DSpace Community: 2005
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Rétractes Absolus de Voisinage Algébriques
http://hdl.handle.net/10525/1773
Title: Rétractes Absolus de Voisinage Algébriques<br/><br/>Authors: Cauty, Robert<br/><br/>Abstract: We introduce the class of algebraic ANRs. It is defined byreplacing continuous maps by chain mappings in Lefschetz’s characterization of ANRs. To a large extent, the theory of algebraic ANRs parallels the classical theory of ANRs. Every ANR is an algebraic ANR, but the class of algebraic ANRs is much larger; the most striking difference between these classes is that every locally equiconnected metrisable space is an algebraicANR, whereas there exist metric linear spaces which are not ARs. This is important for applications of topological fixed point theory to functional analysis because all known results of fixed point for compact maps of ANRsextend to the algebraic ANRs. We prove here two such generalizations: theLefschetz-Hopf fixed point theorem for compact maps of algebraic ANRs,and the fixed point theorem for compact upper semi-continuous multivalued maps with Q-acyclic compacts point images in a Q-acyclic algebraic ANR. We stress that these generalizations apply to all neighborhood retract of a metrisable linear space and, more generally, of a locally contractible metrisable group.<br/><br/>Description: 2000 Mathematics Subject Classification: 54C55, 54H25, 55M20.Quasi-Likelihood Estimation for Ornstein-Uhlenbeck Diffusion Observed at Random Time Points
http://hdl.handle.net/10525/1772
Title: Quasi-Likelihood Estimation for Ornstein-Uhlenbeck Diffusion Observed at Random Time Points<br/><br/>Authors: Adès, Michel; Dion, Jean-Pierre; MacGibbon, Brenda<br/><br/>Abstract: In this paper, we study the quasi-likelihood estimator of the drift parameter θ in the Ornstein-Uhlenbeck diffusion process, when theprocess is observed at random time points, which are assumed to be unobservable. These time points are arrival times of a Poisson process with known rate. The asymptotic properties of the quasi-likelihood estimator (QLE) of θ, as well as those of its approximations are also elucidated. An extensive simulation study of these estimators is also performed. As a corollary to this work, we obtain the quasi-likelihood estimator iteratively in the deterministic framework with non-equidistant time points.<br/><br/>Description: 2000 Mathematics Subject Classification: 60J60, 62M99.Necessary and Sufficient Condition for Oscillations of Neutral Differential Equation
http://hdl.handle.net/10525/1771
Title: Necessary and Sufficient Condition for Oscillations of Neutral Differential Equation<br/><br/>Authors: Elabbasy, E.; Hassan, T.; Saker, S.<br/><br/>Abstract: We obtain necessary and sufficient conditions for the oscillation of all solutions of neutral differential equation with mixed (delayed andadvanced) arguments ...<br/><br/>Description: 2000 Mathematics Subject Classification: 34K15, 34C10.Dispersive Estimates of Solutions to the Wave Equation with a Potential in Dimensions Two and Three
http://hdl.handle.net/10525/1770
Title: Dispersive Estimates of Solutions to the Wave Equation with a Potential in Dimensions Two and Three<br/><br/>Authors: Cardoso, Fernando; Cuevas, Claudio; Vodev, Georgi<br/><br/>Abstract: We prove dispersive estimates for solutions to the wave equation with a real-valued potential V.<br/><br/>Description: 2000 Mathematics Subject Classification: 35L15, 35B40, 47F05.Robust Parametric Estimation of Branching Processes with a Random Number of Ancestors
http://hdl.handle.net/10525/1768
Title: Robust Parametric Estimation of Branching Processes with a Random Number of Ancestors<br/><br/>Authors: Stoimenova, Vessela<br/><br/>Abstract: The paper deals with a robust parametric estimation in branching processes {Zt(n)} having a random number of ancestors Z0(n) as bothn and t tend to infinity (and thus Z0(n) in some sense). The offspring distribution is considered to belong to a discrete analogue of the exponential family – the class of the power series offspring distributions. Robust estimators, based on one and several sample paths, are proposed and studied for all values of the offspring mean m, 0 < m < ∞, in the subcritical, critical and supercritical case.<br/><br/>Description: 2000 Mathematics Subject Classification: 60J80.A Geometrical Construction for the Polynomial Invariants of some Reflection Groups
http://hdl.handle.net/10525/1767
Title: A Geometrical Construction for the Polynomial Invariants of some Reflection Groups<br/><br/>Authors: Sarti, Alessandra<br/><br/>Abstract: We construct invariant polynomials for the reflection groups[3, 4, 3] and [3, 3, 5] by using some special sets of lines on the quadric P1 × P1in P3. Then we give a simple proof of the well known fact that the ring ofinvariants are rationally generated in degree 2,6,8,12 and 2,12,20,30.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 20F55, 13F20; Secondary 14L30.Quaternion Extensions of Order 16
http://hdl.handle.net/10525/1766
