bluuebunny/crossref_metadata_2025_split huggingface dataset:
Irreducible subgroups of symplectic groups in characteristic 2
Authors: Parker Christopher , Rowley Peter 
Published: April 2009

AbstractSuppose that V is a finite dimensional vector space over a finite field of characteristic 2, G is the symplectic group on V and a is a non-zero vector of V. Here we classify irreducible subgroups of G containing a certain subgroup of O2(StabG(a)) all of whose non-trivial elements are 2-transvections.
Some classes of pseudo-BL algebras
Authors: Georgescu George , Leuştean Laurenţiu 
Published: April 2009

AbstractPseudo-BL algebras are noncommutative generalizations of BL-algebras and they include pseudo-MV algebras, a class of structures that are categorically equivalent to l-groups with strong unit. In this paper we characterize directly indecomposable pseudo-BL algebras and we define and study different classes of these structures: local, good, perfect, peculiar, and (strongly) bipartite pseudo-BL algebras.
On the mass formula of supersingular abelian varieties with real multiplications
Authors: Yu Chia-Fu 
Published: April 2009

AbstractA geometric mass concerning supersingular abelian varieties with real multiplications is formulated and related to an arithmetic mass. We determine the exact geometric mass formula for superspecial abelian varieties of Hubert-Blumenthal type. As an application, we compute the number of the irreducible components of the supersingular locus of some Hubert-Blumenthal varieties in terms of special values of the zeta function.
On Local Embedding Properties of Injectors of Finite Soluble Groups
Authors: Reifferscheid Stephanie 
Published: April 2009

AbstractIn the present paper we consider Fitting classes of finite soluble groups which locally satisfy additional conditions related to the behaviour of their injectors. More precisely, we study Fitting classes 1 ≠⊆such that an-injector of G is, respectively, a normal, (sub)modular, normally embedded, system permutable subgroup of G for all G ∈.Locally normal Fitting classes were studied before by various authors. Here we prove that some important results—already known for normality—are valid for all of the above mentioned embedding properties. For instance, all these embedding properties behave nicely with respect to the Lockett section. Further, for all of these properties the class of all finite soluble groups G such that an x-injector of G has the corresponding embedding property is not closed under forming normal products, and thus can fail to be a Fitting class.
On the completion of latin rectangles to symmetric latin squares
Authors: Bryant Darryn , Rodger C. A. 
Published: April 2009

AbstractWe find necessary and sufficient conditions for completing an arbitrary 2 by n latin rectangle to an n by n symmetric latin square, for completing an arbitrary 2 by n latin rectangle to an n by n unipotent symmetric latin square, and for completing an arbitrary 1 by n latin rectangle to an n by n idempotent symmetric latin square. Equivalently, we prove necessary and sufficient conditions for the existence of an (n−1)-edge colouring of Kn (n even), and for n-edge colouring of Kn (n odd) in which the colours assigned to the edges incident with two vertices are specified in advance.
Positive solutions of some quasilinear singular second order equations
Authors: Goncalves J. V. , Santos C. A. P. 
Published: April 2009

AbstractIn this paper we study the existence and uniqueness of positive solutions of boundary vlue problems for continuous semilinear perturbations, say f: [0, 1) × (0, ∞) → (0, ∞), of class of quasilinear operators which represent, for instance, the radial form of the Dirichlet problem on the unit ball of RN for the operators: p-Laplacian (1 < p < ∞) ad k-Hessian (1 ≤ k ≤ N). As a key feature, f (r, u) is possibly singular at r = 1 or u =0, Our approach exploits fixed point arguments and the Shooting Method.
Finite graphs of valency 4 and girth 4 admitting half-transitive group actions
Authors: Marušič Dragan , Nedela Roman 
Published: April 2009

AbstractFinite graphs of valency 4 and girth 4 admitting ½-transitive group actions, that is, vertex- and edge- but not arc-transitive group actions, are investigated. A graph is said to be ½-transitiveif its automorphism group acts ½-transitively. There is a natural orientation of the edge set of a ½-transitive graph induced and preserved by its automorphism group. It is proved that in a finite ½-transitive graph of valency 4 and girth 4 the set of 4-cycles decomposes the edge set in such a way that either every 4-cycle is alternating or every 4-cycle is directed relative to this orientation. In the latter case vertex stabilizers are isomorphic to Z2.
The Lindelöf principle and angular derivatives in convex domains of finite type
Authors: Abate Marco , Tauraso Roberto 
Published: April 2009

