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991.
Let E be a vector bundle of rank 2 over an algebraic curve X of genus g ≥ 2. In this paper, we prove that E is determined by its maximal line subbundles if it is general. By restudying the results of Lange and Narasimhan which relates
the maximal line subbundles with the secant varieties of X, we observe that the proof can be reduced to proving some cohomological conditions satisfied by the maximal line subbundles.
By noting the similarity between these conditions and the notion of very stable bundles, we get the result for the case when
E has Segre invariant s(E) = g. Also by using the elementary transformation, we have the result for the case s(E) = g−1.
I. Choe and J. Choy were supported by KOSEF (R01-2003-000-11634-0) and S. Park was supported by Korea Research Foundation
Grant funded by Korea Government(MOEHRD, Basic Research Promotion Fund) (KRF-2005-070-C00005) 相似文献
992.
Philippe Carmona Frdrique Petit Marc Yor 《Annales de l'Institut Henri Poincaré (B) Probabilités et Statistiques》2004,40(6):737-758
D. Williams' path decomposition and Pitman's representation theorem for BES(3) are expressions of some deep relations between reflecting Brownian motion and the 3-dimensional Bessel process.In [Ph. Carmona et al., Stochastic Process. Appl. 7 (1999) 323–333], we presented an attempt to relate better reflecting Brownian motion and the 2-dimensional Bessel process, using space and time changes related to the Ray–Knight theorems on local times, in the manner of Jeulin [Lect. Notes Math., vol. 1118, Springer, Berlin, 1985] and Biane–Yor [Bull. Sci. Math. 2ème Sér. 111 (1987) 23–101].Here, we characterize the law of a triplet linked to the perturbed Brownian motion which naturally arises in [Ph. Carmona et al., Stochastic Proc. Appl. 7 (1999) 323–333], and we point out its relations with Bessel processes of several dimensions.The results provide some new understanding of the generalizations of Lévy's arc sine law for perturbed Brownian motions previously obtained by the second author. 相似文献
993.
Peter M. Akhmetiev 《Topology and its Applications》2004,140(2-3):133-149
Let n3 and
be positive integers, f :Sn→Sn be a C0-mapping, and
denote the standard embedding. As an application of the Pontryagin–Thom construction in the special case of the two-point configuration space, we construct complete algebraic obstructions O(f) and
to discrete and isotopic realizability (realizability as an embedding) of the mapping Jf. The obstructions are described in terms of stable (equivariant) homotopy groups of neighborhoods of the singular set Σ(f)={(x,y)Sn×Snf(x)=f(y), x≠y}.
A standard method of solving problems in differential topology is to translate them into homotopy theory by means of bordism theory and Pontryagin–Thom construction. By this method we give a generalization of the van-Kampen–Skopenkov obstruction to discrete realizability of f and the van-Kampen–Melikhov obstruction to isotopic realizability of f. The latter are complete only in the case d=0 and are the images of our obstructions under a Hurewicz homomorphism.
We consider several examples of computation of the obstructions. 相似文献
994.
Harumi Hattori 《Journal of Differential Equations》2004,205(1):229-252
We consider the Riemann problem for a system of conservation laws related to a phase transition problem. The system is nonisentropic and we treat the case where the latent heat is not zero. We study the cases where the initial data are given in the same phase and in the different phases. The role of the entropy condition is studied as well as the kinetic relation and the entropy rate admissibility criterion. We confine our attention to the case where the speeds of phase boundaries are close to zero. This is one interesting case in physics. We discuss the number of phase boundaries consistent with the above criteria and the uniqueness and nonuniqueness issue of the solution to the Riemann problem. 相似文献
995.
This paper classifies (2,1)-stable and (1,2)-stable unfoldings of map germs with codimentions ≤ 3 by means of the algorithm given by Wassermann. 相似文献
996.
A generalization of the Cauchy theory of forces and stresses to the geometry of differentiable manifolds is presented using
the language of differential forms. Body forces and surface forces are defined in terms of the power densities they produce
when acting on generalized velocity fields. The normal to the boundary is replaced by the tangent space equipped with the
outer orientation induced by outward pointing vectors. Assuming that the dimension of the material manifold is m, stresses are modelled as m − 1 covector valued forms. Cauchy's formula is replaced by the restriction of the stress form to the tangent space of the
boundary while the outer orientation of the tangent space is taken into account. The special cases of volume manifolds and
Riemannian manifolds are discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
Sandra Fital 《Journal of Mathematical Analysis and Applications》2006,318(2):648-657
We consider the initial value problem for a nonsymmetric matrix Riccati differential equation, where the four coefficient matrices form an M-matrix. We show that for a wide range of initial values the Riccati differential equation has a global solution X(t) on [0,∞) and X(t) converges to the stable equilibrium solution as t goes to infinity. 相似文献
998.
In this paper we give a theoretical foundation to the asymptotical development proposed by V. P. Maslov for shock type singular solutions of conservations laws, in the framework of Colombeau theory of generalized functions. Indeed, operating with Colombeau differential algebra of simplified generalized functions, we proof that Hugoniot–Maslov chains are necessary conditions for the existence of shock waves in conservation laws with polynomial flows. As a particular case, these equations include the Hugoniot–Maslov chains for shock waves in the Hopf equation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
V. Rosenhaus 《Reports on Mathematical Physics》2003,51(1):71-86
In this paper we study local conservation laws for the equation of short waves in the form of a variational problem. We analyze an infinite symmetry group of the equation and generate a finite number of conservation laws corresponding to given infinite symmetries through appropriate boundary conditions. 相似文献
1000.
Semidefinite programming in combinatorial optimization 总被引:7,自引:0,他引:7
Michel X. Goemans 《Mathematical Programming》1997,79(1-3):143-161
We discuss the use of semidefinite programming for combinatorial optimization problems. The main topics covered include (i)
the Lovász theta function and its applications to stable sets, perfect graphs, and coding theory, (ii) the automatic generation
of strong valid inequalities, (iii) the maximum cut problem and related problems, and (iv) the embedding of finite metric
spaces and its relationship to the sparsest cut problem.
Part of this work is supported by NSF contract 9623859-CCR, a Sloan Foundation Fellowship, and ARPA Contract N00014-95-1-1246. 相似文献