bluuebunny/crossref_metadata_2025_split huggingface dataset:
About the zeros of some entire functions and their derivatives
Authors: Stoyanov Todor 
Published: April 2009

AbstractIn this article we localize the zeros of some polynomials and the derivatives of some entire functions of finite genus. If we put m = 1 in the condition of Theorem 1 we obtain the famous Obreshkoff Theorem which can be regarded as a ‘complex version’ of a well-known theorem due to Laguerre. The nonreal zeros of the derivative of the real entire funtion of Theorem 3 must belong to circles Vk which are similar to the Jen circles for polynomials.
Ergodic behaviour of extreme values
Authors: Cheng S. , Peng L. , Qi Y. 
Published: April 2009

AbstractLet {Xn, n ≥ 1} be independent identically distributed random variables with a common non-degenerate distribution function F. For each n ≥ 1, denote Mn = max {X1,…, Xn}. Under certain conditions on F, there exist constants an > 0 and bn ∈ R such that . In this paper, we shall show that {(Mn – bn)/an} exhibits ergodic behaviour under additional conditions of F.
Spectral and asymptotic properties of resolvent-dominated operators
Authors: Räbiger Frank , Wolff Manfred P. H. 
Published: April 2009

AbstractLet A and B be (not necessarily bounded) linear operators on a Banach lattice E such that |(s – B)-1x|≤ (s – A)-1|x| for all x in E and sufficiently large s ∈ R. The main purpose of this paper is to investigate the relation between the spectra σ(B) and σ(A) of B and A, respectively. We apply our results to study asymptotic properties of dominated C0-semigroups.
Sharkovskii's order and the stability of periodic points of maps of the interval
Authors: Zhang Guang Yuan , Li Qing Zhong 
Published: April 2009

AbstractLet f be a Cr (r ≥ 0) map from the interval [0, 1] into itself and m be a positive integer. This paper gives a sufficient and necessary condition under which the set of periodic points of period m disappears after a certain small Cr-perturbation.
Loomis-sikorski theorem for σ-complete MV-algebras and ℓ-groups
Authors: Dvurečenskij Anatolij 
Published: April 2009

AbstractWe show that every σ-complete MV-algebra is an MV-σ-homomorphic image of some σ-complete MV- algebra of fuzzy sets, called a tribe, which is a system of fuzzy sets of a crisp set Ω containing 1Ωand closed under fuzzy complementation and formation of min {∑nfn, 1}. Since a tribe is a direct generalization of a σ-algebra of crisp subsets, the representation theorem is an analogue of the Loomis-Sikorski theorem for MV-algebras. In addition, this result will be extended also for Dedekind σ-complete ℓ-groups with strong unit.
A solution of a problem of Plotkin and Vovsi and an application to varieties of groups
Authors: Gupta C. K. , Krasil'nikov A. N. 
Published: April 2009

AbstractLet K be an arbitrary field of characteristic 2, F a free group of countably infinite rank. We construct a finitely generated fully invariant subgroup U in F such that the relatively free group F/U satisfies the maximal condition on fully invariant subgroups but the group algebra K (F/U) does not satisfy the maximal condition on fully invariant ideals. This solves a problem posed by Plotkin and Vovsi. Using the developed techniques we also construct the first example of a non-finitely based (nilpotent of class 2)-by-(nilpotent of class 2) variety whose Abelian-by-(nilpotent of class at most 2) groups form a hereditarily finitely based subvariety.
Infinite time interval BSDEs and the convergence of g-martingales
Authors: Chen Zengjing , Wang Bo 
Published: April 2009

AbstractIn this paper, we first give a sufficient condition on the coefficients of a class of infinite time interval backward stochastic differential equations (BSDEs) under which the infinite time interval BSDEs have a unique solution for any given square integrable terminal value, and then, using the infinite time interval BSDEs, we study the convergence of g-martingales introduced by Peng via a kind of BSDEs. Finally, we study the applications of g-expectations and g-martingales in both finance and economics.
Self θ-congruent minimal surfaces in ℝ3
Authors: Chen Weihuan , Fang Yi 
Published: April 2009

AbstractA minimal surface is a surface with vanishing mean curvature. In this paper we study self θ -congruent minimal surfaces, that is, surfaces which are congruent to their θ-associates under rigid motions in R3 for 0 ≤ θ < 2π. We give necessary and sufficient conditions in terms of its Weierstrass pair for a surface to be self θ-congruent. We also construct some examples and give an application.
The embeddability of ring and semigroup amalgams is undecidable
Authors: Jackson Marcel 
Published: April 2009