AbstractWe describe a generalization of the classical Julia-Wolff-Carathéodory theorem to a large class of bounded convex domains of finite type, including convex circular domains and convex domains with real analytic boundary. The main tools used in the proofs are several explicit estimates on the boundary behaviour of Kobayashi distance and metric, and a new Lindelöf principle.
The Schur and (weak) Dunford-Pettis properties in Banach lattices
Authors: Kamińska Anna , Mastyło Mieczysław 
Published: April 2009

AbstractWe study the Schur and (weak) Dunford-Pettis properties in Banach lattices. We show that l1, c0 and l∞ are the only Banach symmetric sequence spaces with the weak Dunford-Pettis property. We also characterize a large class of Banach lattices without the (weak) Dunford-Pettis property. In MusielakOrlicz sequence spaces we give some necessary and sufficient conditions for the Schur property, extending the Yamamuro result. We also present a number of results on the Schur property in weighted Orlicz sequence spaces, and, in particular, we find a complete characterization of this property for weights belonging to class ∧. We also present examples of weighted Orlicz spaces with the Schur property which are not L1-spaces. Finally, as an application of the results in sequence spaces, we provide a description of the weak Dunford-Pettis and the positive Schur properties in Orlicz spaces over an infinite non-atomic measure space.
Analyse conforme sur les algèbres de Jordan
Authors: Pevzner M. 
Published: April 2009

AbstractWe construct the Weil representation of the Kantor-Koecher-Tits Lie algebra g associated to a simple real Jordan algebraV. Later we introduce a family of integral operators intertwining the Weil representation with the infinitesimal representations of the degenerate principal series of the conformal groupGof the Jordan algebraV. The decomposition of L2(V) in the case of Jordan algebra of real square matrices is given using this construction.
On uniform bounds of primeness in matrix rings
Authors: Beidar Konstantin I. , Wisbauer Robert 
Published: April 2009

AbstractA subset S of an associative ring R is a uniform insulator for R provided a S b ≠ 0 for any nonzero a, b ∈ R. The ring R is called uniformly strongly prime of bound m if R has uniform insulators and the smallest of those has cardinality m. Here we compute these bounds for matrix rings over fields and obtain refinements of some results of van den Berg in this context.More precisely, for a field F and a positive integer k, let m be the bound of the matrix ring Mk(F), and let n be dimF(V), where V is a subspace of Mk(F) of maximal dimension with respect to not containing rank one matrices. We show that m + n = k2. This implies, for example, that n = k2 − k if and only if there exists a (nonassociative) division algebra over F of dimension k.
Composition operators in Orlicz spaces
Authors: Cui Yunan , Hudzik Henryk , Kumar Romesh , Maligranda Lech 
Published: April 2009

AbstractComposition operators Cτ between Orlicz spaces Lϕ (Ω, Σ, μ) generated by measurable and nonsingular transformations τ from Ω into itself are considered. We characterize boundedness and compactness of the composition operator between Orlicz spaces in terms of properties of the mapping τ, the function ϕ and the measure space (Ω, Σ, μ). These results generalize earlier results known for Lp-spaces.
The Exponential Representation of Holomorphic Functions of Uniformly Bounded Type
Authors: Quang Thai Thuan 
Published: April 2009

AbstractIt is shown that if E, F are Fréchet spaces, E ∈ (Hub), F ∈ (DN) then H(E, F) = Hub(E, F) holds. Using this result we prove that a Fréchet space E is nuclear and has the property (Hub) if and only if every entire function on E with values in a Fréchet space F ∈ (DN) can be represented in the exponential form. Moreover, it is also shown that if H(F*) has a LAERS and E ∈ (Hub) then H(E × F*) has a LAERS, where E, F are nuclear Fréchet spaces, F* has an absolute basis, and conversely, if H(E × F*) has a LAERS and F ∈ (DN) then E ∈ (Hub).
Nuclear and integral polynomials
Authors: Cilia Raffaella , Gutiérrez Joaquín M. 
Published: April 2009

AbstractLet E be a Banach space whose dual E* has the approximation property, and let m be an index. We show that E* has the Radon-Nikodým property if and only if every m-homogeneous integral polynomial from E into any Banach space is nuclear. We also obtain factorization and composition results for nuclear polynomials.
The generalized condition numbers of bounded linear operators in Banach spaces
Authors: Chen Guoliang , Wei Yimin , Xue Yifeng 
Published: April 2009

