DSpace Collection: Volume 30 Number 1
http://hdl.handle.net/10525/1721
Serdica Mathematical Journal Volume 30, Number 1, 2004The Collection's search engineSearch the Channelsearch
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Sequences of Maximal Degree Vertices in Graphs
http://hdl.handle.net/10525/1729
Title: Sequences of Maximal Degree Vertices in Graphs<br/><br/>Authors: Khadzhiivanov, Nickolay; Nenov, Nedyalko<br/><br/>Abstract: Let Γ(M ) where M ⊂ V (G) be the set of all vertices of the graph G adjacent to any vertex of M.If v1, . . . , vr is a vertex sequence in G such that Γ(v1, . . . , vr ) = ∅ and vi is a maximal degree vertex in Γ(v1, . . . , vi−1),we prove that e(G) ≤ e(K(p1, . . . , pr)) where K(p1, . . . , pr ) is the complete r-partite graph with pi = |Γ(v1, . . . , vi−1) \ Γ(vi )|.<br/><br/>Description: 2000 Mathematics Subject Classification: 05C35.Zero-Dimensionality and Serre Rings
http://hdl.handle.net/10525/1728
Title: Zero-Dimensionality and Serre Rings<br/><br/>Authors: Karim, D.<br/><br/>Abstract: This paper deals with zero-dimensionality. We investigate the problem of whether a Serre ring R <X> is expressible as a directed unionof Artinian subrings.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 13A99; Secondary 13A15, 13B02, 13E05.Oscillation Criteria for First Order Delay Differential Equations
http://hdl.handle.net/10525/1727
Title: Oscillation Criteria for First Order Delay Differential Equations<br/><br/>Authors: Elabbasy, E.; Hassan, T.<br/><br/>Abstract: This paper is concerned with the oscillatory behavior of first-order delay differential equation of the form x'(t) + p(t)x (τ(t)) = 0.<br/><br/>Description: 2000 Mathematics Subject Classification: 34K15.Conditional Confidence Interval for the Scale Parameter of a Weibull Distribution
http://hdl.handle.net/10525/1726
Title: Conditional Confidence Interval for the Scale Parameter of a Weibull Distribution<br/><br/>Authors: Mahdi, Smail<br/><br/>Abstract: A two-sided conditional confidence interval for the scale parameter θ of a Weibull distribution is constructed. The construction follows the rejection of a preliminary test for the null hypothesis: θ = θ0 where θ0 is agiven value. The confidence bounds are derived according to the method setforth by Meeks and D’Agostino (1983) and subsequently used by Arabatzis etal. (1989) in Gaussian models and more recently by Chiou and Han (1994,1995) in exponential models. The derived conditional confidence intervalalso suits non large samples since it is based on the modified pivot statisticadvocated in Bain and Engelhardt (1981, 1991). The average length and thecoverage probability of this conditional interval are compared with whoseof the corresponding optimal unconditional interval through simulations.The study has shown that both intervals are similar when the populationscale parameter is far enough from θ0. However, when θ is in the vicinityof θ0, the conditional interval outperforms the unconditional one in termsof length and also maintains a reasonably high coverage probability. Ourresults agree with the findings of Chiou and Han and Arabatzis et al. whichcontrast with whose of Meeks and D’Agostino stating that the unconditionalinterval is always shorter than the conditional one. Furthermore, we derivedthe likelihood ratio confidence interval for θ and compared numerically itsperformance with the two other interval estimators.<br/><br/>Description: 2000 Mathematics Subject Classification: 62F25, 62F03.Weierstrass Points with First Non-Gap Four on a Double Covering of a Hyperelliptic Curve
http://hdl.handle.net/10525/1725
Title: Weierstrass Points with First Non-Gap Four on a Double Covering of a Hyperelliptic Curve<br/><br/>Authors: Komeda, Jiryo; Ohbuchi, Akira<br/><br/>Abstract: Let H be a 4-semigroup, i.e., a numerical semigroup whoseminimum positive element is four. We denote by 4r(H) + 2 the minimumelement of H which is congruent to 2 modulo 4. If the genus g of H islarger than 3r(H) − 1, then there is a cyclic covering π : C −→ P^1of curves with degree 4 and its ramification point P such that the Weierstrasssemigroup H(P) of P is H (Komeda [1]). In this paper it is showed that wecan construct a double covering of a hyperelliptic curve and its ramificationpoint P such that H(P) is equal to H even if g ≤ 3r(H) − 1.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 14H55; Secondary 14H30, 14H40, 20M14.Direct and Converse Theorems for Generalized Bernstein-Type Operators
http://hdl.handle.net/10525/1724
Title: Direct and Converse Theorems for Generalized Bernstein-Type Operators<br/><br/>Authors: Finta, Zoltán<br/><br/>Abstract: We establish direct and converse theorems for generalized parameter dependent Bernstein-type operators. The direct estimate is givenusing a K-functional and the inverse result is a strong converse inequalityof type A, in the terminology of [2].<br/><br/>Description: 2000 Mathematics Subject Classification: 41A25, 41A27, 41A36.Optimality Conditions for D.C. Vector Optimization Problems under D.C. Constraints
http://hdl.handle.net/10525/1723
Title: Optimality Conditions for D.C. Vector Optimization Problems under D.C. Constraints<br/><br/>Authors: Gadhi, N.; Metrane, A.<br/><br/>Abstract: In this paper, we establish necessary optimality conditions andsufficient optimality conditions for D.C. vector optimization problems underD.C. constraints. Under additional conditions, some results of [9] and [15]are also recovered.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 90C29; Secondary 49K30.Estimate for the Number of Zeros of Abelian Integrals on Elliptic Curves
http://hdl.handle.net/10525/1722
Title: Estimate for the Number of Zeros of Abelian Integrals on Elliptic Curves<br/><br/>Authors: Mihajlova, Ana<br/><br/>Abstract: We obtain an upper bound for the number ofzeros of the Abelian integral.<br/><br/>Description: 2000 Mathematics Subject Classification: Primary 34C07, secondary 34C08.