A CLASS OF FDE WITH DEVIATING ARGUMENT WHICH DEPENDS ON STATE AND RATE OF CHANGE OF THE STATE

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USE OF LIE SYMMETRIES AND THE PAINLEVÉ ANALYSIS IN COSMOLOGY

Abstract

Two techniques for the analysis of differential equations, the Lie method of extended groups and the Painlevé analysis, are reviewed. The implications for integrability in the case of the existence of symmetries in the former or the possession of the Painlevé property in the latter are explored. By way of an example an equation which arises in shear-free flow of a spherically symmetric perfect fluid with conformal symmetry in general relativity is given an extensive treatment with both techniques.     

HOMOLOGICAL PROPERTIES OF TORSION CLASSES UNDER CHANGE OF RINGS

ＨＯＭＯＬＯＧＩＣＡＬ ＰＲＯＰＥＲＴＩＥＳ ＯＦ ＴＯＲＳＩＯＮ ＣＬＡＳＳＥＳ ＵＮＤＥＲ ＣＨＡＮＧＥ ＯＦ ＲＩＮＧＳ ￥ＹＡＯＭＵＳＨＥＮＧＡｂｓｔｒａｃｔ：ＬｅｔＲｂｅａｒｉｎｇｗｉｔｈｉｄｅｎｔｉｔｙ，ｘｂｅａｃｅｎｔｒａｌｅｌｅｍｅｎ...     

ON NECESSARY AND SUFFICIENT CONDITIONS FOR THE EXISTENCE OF CARATHÉODORY SOLUTIONS OF ORDINARY DIFFERENTIAL EQUATIONS

Given two one-sided Markov chains, the authors illustrate a procedure for ascertaining whether they are essentially the same. Precisely, they show how one can determine whether they are block-isomorphic. An application to hydrology is investigated with an example.     

NONLINEAR HOMOTOPY AND PRE-POINCARÉ LEMMAS

Abstract

Most homotopies considered in the literature are linear homotopies of the form h ⁱ (λ) = λx ⁱ + (1—λ)y ⁱ , 0 ≤ λ ≤ 1. Although these prove to be adequate in most instances, they lack direct geometric significance because {h ⁱ (λ) | 0 ≤ λ ≤ 1} are not orbits of a vector field. On the other hand, the nonlinear homotopy g ⁱ (s) = e ^s x ⁱ + (1—e ^s )y ⁱ ,—∞ ≤ s ≤ 0, are orbits of a vector field (i.e., dg ⁱ /ds = g ⁱ —y ⁱ , g ⁱ (0) = x ⁱ ), and thus have direct geometric significance. This suggests that useful results can be obtained by replacing linear homotopy by transport along flows of smooth vector fields. The purpose of this paper is to elaborate on this simple idea. We define prehomotopy operators induced by vector fields on a manifold. These allow us to obtain finite transport relations and pre-Poincaré lemmas that generalize the classical results. They are shown to reproduce the classical results as asymptotic limits and to obtain representations of all solutions of complete systems of exterior differential equations on a star shaped region of a manifold.     

ON DETECTION OF CHANGE POINTS USING MEAN VECTORS

In this paper,the authors consider the problem of change points within the framework of model selection and propose a procedure for estimating the locations of change points when the number of change points is known.The strong consistency of this procedure is also established. The problem of detecting change points is discussed within the framework of the simultaneous test procedure.The case where the number of change points is unknown will be discussed in another paper.     

INTERSECTION OF PRIME SUBMODULES AND DIMENSION OF MODULES

The aim of this paper is to study the conditions by which a P-prime submodule can be expressed as a finite intersection or union of P-prime submodules. Also corresponding to dimension and rank of modules, some equivalent conditions for a ring to be a Dedekind domain are given.     

OVERCONVERGENCE AND ZEROS OF SEQUENCES OF RATIONAL FUNCTIONS

In the present paper we consider sequences of rational functions with a bounded number or free poles con-verging uniformly with a maximum geometric rate to a holomorphic function on a regular set,and we examinethe limiting distribution of the Zeros and its relations with the phenomenon of overconvergence.Our resultsfurther extend the well known classical theory of overconvergence and the zeros of sections of Taylor series.     

THE INVARIANCE OF STRONG AND ALMOST SPIRALLIKE MAPPINGS OF TYPE β AND ORDER α

The invariance of strong and almost spirallike mappings of type β and order α is discussed in this paper.From the maximum modulus principle of holomorphic functions,we obtain that the generalized Roper-Suffridge operators preserve strong and almost spirallikeness of type β and order α on the unit ball B~n in C~n and on bounded and complete Reinhardt domains.Therefore we obtain that the generalized Roper-Suffridge operators preserve strong spirallikeness of type β,strong and almost starlikeness of order α,strong starlikeness on the corresponding domains.Thus we can construct more subclasses of spirallike mappings in several complex variables.     