AbstractWe prove that there is no algorithm to determine when an amalgam of finite rings (or semigroups) can be embedded in the class of rings or in the class of finite rings (respectively, in the class of semigroups or in the class of finite semigroups). These results are in marked contrast with the corresponding problems for groups where every amalgam of finite groups can be embedded in a finite group.
Transference on certain multilinear multiplier operators
Authors: Fan Dashan , Sato Shuichi 
Published: April 2009

AbstractWe study DeLeeuw type theorems for certain multilinear operators on the Lebesgue spaces and on the Hardy spaces. As applications, on the torus we obtain an analog of Lacey—Thiele's theorem on the bilinear Hilbert transform, as well as analogies of some recent theorems on multilinear singular integrals by Kenig—Stein and by Grafakos—Torres.
Sharp starlikeness conditions for analytic functions with bounded derivative
Authors: Rønning Frode , Ruscheweyh Stephan , Samaris Nikolas 
Published: April 2009

AbstractWe develop sharp conditions for various types of starlikeness for functions analytic in the unit disk with bounded derivatives. We also describe the precise range {zf′(z)/f(z): z ∈ D, f ∈ }, where f ∈ means f (0) = 0, f′(0) = 1, and |f′(z) - 1 |< ≦ λ in the unit disc D, and draw some cnoslusions from that.
Semidistributive inverse semigroups
Authors: Johnston-Thom Katherine G. , Jones Peter R. 
Published: April 2009

AbstractAn inverse semigroupSis said to be meet (join) semidistributive if its lattice(S) of full inverse subsemigroups is meet (join) semidistributive. We show that every meet (join) semidistributive inverse semigroup is in fact distributive.
Remarks on converse Carleman and Krein criteria for the classical moment problem
Authors: Pakes Anthony G. 
Published: April 2009

AbstractThe key theme is converse forms of criteria for deciding determinateness in the classical moment problem. A method of proof due to Koosis is streamlined and generalized giving a convexity condition under which moments satisfying implies that c a positive constant. A contrapositive version is proved under a rapid variation condition on f (x), generalizing a result of Lin. These results are used to obtain converses of the Stieltjes versions of the Carleman and Krein criteria. Hamburger versions are obtained which relax the symmetry assumption of Koosis and Lin, respectively. A sufficient condition for Stieltjes determinateness of a discrete law is given in terms of its mass function. These criteria are illustrated through several examples.
A problem of expressibility in some amalgamated products of groups
Authors: Faiziev Valerii 
Published: April 2009

AbstractLet S be a subset of a group G such that S−1 = S. Denote by gr (S) the subgroup of G generated by S, and by ls(g) the length of an element g ∈ gr(S) relative to the set S. Suppose that V is a finite subset of a free group F of countable rank such that the verbal subgroup V (F) is a proper subgroup of F. For an arbitrary group G, denote by (G) the set of values in G of all the words from the set V. In the present paper, for amalgamated products G = A *HB such that A ≠ H and the number of double cosets of B by H is at least three, the infiniteness of the set {ls(g) | g ∈ gr(S)}, where S = (G) ∪ (G)−1, is estabilished.
The characterisation of scoring functions
Authors: Deakin Michael A. B. 
Published: April 2009

AbstractThe literature on subjective probabilities contains a number of functions that have been proposed as ‘scoring functions’. The principal requirement is that, with several events that may occur in the future and to which subjective ‘probabilities’ are assigned, the expected score given by these ‘probabilities’ will be extremised if the values assigned equal the ‘true probabilities’ of the various outcomes. This article discusses the question of what other scoring functions might be used (beyond those so far proposed).
Multiplicity-free quotient tensor algebras
Authors: Wall G. E. 
Published: April 2009

AbstractLetVbe an infinite-dimensional vector space ovre a field of characteristic 0. It is well known that the tensor algebraTonVis a completely reducible module for the general linear groupGonV. This paper is concerned with those quotient algebrasAofTthat are at the same time modules forG. A partial solution is given to the problem of determinig thoseAin which no irreducible constitutent has multiplicity greater thatn 1.
Orbit sizes, local subgroups and chains of p-groups
Authors: Isaacs I. M. 
Published: April 2009

AbstractLet G be a finite group that acts on a finite group V, and let p be a prime that does not divide the order of V. Then the p-parts of the orbit sizes are the same in the actions of G on the sets of conjugacy classes and irreducible characters of V. This result is derived as a consequence of some general theory relating orbits and chains of p-subgroups of a group.
A note on multipliers of Lp(G, A)
Authors: Öztop Serap 
Published: April 2009

