DSpace Collection: Volume 30 Number 4
http://hdl.handle.net/10525/1748
Serdica Mathematical Journal Volume 30, Number 4, 2004The Collection's search engineSearch the Channelsearch
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A Note on Elementary Derivations
http://hdl.handle.net/10525/1755
Title: A Note on Elementary Derivations<br/><br/>Authors: Khoury, Joseph<br/><br/>Abstract: Let R be a UFD containing a field of characteristic 0, andBm = R[Y1, . . . , Ym] be a polynomial ring over R. It was conjectured in [5]that if D is an R-elementary monomial derivation of B3 such that ker D isa finitely generated R-algebra then the generators of ker D can be chosen tobe linear in the Yi ’s. In this paper, we prove that this does not hold for B4.We also investigate R-elementary derivations D of Bm satisfying one or theother of the following conditions:(i) D is standard.(ii) ker D is generated over R by linear constants.(iii) D is fix-point-free.(iv) ker D is finitely generated as an R-algebra.(v) D is surjective.(vi) The rank of D is strictely less than m.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary: 14R10. Secondary: 14R20, 13N15.Thu, 01 Jan 2004 00:00:00 GMTRegular Averaging and Regular Extension Operators in Weakly Compact Subsets of Hilbert Spaces
http://hdl.handle.net/10525/1754
Title: Regular Averaging and Regular Extension Operators in Weakly Compact Subsets of Hilbert Spaces<br/><br/>Authors: Argyros, Spiros; Arvanitakis, Alexander<br/><br/>Abstract: For weakly compact subsets of Hilbert spaces K, we study theexistence of totally disconnected spaces L, such that C(K) is isomorphicto C(L). We prove that the space C(BH ) admits a Pełczyński decomposition andwe provide a starshaped weakly compact K, subset of BH with non-emptyinterior in the norm topology, and such that C(K) ~= C(L) with L totally disconnected.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 46E15, 54C55; Secondary 28B20.Thu, 01 Jan 2004 00:00:00 GMTInformation Matrix for Beta Distributions
http://hdl.handle.net/10525/1753
Title: Information Matrix for Beta Distributions<br/><br/>Authors: Aryal, Gokarna; Nadarajah, Saralees<br/><br/>Abstract: The Fisher information matrix for three generalized beta distributions are derived.<br/><br/>Description: 2000 Mathematics Subject Classification: 33C90, 62E99.Thu, 01 Jan 2004 00:00:00 GMTEssential Cover and Closure
http://hdl.handle.net/10525/1752
Title: Essential Cover and Closure<br/><br/>Authors: Andruszkiewicz, R.<br/><br/>Abstract: We construct some new examples showing that Heyman andRoos construction of the essential closure in the class of associative ringscan terminate at any finite or the first infinite ordinal.<br/><br/>Description: 2000 Mathematics Subject Classification: 16N80, 16S70, 16D25, 13G05.Thu, 01 Jan 2004 00:00:00 GMTSymmetric and Asymmetric Gaps in Some Fields of Formal Power Series
http://hdl.handle.net/10525/1751
Title: Symmetric and Asymmetric Gaps in Some Fields of Formal Power Series<br/><br/>Authors: Galanova, N.<br/><br/>Abstract: We consider a construction of fields with symmetric gaps that are not semi-η1. By this construction we give examples of fields with different asymmetric gaps.<br/><br/>Description: 2000 Mathematics Subject Classification: 03E04, 12J15, 12J25.Thu, 01 Jan 2004 00:00:00 GMTA Note on the Asymptotic Behaviour of a Periodic Multitype Galton-Watson Branching Process
http://hdl.handle.net/10525/1750
Title: A Note on the Asymptotic Behaviour of a Periodic Multitype Galton-Watson Branching Process<br/><br/>Authors: González, M.; Martínez, R.; Mota, M.<br/><br/>Abstract: In this work, the problem of the limiting behaviour of an irreducible Multitype Galton-Watson Branching Process with period d greaterthan 1 is considered. More specifically, almost sure convergence of somelinear functionals depending on d consecutive generations is studied underhypothesis of non extinction. As consequence the main parameters of themodel are given a convenient interpretation from a practical point of view.For a better understanding of the theoretical results, an illustrative exampleis provided.<br/><br/>Description: 2000 Mathematics Subject Classification: 60J80.Thu, 01 Jan 2004 00:00:00 GMTDirect and Inverse Spectral Problems for (2N + 1)-Diagonal, Complex, Symmetric, Non-Hermitian Matrices
http://hdl.handle.net/10525/1749
Title: Direct and Inverse Spectral Problems for (2N + 1)-Diagonal, Complex, Symmetric, Non-Hermitian Matrices<br/><br/>Authors: Zagorodnyuk, S.<br/><br/>Abstract: We give an easy procedure for solving of the direct and the inverse spectral problemsfor the equation. Guseynov used a procedure of the Gelfand-Levitan typefor the case N = 1. We use another procedure and this procedure is moreeasy and transparent.<br/><br/>Description: 2000 Mathematics Subject Classification: 42C05.Thu, 01 Jan 2004 00:00:00 GMT