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901.
Armengol Gasull 《Journal of Differential Equations》2005,213(2):255-288
The generic isolated bifurcations for one-parameter families of smooth planar vector fields {Xμ} which give rise to periodic orbits are: the Andronov-Hopf bifurcation, the bifurcation from a semi-stable periodic orbit, the saddle-node loop bifurcation and the saddle loop bifurcation. In this paper we obtain the dominant term of the asymptotic behaviour of the period of the limit cycles appearing in each of these bifurcations in terms of μ when we are near the bifurcation. The method used to study the first two bifurcations is also used to solve the same problem in another two situations: a generalization of the Andronov-Hopf bifurcation to vector fields starting with a special monodromic jet; and the Hopf bifurcation at infinity for families of polynomial vector fields. 相似文献
902.
A nonparametric statistical model of small diffusion type is compared with its discretization by a stochastic Euler difference
scheme. It is shown that the discrete and continuous models are asymptotically equivalent in the sense of Le Cam's deficiency
distance for statistical experiments, when the discretization step decreases with the noise intensity ε.
Received: 12 April 1996 / Revised version: 29 October 1997 相似文献
903.
904.
Ferenc Móricz 《Archiv der Mathematik》2006,86(4):375-384
In recent years, the almost sure central limit theorem attracted widespread attention in Probability Theory. It involves the
harmonic (also called logarithmic) averages of a certain numerical sequence formed from a sequence of independent, identically
distributed random variables. Our primary aim is to study the convergence behavior of the sequence of harmonic averages of
a given numerical sequence from the viewpoint of Summability Theory.
Received: 12 May 2005; revised: 1 July 2005 相似文献
905.
本文定义了一个由范畴 RMRl到范畴A Grn0 的函子G,并证明了函子G保持分量正合及全正合,关于范畴AGGrn0 证明了定理: 相似文献
906.
Summary. Motivated by a hedging problem in mathematical finance, El Karoui and Quenez [7] and Kramkov [14] have developed optional
versions of the Doob-Meyer decomposition which hold simultaneously for all equivalent martingale measures. We investigate
the general structure of such optional decompositions, both in additive and in multiplicative form, and under constraints
corresponding to different classes of equivalent measures. As an application, we extend results of Karatzas and Cvitanić [3]
on hedging problems with constrained portfolios.
Received: 6 August 1996/In revised form: 5 March 1997 相似文献
907.
Marco Grandis 《Applied Categorical Structures》1994,2(4):351-406
We develop here a version of abstract homotopical algebra based onhomotopy kernels andcokernels, which are particular homotopy limits and colimits. These notions are introduced in anh-category, a sort of two-dimensional context more general than a 2-category, abstracting thenearly 2-categorical properties of topological spaces, continuous maps and homotopies. A setting which applies also, at different extents, to cubical or simplicial sets, chain complexes, chain algebras, ... and in which homotopical algebra can be established as a two-dimensional enrichment of homological algebra.Actually, a hierarchy of notions ofh-,h1-, ...h4-categories is introduced, through progressive enrichment of thevertical structure of homotopies, so that the strongest notion,h4-category, is a sort of relaxed 2-category. After investigating homotopy pullbacks and homotopical diagrammatical lemmas in these settings, we introduceright semihomotopical categories, ash-categories provided with terminal object and homotopy cokernels (mapping cones), andright homotopical categories, provided also with anh4-structure and verifying second-order regularity properties forh-cokernels.In these frames we study the Puppe sequence of a map, its comparison with the sequence of iterated homotopy cokernels and theh-cogroup structure of the suspension endofunctor. Left (semi-) homotopical categories, based on homotopy kernels, give the fibration sequence of a map and theh-group of loops. Finally, the self-dual notion of homotopical categories is considered, together with their stability properties.Lavoro esequito nell'ambito dei progetti di ricerca del MURST. 相似文献
908.
Key pathways of interaction between growing radicals of vinyl monomers and bis(cyclopentadienyl) derivatives of Group IV–VI
transition metal dichlorides were studied by the BP86/6-31G(d) and B3LYP/LanL2DZ quantum chemical methods. Prospects for use
of these organometallic compounds as chain growth regulators in controlled polymerization were assessed. The character of
the interaction of the compounds studied with the growing radicals is mainly determined by the metal atom.
Dedicated to Academician G. A. Abakumov on the occasion of his 70th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1690–1694, September, 2007. 相似文献
909.
回顾了域上典型群的生成问题所得成果,对局部环上典型群生成问题的研究,作了一个展示,并按展示的范式,给出了辛群生成定理的证明. 相似文献
910.
An algebra A over a field k is FCR if every finite dimensional representation of A is completely reducible and the intersection of the kernels of these representations is zero. We give a useful characterization
of FCR-algebras and apply this to C
*-algebras and to localizations. Moreover, we show that “small” products and sums of FCR-algebras are again FCR.
Received: 25 October 2000 相似文献