AbstractLet G be a locally compact abelian group, 1 < p < ∞, and A be a commutative Banach algebra. In this paper we study the space of multipliers on Lp (G, A) and characterize it as the space of multipliers of certain banach algebra. We also study the multipliers space on L1 (G, A) ∩ Lp (G, A).
Manifolds that fail to be co-dimension 2 fibrators necessarily cover themselves
Authors: Im Young Ho , Kim Yongkunk 
Published: April 2009

AbstractLetNbe a closeds-Hopfiann-manifold with residually finite, torsion free π1(N) and finiteH1(N). Suppose that either πk(N) is finitely generated for allk≥ 2, or πk(N) ≅ 0 for 1 <k<n– 1, orn≤ 4. We show that ifNfails to be a co-dimension 2 fibrator, thenNcyclically covers itself, up to homotopy type.
Generalized quasilinear hyperbolic equations and Yosida approximations
Authors: Park Jong Yeoul , Jung Il Hyo , Kang Yong Han 
Published: April 2009

AbstractWe will show the existence, uniqueness and regularity of global solutions for the Cauchy problem for nonlinear evolution equations with the damping term.As an application of our results, we give the global solvability and regularity of the mixed problem with Dirichiet boundary conditions:
Naturally reductive homogeneous real hypersurfaces in quaternionic space forms
Authors: Nagai Setsuo 
Published: April 2009

AbstractWe determine the naturally reductive homogeneous real hypersurfaces in the family of curvature-adapted real hypersurfaces in quaternionic projective space HPn(n ≥ 3). We conclude that the naturally reductive curvature-adapted real hypersurfaces in HPn are Q-quasiumbilical and vice-versa. Further, we study the same problem in quaternionic hyperbolic space HHn(n ≥ 3).
Biseparating linear maps between continuous vector-valued function spaces
Authors: Gau Haw-Long , Jeang Jyh-Shyang , Wong Nagi-Ching 
Published: April 2009

AbstractLet X, Y be compact Hausdorff spaces and E, F be Banach spaces. A linear map T: C(X, E) → C(Y, F) is separating if Tf, Tg have disjoint cozeroes whenever f, g have disjoint cozeroes. We prove that a biseparating linear bijection T (that is, T and T-1 are separating) is a weighted composition operator Tf = h · f o ϕ. Here, h is a function from Y into the set of invertible linear operators from E onto F, and ϕ, is a homeomorphism from Y onto X. We also show that T is bounded if and only if h(y) is a bounded operator from E onto F for all y in Y. In this case, h is continuous with respect to the strong operator topology.
Daisy structure in Desarguesian projective planes
Authors: Pardo M. Gabriela Araujo 
Published: April 2009

AbstractWe distribute the points and lines ofPG(2, 2n+1) according to a special structure that we call the daisy structure. This distribution is intimately related to a special block design which turns out to be isomorphic toPG(n, 2).We show a blocking set of 3qpoints inPG(2, 2n+1)that intersects each line in at least two points and we apply this to find a lower bound for the heterochromatic number of the projective plane.
Betti numbers of fixed point sets and multiplicities of indecomposable summands
Authors: Kaptanoglu Semra Öztürk 
Published: April 2009

AbstractLet G be a finite group of even order, k be a field of characteristic 2, and M be a finitely generated kG-module. If M is realized by a compact G-Moore space X, then the Betti numbers of the fixed point set XCn and the multiplicities of indecomposable summands of M considered as a kCn-module are related via a localization theorem in equivariant cohomology, where Cn is a cyclic subgroup of G of order n. Explicit formulas are given for n = 2 and n = 4.
Joint continuity of injective tensor products of vector measures in Banach lattices
Authors: Kawabe Jun 
Published: April 2009

AbstractIt is shown that the injective tensor product of positive vector measures in certain Banach lattices is jointly continuous with respect to the weak convergence of vector measures. This result is obtained by a diagonal convergence theorem for injective tensor integrals. Our approach to this problem is based on Bartle's bilinear integration theory.
On -hyperexcentric modules for Lie algebras
Authors: Barnes Donald W. 
Published: April 2009

AbstractLet be a saturated formation of soluble Lie algebras over the field F, and let L ∈ . Let V and W be -hypercentral and -hyperexcentric L-modules respectively. Then V ⊗FW and HomF(V, W) are -hyperexcentric and Hn(L, W) = 0 for all n.
Strange permutation representations of free groups
Authors: Bhattacharjee Meenaxi , MacPherson Dugald 
Published: April 2009