Title: Quaternion Extensions of Order 16<br/><br/>Authors: Michailov, Ivo<br/><br/>Abstract: We describe several types of Galois extensions having as Galois group the quaternion group Q16 of order 16.<br/><br/>Description: 2000 Mathematics Subject Classification: 12F12On Root Arrangements of Polynomial-Like Functions and their Derivatives
http://hdl.handle.net/10525/1765
Title: On Root Arrangements of Polynomial-Like Functions and their Derivatives<br/><br/>Authors: Kostov, Vladimir<br/><br/>Abstract: We show that for n = 4 they are realizable eitherby hyperbolic polynomials of degree 4 or by non-hyperbolic polynomials ofdegree 6 whose fourth derivatives never vanish (these are a particular caseof the so-called hyperbolic polynomial-like functions of degree 4).<br/><br/>Description: 2000 Mathematics Subject Classification: 12D10.Recursive Methods for Construction of Balanced N-ary Block Designs
http://hdl.handle.net/10525/1764
Title: Recursive Methods for Construction of Balanced N-ary Block Designs<br/><br/>Authors: Gheribi-Aoulmi, Z.; Bousseboua, M.<br/><br/>Abstract: This paper presents a recursive method for the construction ofbalanced n-ary block designs.This method is based on the analogy between a balanced incompletebinary block design (B.I .E .B) and the set of all distinct linear sub-varieties ofthe same dimension extracted from a finite projective geometry. If V1is thefirst B.I .E .B resulting from this projective geometry, then by regarding anyblock of V1 as a projective geometry, we obtain another system of B.I .E .B.Then, by reproducing this operation a finite number of times, we get afamily of blocks made up of all obtained B.I .E .B blocks. The family beingpartially ordered, we can obtain an n-ary design in which the blocks areconsisted by the juxtaposition of all binary blocks completely nested. Thesen-ary designs are balanced and have well defined parameters. Moreover, aparticular balanced n-ary class is deduced with an appreciable reduction ofthe number of blocks.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 05B05; secondary 62K10.Projectively Normal Line Bundles on K-Gonal Curves and Rational Surfaces
http://hdl.handle.net/10525/1763
Title: Projectively Normal Line Bundles on K-Gonal Curves and Rational Surfaces<br/><br/>Authors: Ballico, E.; Keem, C.<br/><br/>Abstract: Here we prove the projective normality of several special linebundles on a general k-gonal curve.<br/><br/>Description: 2000 Mathematics Subject Classification: 14H50.Triangular Models and Asymptotics of Continuous Curves with Bounded and Unbounded Semigroup Generators
http://hdl.handle.net/10525/1761
Title: Triangular Models and Asymptotics of Continuous Curves with Bounded and Unbounded Semigroup Generators<br/><br/>Authors: Kirchev, Kiril; Borisova, Galina<br/><br/>Abstract: In this paper classes of K^r -operators are considered – the classes of bounded and unbounded operators A with equal domains of A and A*,finite dimensional imaginary parts and presented as a coupling of a dissipative operator and an antidissipative one with real absolutely continuousspectra and the class of unbounded dissipative K^r -operators A with different domains of A and A*and with real absolutely continuous spectra. Their triangular models are presented. The asymptotics of the corresponding continuous curves with generators from these classes are obtained in an explicit form. With the help of the obtained asymptotics the scattering theory forthe couples (A*, A) when A belongs to the introduced classes is constructed.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 47A48, Secondary 60G12.On the Convergence of (0,1,2) Interpolation
http://hdl.handle.net/10525/1760
Title: On the Convergence of (0,1,2) Interpolation<br/><br/>Authors: Muneer, Y.<br/><br/>Abstract: For the Hermite interpolation polynomial, Hm(x) we prove for any function f of C^(2q) ([−1, 1]) and any s = 0, 1, 2, . . . , q , where q is a fixed integer that ...<br/><br/>Description: 2000 Mathematics Subject Classification: 41A05.Weak Compatibility and Common Fixed Point Theorems for A-Contractive and E-expansive Maps in Uniform Spaces
http://hdl.handle.net/10525/1759
Title: Weak Compatibility and Common Fixed Point Theorems for A-Contractive and E-expansive Maps in Uniform Spaces<br/><br/>Authors: Aamri, M.; El Moutawakil, D.<br/><br/>Abstract: The purpose of this paper is to define the notion of A-distanceand E-distance in uniform spaces and give several new common fixed pointresults for weakly compatible contractive or expansive selfmappings of uniform spaces.<br/><br/>Description: 2000 Mathematics Subject Classification: 47H10, 54E15.An Invitation to Additive Prime Number Theory
http://hdl.handle.net/10525/1758
Title: An Invitation to Additive Prime Number Theory<br/><br/>Authors: Kumchev, A.; Tolev, D.<br/><br/>Abstract: The main purpose of this survey is to introduce the inexperienced reader to additive prime number theory and some related branchesof analytic number theory. We state the main problems in the field, sketchtheir history and the basic machinery used to study them, and try to give arepresentative sample of the directions of current research.<br/><br/>Description: 2000 Mathematics Subject Classification: 11D75, 11D85, 11L20, 11N05, 11N35, 11N36,11P05, 11P32, 11P55.