical Soc.. This book was released on 2007 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: The local structure of solutions of initial value problems for nonlinear systems of conservation laws is considered. Given large initial data, there exist systems with reasonable structural properties for which standard entropy weak solutions cannot be continued after finite time, but for which weaker solutions, valued as measures at a given time, exist. At any given time, the singularities thus arising admit representation as weak limits of suitable approximate solutions in the space of measures with respect to the space variable. Two distinct classes of singularities have emerged in this context, known as delta-shocks and singular shocks. Notwithstanding the similar form of the singularities, the analysis of delta-shocks is very different from that of singular shocks, as are the systems for which they occur. Roughly speaking, the difference is that for delta-shocks, the density approximations majorize the flux approximations, whereas for singular shocks, the flux approximations blow up faster. As against that admissible singular shocks have viscous structure.
Book Synopsis Homological and Homotopical Aspects of Torsion Theories by : Apostolos Beligiannis
Download or read book Homological and Homotopical Aspects of Torsion Theories written by Apostolos Beligiannis and published by American Mathematical Soc.. This book was released on 2007 with total page 207 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this paper the authors investigate homological and homotopical aspects of a concept of torsion which is general enough to cover torsion and cotorsion pairs in abelian categories, $t$-structures and recollements in triangulated categories, and torsion pairs in stable categories. The proper conceptual framework for this study is the general setting of pretriangulated categories, an omnipresent class of additive categories which includes abelian, triangulated, stable, and more generally (homotopy categories of) closed model categories in the sense of Quillen, as special cases. The main focus of their study is on the investigation of the strong connections and the interplay between (co)torsion pairs and tilting theory in abelian, triangulated and stable categories on one hand, and universal cohomology theories induced by torsion pairs on the other hand. These new universal cohomology theories provide a natural generalization of the Tate-Vogel (co)homology theory. The authors also study the connections between torsion theories and closed model structures, which allow them to classify all cotorsion pairs in an abelian category and all torsion pairs in a stable category, in homotopical terms. For instance they obtain a classification of (co)tilting modules along these lines. Finally they give torsion theoretic applications to the structure of Gorenstein and Cohen-Macaulay categories, which provide a natural generalization of Gorenstein and Cohen-Macaulay rings.
Book Synopsis Torus Fibrations, Gerbes, and Duality by : Ron Donagi
Download or read book Torus Fibrations, Gerbes, and Duality written by Ron Donagi and published by American Mathematical Soc.. This book was released on 2008 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Let $X$ be a smooth elliptic fibration over a smooth base $B$. Under mild assumptions, the authors establish a Fourier-Mukai equivalence between the derived categories of two objects, each of which is an $\mathcal{O} DEGREES{\times}$ gerbe over a genus one fibration which is a twisted form