AbstractCertain permutation representations of free groups are constructed by finite approximation. The first is a construction of a cofinitary group with special properties, answering a question of Tim Wall published by Cameron. The second yields, via a method of Kepert and Willis, a totally disconnected locally compact group which is compactly generated and uniscalar but has no compact open normal subgroup. Finally, an oligomorphic group of automorphisms of the random graph is built, all of whose non-trivial subgroups have just finitely many orbits.
On permutation groups with constant movement
Authors: Alaeiyan(Khayaty) Mehdi 
Published: April 2009

AbstractLet G be a permutation group on a set Ω with no fixed point in Ω. If for each subset Г of Ω the size |Гg - Г| is bounded, for g ∈ G, we define the movement of g as the max|Гg − Г| over all subsets Г of Ω. In particular, if all non-identity elements of G have the same movement, then we say that G has constant movement. In this paper we will first give some families of groups with constant movement. We then classify all transitive permutation groups with a given constant movement m on a set of maximum size.
The Wielandt Subalgebra of a Lie Algebra
Authors: Barnes Donald W. , Groves Daniel 
Published: April 2009

AbstractFollowing the analogy with group theory, we define the Wielandt subalgebra of a finite-dimensional Lie algebra to be the intersection of the normalisers of the subnormal subalgebras. In a non-zero algebra, this is a non-zero ideal if the ground field has characteristic 0 or if the derived algebra is nilpotent, allowing the definition of the Wielandt series. For a Lie algebra with nilpotent derived algebra, we obtain a bound for the derived length in terms of the Wielandt length and show this bound to be best possible. We also characterise the Lie algebras with nilpotent derived algebra and Wielandt length 2.
An Embedding Construction for Ordered Groups
Authors: Mikaelian Vahagn H. 
Published: April 2009

AbstractGeneralizing and strengthening some well-known results of Higman, B. Neumann, Hanna Neumann and Dark on embeddings into two-generator groups, we introduce a construction of subnormal verbal embedding of an arbitrary (soluble, fully ordered or torsion free) ordered countable group into a twogenerator ordered group with these properties. Further, we establish subnormal verbal embedding of defect two of an arbitrary (soluble, fully ordered or torsion free) ordered group G into a group with these properties and of the same cardinality as G, and show in connection with a problem of Heineken that the defect of such an embedding cannot be made smaller, that is, such verbal embeddings of ordered groups cannot in general be normal.
Transferring Optimal Dualities: Theory and Practice
Authors: Davey B. A. , Haviar M. 
Published: April 2009

AbstractConsider the quasi-variety generated by a finite algebra and assume that yields a natural duality on based on which is optimal modulo endomorphisms. We shoe that, provided satisfies certain minimality conditions, we can transfer this duality to a natural duality on based on , which is also optimal modulo endormorphisms, for any finite algebra in that has a subalgebra isomorphic to .
On Products in Lattice-ordered Algebras
Authors: Boulabiar Karim 
Published: April 2009

AbstractLet A be a uniformly complete vector sublattice of an Archimedean semiprime f-algebra B and p ∈ {1, 2,…}. It is shown that the set ΠBp (A) = {f1 … fp: fk ∈ A, k = 1, …, p } is a uniformly complete vector sublattice of B. Moreover, if A is provided with an almost f-algebra multiplication * then there exists a positive operator Tp, from ΠBp(A) into A such that fi *…* fp = Tp(f1 …fp) for all f1…fp ∈ A.As application, being given a uniformly complete almost f-algebra (A, *) and a natural number p ≧ 3, the set Π*p(A) = {f1 *… *fp: fk ∈ A, k = 1…p} is a uniformly complete semiprime f-algebra under the ordering and the multiplication inherited from A.
The Direct Decomposition of l-algebras into Products of Subdirectly Irreducible Factors
Authors: Radeleczki Sándor 
Published: April 2009

AbstractGeneralizing earlier results of Katriňák, El-Assar and the present author we prove new structure theorems for l-algebras. We obtain necessary and sufficient conditions for the decomposition of an arbitrary bounded lattice into a direct product of (finitely) subdirectly irreducible lattices.
Banach-Dieudonné Theorem Revisited
Authors: Bruguera Montserrat , Martín-Peinador Elena 
Published: April 2009

AbstractWe prove that in the character group of an abelian topological group, the topology associated (in a standard way) to the continuous convergence structure is the finest of all those which induce the topology of simple convergence on the corresponding equicontinuous subsets. If the starting group is furthermore metrizable (or even almost metrizable), we obtain that such a topology coincides with the compact-open topology. This result constitutes a generalization of the theorem of Banach-Dieudonné, which is well known in the theory of locally convex spaces.We also characterize completeness, in the class of locally quasi-convex metrizable groups, by means of a property which we have calledthe quasi-convex compactness property, or brieflyqcp(Section 3).
Extreme Point Methods and Banach-Stone Theorems
Authors: Al-Halees Hasan , Fleming Richard J. 
Published: April 2009