AbstractFor any bounded linear operator A in a Banach space, two generalized condition numbers, k(A) and k(A) are defined in this paper. These condition numbers may be applied to the perturbation analysis for the solution of ill-posed differential equations and bounded linear operator equations in infinite dimensional Banach spaces. Different expressions for the two generalized condition numbers are discussed in this paper and applied to the perturbation analysis of the operator equation.
Extremal partitions and distortion under the Montel bounded univalent maps
Authors: Vasil'ev Alexander 
Published: April 2009

AbstractExtremal partitions of domains into configurations of certain to pological form are studied. The extremal value of the weighted sum of reduced moduli of circular domains and digons is obtained. These results are applied to some problems about distortion under bounded conformal maps of the unit disk with two preassigned values.
Dense subsemigroups of generalised transformation semigroups
Authors: Wasanawichit Amorn , Kemprasit Yupaporn 
Published: April 2009

AbstractIn 1986, Higgins proved thatT(X), the semigroup (under composition) of all total transformations of a setX, has a proper dense subsemigroup if and only ifXis infinite, and he obtained similar results for partial and partial one-to-one transformations. We consider the generalised transformation semigroupT(X, Y) consisting of all total transformations fromXintoYunder the operation α * β = αθβ, where θ is any fixed element ofT(Y, X). We show that this semigroup has a proper dense subsemigroup if and only ifXandYare infinite and |Yθ| = min{|X|,|Y|}, and we obtain similar results for partial and partial one-to-one transformations. The results of Higgins then become special cases.
Some questions about rotundity and renormings in Banach spaces
Authors: Aizpuru A. , Garcia-Pacheco F. J. 
Published: April 2009

AbstractIn this paper, we show some results involving classical geometric concepts. For example, we characterize rotundity and Efimov-Stechkin property by mean of faces of the unit ball. Also, we prove that every almost locally uniformly rotund Banach space is locally uniformly rotund if its norm is Fréchet differentiable. Finally, we also provide some theorems in which we characterize the (strongly) exposed points of the unit ball using renormings.
Special involutions and bulky parabolic subgroups in finite Coxeter groups
Authors: Pfeiffer Götz , Röhrle Gerhard 
Published: April 2009

AbstractThe conjugacy classes of so-called special involutions parameterize the constituents of the action of a finite Coxeter group on the cohomology of the complement of its complexified hyperplane arrangement. In this note we give a short intrinsic characterisation of special involutions in terms of so-called bulky parabolic subgroups.
Duplication of Room squares
Authors: Wallis W. D. 
Published: April 2009

ARoom squareRof order 2nis a way of arranging 2nobjects (usually 1,2,…, 2n) in a square arrayRof side 2n– 1 so that:(i) every cell of the array is empty or contains two objects;(ii) each unordered pair of objects occurs once inR(iii) every row and column ofRcontains one copy of each object.
One-regular cubic graphs of order a small number times a prime or a prime square
Authors: Feng Yan-Quan , Kwak Jin Ho 
Published: April 2009

AbstractA graph is one-regular if its automorphism group acts regularly on the set of its arcs. In this paper we show that there exists a one-regular cubic graph of order 2p or 2p2 where p is a prime if and only if 3 is a divisor of p – 1 and the graph has order greater than 25. All of those one-regular cubic graphs are Cayley graphs on dihedral groups and there is only one such graph for each fixed order. Surprisingly, it can be shown that there is no one-regular cubic graph of order 4p or 4p2.
Posner's second theorem, multilinear polynomials and vanishing derivations
Authors: Filippis Vincenzo De , Vincenzo Onofrio Mario Di 
Published: April 2009

AbstractLet K be a commutative ring with unity, R a prime K-algebra of characteristic different from 2, d and δ non-zero derivations of R, f (x1,…, xn) a multilinear polynomial over K.Ifthen f(x1,…,xnis central-valued on R.
A note on the theta characteristics of a compact Riemann surface
Authors: Biswas Indranil 
Published: April 2009