BIFURCATION PROBLEMS OF MULTIPARAMETER AND MULTIBRANCH AND THEIR APPLICATIONS

This paper deals with the bifurcation problems of multiparameter and multibranch and their approximations. It derives general approximation results of solution branches in the neighbourhood of a singular (limit, turning or multibranch) point, and shows that turning and multibranch points are bifurcation points. The abstract theories are applied to a mixed finite element approximation of stationary Navier-Stokes equation.     

NECESSARY AND SUFFICIENT CONDITIONS OF EXISTENCE AND UNIQUENESS OF LIMIT CYCLES FOR A CLASS OF POLYNOMIAL SYSTEM

In this paper, we discuss the limit cycles of the systemdx/dt=y·[1+(A(x)]oy/dt=(-x+δy+α_1x~2+α_2xy+α_5x~2y)[1+B(x)] (1)where A(x)=sum form i=1 to n(a_ix~), B(x)=sum form j=1 to m(β_jx~j) and 1+B(x)>0. We prove that (1) possesses at most one limit cycle and give out the necessary and sufficient conditions of existence and uniqueness of limit cycles.     

CONVERGENCE OF CASCADE ALGORITHMS AND SMOOTHNESS OF REFINABLE DISTRIBUTIONS

In this paper, the author at first develops a method to study convergence of the cascade algorithm in a Banach space without stable assumption on the initial (see Theorem 2.1), and then applies the previous result on the convergence to characterizing compactly supported refinable distributions in fractional Sobolev spaces and Holder continuous spaces (see Theorems 3.1, 3.3, and 3.4). Finally the author applies the above characterization to choosing appropriate initial to guarantee the convergence of the cascade algorithm (see Theorem 4.2).     

DISCRETE ANALOGUES OF A THEOREM OF WINTNER AND HARTMAN

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EXTREMES OF RATIOS OF DETERMINANTS AND CANONICAL CORRELATION VARIABLES

This article develops some extremes of the ratios of determinants. The results are themultivariate extensions of the extremes of quadratic forms, and can be applied to finding thecanonicai correlation variables of two random vectors. Hence a group of canonical correlationvariables is a solution of the extreme of the ratio of determinants.     

NUMBERS OF CONJUGATE CLASSES OF SYMMETRIC AND ALTERNATING GROUPS

Let d(n)be the excess of the number of even conjugate classes of S_n over that of oddconjugate classes of S_n and q(n)the number of splitting classes of S_n.In this paper arecurrence formula for d(n)and one for q(n)are given.As a recurrence formula for thenumber p(n)of conjugate classes of S_n is known,one can make use of p(n),d(n)andq(n)to calculate the numbers of even(odd)conjugate classes of S_n and that of conjugateclasses of A_n.By means of a graphical method the author proves the identity d(n)=q(n)when n≥2,which seems to have been obtained first by Sylvester by use of generatingfunctions.     

DENSITY OF MARKOV SYSTEMS AND ZEROS OF CHEBYSHEV POLYNOMIALS

We raise and partly answer the question: whether there exists a Markov system with respectto which the zeros of the Chebyshev polynomials are dense, but the maximum length of a zerofree interval of the nth Chebyshev polynomial does not tends to zero. We also draw the conclu-tion that a Markov system, under an additional assumption, is dense if and only if the maxi-mum length of a zero free interval of the nth associated Chebyshev polynomial tends to zero.     

COLLISION AND MEETING OF STABLE PROCESSES

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ARBORICITY AND COMPLEMENT OF A GRAPH

1.IntroductionAllthegraphsweconsiderareundirectedandsimple.ThecompletegraphofordernisdenotedbyKm,anindependentsetofnvenicesbyK..ThenotationGUHmeans*ThisresearchissupportedbytheNationalNaturalScienceFoundationofChina.thedisjointunionoftwographsGandH,andG HthedisjointunionofGandHplusalltheedgesbetweenGandH,HSGindicatesthatHisasubgraphofG.or(G)istheindependentnumberofG,0(G)thecardinalofthemaximumcliqueofG.ThearboricityofagraphGistheminimumnumberofsubsetsilltowhichtheedgesetofGcanbepar…     

QUASI-MODULUS OF CONTINUITY AND BEST APPROXIMATIONS

In this paper a concept of the quasi-modulus of continuity of the functions of L^2(T) on the unit circle T is introduced, and the relations between it and modulus of continuity are discussed. And we give a sufficient condition such that the best uniform approxi marion of the continuous functions on T is continuous.     

SEMI-OPENNESS AND ALMOST-OPENNESS OF INDUCED MAPPINGS

Given a mapping f between continua. Let 2^f and C(f) mean the induced mappings between hyperspaces. Relations are studied under the conditions :f is semi-open (almost open, respectively), 2^f is semi-open (almost open, respectively) and C(f) is semi-open (almost open, respectively).