AbstractAn operator is said to be nice if its conjugate maps extreme points of the dual unit ball to extreme points. The classical Banach-Stone Theorem says that an isometry from a space of continuous functions on a compact Hausdorff space onto another such space is a weighted composition operator. One common proof of this result uses the fact that an isometry is a nice operator. We use extreme point methods and the notion of centralizer to characterize nice operators as operator weighted compositions on subspaces of spaces of continuous functions with values in a Banach space. Previous characterizations of isometries from a subspace M of C0( Q, X) into C0(K, Y) require Y to be strictly convex, but we are able to obtain some results without that assumption. Important use is made of a vector-valued version of the Choquet Boundary. We also characterize nice operators from one function module to another.
Connectedness of graphs generated by a randomd-process
Authors: Ruciński A. , Wormald N. C. 
Published: April 2009

AbstractSuppose that a graph process begins withnisolated vertices, to which edges are added randomly one by one so that the maximum degree of the induced graph is always at mostd. In a previous article, the authors showed that asn→ ∞, with probability tending to 1, the result of this process is a d-regular graph. This graph is shown to be connected with probability asymptotic to 1.
The zeros of linear combinations of translates of polynomials
Authors: Walker Peter 
Published: April 2009

AbstractWe investigate the location and separation of zeros of certain three-term linear combination of translates of polynomials. In particular, we find an interval of the formI= [−1, 1 +h],h> 0 such that for a polynomialf, all of whose zeros are real, and λ ∈I, all zeros off(x+ 2ic) + 2λf(x) +f(x– 2ic) are also real.
On the distribution of harmonic measure on simply connected planar domains
Authors: Betsakos Dimitrios , Solynin Alexander Yu. 
Published: April 2009

AbstractFor a simply connected planar domain D with 0 ∈ D and dist(0, ∂D) = 1, let hD(r) be the harmonic measure of ∂ D ∩{|Z| ≤ r} evaluated at 0. The function hD(r) is the distribution of harmonic measure. It has been studied by B. L. Walden and L. A. Ward. We continue their study and answer some questions raised by them by constructing domains with pre-specified distribution.
Projective descriptions of the (LF)-spaces of type LB(λp(A), F)
Authors: Albanese Angela A. 
Published: April 2009

AbstractLet 1 < p < + ∞ or p = 0 and let A = (an)n be an increasing sequence of strictly positive weights on I. Let F be a Fréchet space. It is proved that if λp(A) satisfies the density condition of Heinrich and a certain condition (Ct) holds, then the (LF)-space LBi(λp(A), F) is a topological subspace of Lb(λp(A), F). It is also proved that these conditions are necessary provided F = λq(A) or F contains a complemented copy of Iq with 1 < p ≤ q < +∞.
A new approach to thek(GV)-problem
Authors: Keller Thomas Michael 
Published: April 2009

AbstractThis paper is concerned with the well-known and long-standingk(G V)-problem: If the finite groupGacts faithfully and irreducibly on the finiteGF(p)-moduleVandpdoes not divide the order ofG, is the numberk(GV) of conjugacy classes of the semidirect productGVbounded above by the order ofV? Over the past two decades, through the work of numerous people, by using deep character theoretic arguments this question has been answered in the affirmative except for ρ = 5 for which it is still open. In this paper we suggest a new approach to thek(G V)-problem which is independent of most of the previous work on the problem and which is mainly group theoretical. To demonstrate the potential of the new line of attack we use it to solve thek(G V)-problem for solvableGand large ρ.
Correspondences of the Gelfand invariants in reductive dual pairs
Authors: Itoh Minoru 
Published: April 2009

AbstractFor each complex reductive dual pair introduced by R. Howe, this paper presents a formula for the central elements of the universal enveloping algebras given by I. M. Gelfand. This formula provides an explicit description of the correspondence between the ‘centers’ of the two universal enveloping algebras.
Mono-unary algebras are strongly dualizable
Authors: Hyndman Jennifer 
Published: April 2009

AbstractWe show that mono-unary algebras have rank at most two and are thus strongly dualizable. We provide an example of a strong duality for a mono-unary algebra using an alter ego with (partial) operations of arity at most two. This mono-unary algebra has rank two and generates the same quasivariety as an injective, hence rank one, mono-unary algebra.