AbstractLet X be a compact connected Riemann surface and ξ a square root of the holomorphic contangent bundle of X. Sending any line bundle L over X of order two to the image of dim H0(X, ξ ⊗ L) − dim H0(X, ξ) in Z/2Z defines a quadratic form on the space of all order two line bundles. We give a topological interpretation of this quadratic form in terms of index of vector fields on X.
Isometries between matrix algebras
Authors: Cheung Wai-Shun , Li Chi-Kwong , Poon Yiu-Tung 
Published: April 2009

AbstractAs an attempt to understand linear isometries between C*-algebras without the surjectivity assumption, we study linear isometries between matrix algebras. Denote by Mm the algebra of m × m complex matrices. If k ≥ n and φ: Mn → Mk has the form X ↦ U[X ⊕ f(X)] V or X ↦ U[X1 ⊕ f(X)]V for some unitary U, V ∈ Mk and contractive linear map f: Mn → Mk, then ║φ(X)║ = ║X║ for all X ∈ Mn. We prove that the converse is true if k ≤ 2n - 1, and the converse may fail if k ≥ 2n. Related results and questions involving positive linear maps and the numerical range are discussed.
Wavelet decomposition of Calderón-Zygmund operators on function spaces
Authors: Lau Ka-Sing , Yan Lixin 
Published: April 2009

AbstractWe make use of the Beylkin-Coifman-Rokhlin wavelet decomposition algorithm on the Calderón-Zygmund kernel to obtain some fine estimates on the operator and prove theT(l) theorem on Besov and Triebel-Lizorkin spaces. This extends previous results of Frazieret al., and Han and Hofmann.
Transitive simple subgroups of wreath products in product action
Authors: Baddeley Robert W. , Praeger Cheryl E. , Schneider Csaba 
Published: April 2009

AbstractA transitive simple subgroup of a finite symmetric group is very rarely contained in a full wreath product in product action. All such simple permutation groups are determined in this paper. This remarkable conclusion is reached after a definition and detailed examination of ‘Cartesian decompositions’ of the permuted set, relating them to certain ‘Cartesian systems of subgroups’. These concepts, and the bijective connections between them, are explored in greater generality, with specific future applications in mind.
Relatively compact-like perturbations, essential spectra and application
Authors: Latrach Khalid , Paoli J. Martin 
Published: April 2009

AbstractThe purpose of this paper is to provide a detailed treatment of the behaviour of essential spectra of closed densely defined linear operators subjected to additive perturbations not necessarily belonging to any ideal of the algebra of bounded linear operators. IfAdenotes a closed densely defined linear operator on a Banach spaceX, our approach consists principally in considering the class ofA-closable operators which, regarded as operators in ℒ(XA,X) (whereXAdenotes the domain ofAequipped with the graph norm), are contained in the set ofA-Fredholm perturbations (see Definition 1.2). Our results are used to describe the essential spectra of singular neutron transport equations in bounded geometries.
Real rank of C*-algebras associated with graphs
Authors: Jeong Ja A 
Published: April 2009

AbstractFor a locally finite directed graph E, it is known that the graph C*-algebra C*(E) has real rank zero if and only if the graph E satisfies the loop condition (K). In this paper we extend this to an arbitrary directed graph case using the desingularization of a graph due to Drinen and Tomforde
On the times of births in a linear birthprocess
Authors: Neuts Marcel F. , Resnick Sidney I. 
Published: April 2009

AbstractIf S1, S2,… are the times of successive births in a pure birth-process with linear birthrate and i > 0 individuals initially, then given that there are k > 0 births in (0, t), the random variables eλS1—1, eλS2−1,λS1−1 are distributed (conditionally) like the order statistics of k independent random variables, all uniformly distributed on the interval (0, eλt–1), regardless of the initial population size. A similar property holds for the pure death process.
Local hardy and BMO spaces on non-homogeneous spaces
Authors: Yang Dachun 
Published: April 2009

AbstractLet µ be Radon measure on Rd which may be non doubling. The only condition that µ must satisfy is the size condition µ(B(x, r)) ≤ Crn for some fixed n є (0, d). Recently, Tolsa introduced the spaces RBMO(µ) and Hatb1.∞ (µ), which, in some ways, play the role of the classical spaces BMO and H1 in case u is a doubling measure. In this paper, the author considers the local versions of the spaces RBMO(µ) and Hatb1.∞ (µ) in the sense of Goldberg and establishes the connections between the spaces RBMO(µ) and Hatb1.∞ (µ) with their local versions. An interpolation result of linear operators is also given.
Some new permutability properties of hypercentrally embedded subgroups of finite groups
Authors: Ezquerro L. M. , Soler-Escrivà X. 
Published: April 2009

