DSpace Collection: Volume 29 Number 2
http://hdl.handle.net/10525/1698
Serdica Mathematical Journal Volume 29, Number 2, 2003The Collection's search engineSearch the Channelsearch
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On the Extinction Probability for Bisexual Branching Processes in Varying Environments
http://hdl.handle.net/10525/1706
Title: On the Extinction Probability for Bisexual Branching Processes in Varying Environments<br/><br/>Authors: Molina, Manuel; Mota, Manuel; Ramos, Alfonso<br/><br/>Abstract: In this paper, the bisexual branching process in varying environments introduced in [9] is considered and some sufficient conditions forthe existence of positive probability of non-extinction are established.<br/><br/>Description: 2000 Mathematics Subject Classification: 60J80Wed, 01 Jan 2003 00:00:00 GMTOn a Stratification Defined by Real Roots of Polynomials
http://hdl.handle.net/10525/1705
Title: On a Stratification Defined by Real Roots of Polynomials<br/><br/>Authors: Kostov, Vladimir<br/><br/>Abstract: We prove smoothnessof the strata and a transversality property of their tangent spaces.<br/><br/>Description: 2000 Mathematics Subject Classification: 12D10Wed, 01 Jan 2003 00:00:00 GMTDuality in Constrained DC-Optimization via Toland’s Duality Approach
http://hdl.handle.net/10525/1704
Title: Duality in Constrained DC-Optimization via Toland’s Duality Approach<br/><br/>Authors: Laghdir, M.; Benkenza, N.<br/><br/>Abstract: In this paper we reconsider a nonconvex duality theory established by B. Lemaire and M. Volle (see [4]), related to a primal problem ofminimizing the difference of two convex functions subject to a DC-constraint.The purpose of this note is to present a new method based on Toland-Singerduality principle. Applications to the case when the constraints are vector-valued are provided.<br/><br/>Description: 2000 Mathematics Subject Classification: 90C48, 49N15, 90C25Wed, 01 Jan 2003 00:00:00 GMTVariational Principles for Monotone and Maximal Bifunctions
http://hdl.handle.net/10525/1703
Title: Variational Principles for Monotone and Maximal Bifunctions<br/><br/>Authors: Chbani, Zaki; Riahi, Hassan<br/><br/>Abstract: We establish variational principles for monotone and maximalbifunctions of Brøndsted-Rockafellar type by using our characterization ofbifunction’s maximality in reflexive Banach spaces. As applications, we givean existence result of saddle point for convex-concave function and solve anapproximate inclusion governed by a maximal monotone operator.<br/><br/>Description: 2000 Mathematics Subject Classification: 49J40, 49J35, 58E30, 47H05Wed, 01 Jan 2003 00:00:00 GMTA Basis for Z-Graded Identities of Matrices over Infinite Fields
http://hdl.handle.net/10525/1702
Title: A Basis for Z-Graded Identities of Matrices over Infinite Fields<br/><br/>Authors: Azevedo, Sergio<br/><br/>Abstract: The algebra Mn(K) of the matrices n × n over a field K can be regarded as a Z-graded algebra. In this paper, it is proved that if K is aninfinite field, all the Z-graded polynomial identities of Mn(K) follow from the identities:x = 0, |α(x)| ≥ n,xy = yx, α(x) = α(y) = 0,xyz = zyx, α(x) = −α(y) = α(z ),where α is the degree of the corresponding variable. This is a generalization of a result of Vasilovsky about the Z-graded identities of the algebra Mn(K) over fields of characteristic 0.<br/><br/>Description: 2000 Mathematics Subject Classification: 16R10, 16R20, 16R50Wed, 01 Jan 2003 00:00:00 GMTApproximation of Lipschitz Mappings
http://hdl.handle.net/10525/1701
Title: Approximation of Lipschitz Mappings<br/><br/>Authors: Johanis, Michal<br/><br/>Abstract: We prove that any Lipschitz mapping from a separable Banach space into any Banach space can be approximated by uniformly Gâteaux differentiable Lipschitz mapping.<br/><br/>Description: 2000 Mathematics Subject Classification: 46B03Wed, 01 Jan 2003 00:00:00 GMTThe Operators Aγ = γA + -γA for a Class of Nondissipative Operators A with a Limit of the Corresponding Correlation Function
http://hdl.handle.net/10525/1700
Title: The Operators Aγ = γA + -γA for a Class of Nondissipative Operators A with a Limit of the Corresponding Correlation Function<br/><br/>Authors: Borisova, Galina<br/><br/>Abstract: In this work we present the operators Aγ = γA + -γA with Re γ = 1/2 in the case of an operator A from the class of nondissipative operators generating nonselfadjoint curves, whose correlation functions have a limit as t → ±∞. The asympthotics of the stationary curves e^(itAγ)f as t → ±∞ onto the absolutely continuous subspace of Aγ are obtained. These asymptotics and the obtained asymptotics in [9] of the nondissipative curves e^(itA)f allow to construct the scattering theory for the couples (Aγ , A) and (A, Aγ). We consider the basic terms from the scattering theory - wave operators, a scattering operator and the question of a similarity of A and Aγ. We obtain explicitly the wave operators, the scattering operator and the similarity of A and Aγ.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 47A48, Secondary 60G12Wed, 01 Jan 2003 00:00:00 GMTA Characterization of Weakly Lindelöf Determined Banach Spaces
http://hdl.handle.net/10525/1699
Title: A Characterization of Weakly Lindelöf Determined Banach Spaces<br/><br/>Authors: Kalenda, Ondřej<br/><br/>Abstract: We prove that a Banach space X is weakly Lindelöf determined if (and only if) each non-separable Banach space isomorphic to acomplemented subspace of X has a projectional resolution of the identity. This answers a question posed by S. Mercourakis and S. Negrepontis and yields a converse of Amir-Lindenstrauss’ theorem. We also prove that a Banach space of the form C(K) where K is a continuous image of a Valdivia compactum is weakly Lindelöf determined if (and only if) each non-separable Banach space isometric to a subspace of C(K) has a projectional resolution of the identity.<br/><br/>Description: 2000 Mathematics Subject Classification: 46B26, 46B03, 46B04.Wed, 01 Jan 2003 00:00:00 GMT