AbstractHypercentrally embedded subgroups of finite groups can be characterized in terms of permutability as those subgroups which permute with all pronormal subgroups of the group. Despite that, in general, hypercentrally embedded subgroups do not permute with the intersection of pronormal subgroups, in this paper we prove that they permute with certain relevant types of subgroups which can be described as intersections of pronormal subgroups. We prove that hypercentrally embedded subgroups permute with subgroups of prefrattini type, which are intersections of maximal subgroups, and with F-normalizers, for a saturated formation F. In the soluble universe, F-normalizers can be described as intersection of some pronormal subgroups of the group.
Modules which are invariant under monomorphisms of their injective hulls
Authors: Alahmadi A. , Er N. , Jain S. K. 
Published: April 2009

AbstractIn this paper certain injectivity conditions in terms of extensions of monomorphisms are considered. In particular, it is proved that a ring R is a quasi-Frobenius ring if and only if every monomorphism from any essential right ideal of R into R(N)R can be extended to RR. Also, known results on pseudo-injective modules are extended. Dinh raised the question if a pseudo-injective CS module is quasi-injective. The following results are obtained: M is quasi-injective if and only if M is pseudo-injective and M2 is CS. Furthermore, if M is a direct sum of uniform modules, then M is quasi-injective if and only if M is pseudo-injective. As a consequence of this it is shown that over a right Noetherian ring R, quasi-injective modules are precisely pseudo-injective CS modules.
Partial automorphisms of stable C*-algebras and Hilbert C*-bimodules
Authors: Kodaka Kazunori 
Published: April 2009

AbstractLet A be a C*-algebra and K the C*-algebra of all compact operators on a countably infinite dimensional Hilbert space. In this note, we shall show that there is an isomorphism of a semigroup of equivalence classes of certain partial automorphisms of A ⊗ K onto a semigroup of equivalence classes of certain countably generated A-A-Hilbert bimodules.
Gradings of non-graded Hamiltonian Lie algebras
Authors: Caranti A. , Mattarei S. 
Published: April 2009

AbstractA thin Lie algebra is a Lie algebra graded over the positive integers satisfying a certain narrowness condition. We describe several cyclic grading of the modular Hamiltonian Lie algebrasH(2: n; ω2)(of dimension one less than a power ofp) from which we construct infinite-dimensional thin Lie algebras. In the process we provide an explicit identification ofH(2: n; ω2)with a Block algebra. We also compute its second cohomology group and its derivation algebra (in arbitrary prime characteristic).
Transient heat flow from a thin circular disk — small-time solution
Authors: Blackwell J. H. 
Published: April 2009

SummaryIn a previous paper [1] an approximate analytical solution, useful for large times, was obtained for the transient heat flow from a thin circular disk held at constant temperature and immersed in an infinite medium. In the present work a first approximation has been found for the complementary “small-time” solution and the details of this solution examined. Some numerical calculations are included.
Polarities and ovals in the Hughes plane
Authors: Room T. G. 
Published: April 2009

SummaryIn 1946 Baer (Polarities infinite projective planes, Bull. Am. Math. Soc. 52, 77–93) showed that the absolute points of a polarity in a finite projective plane of odd non-square order always form an oval, that is, in a plane of order n there are exactly n+ 1 absolute points and no three are collinear. It is well known that the absolute points of polarities in planes of odd square order form ovals in some cases.If the oval is a subset of the set of absolute points, then the oval itself determines the polarity, and this makes it appear unlikely that the oval could be a proper subset. Among other results in the paper it is to be proved that in the regular Hughes plane there is a polarity which is determined by an oval which is a relatively small subset of the set of absolute points. Explicitly, if Ω is the Hughes plane of order q2 and A is the central subplane of order q, then every conic in Δ can be extended to an oval in Ω, and this oval determines a polarity in which there are ½(q3–q) additional absolute points.
Partitions into large unequal parts from a general sequence
Authors: Fergusson Kevin John 
Published: April 2009

AbstractAn asymptotic estimate is obtained for the number of partitions of the positive integer n into unequal parts coming from a sequence u, with each part greater than m, under suitable conditions on the sequence u. The estimate holds uniformly with respect to integers m such that 0 ≤ m ≤ n1−δ, as n → ∞, where δ is a given real number, such that 0 < δ < 1.