bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hahn-Banach Type Theorems for Locally Convex Cones
Authors: Roth Walter 
Published: April 2009

AbstractWe prove Hahn-Banach type theorems for linear functionals with values in R∪{+∞} on ordered cones, Using the concept of locally convex cones, we provide a sandwich theorem involving sub- and superlinear functionals which are allowed to attain infinite values. It render general versions of well-known extension and separation results. We describe the range of all linear functionals sandwiched between given sub- and superlinear functionals on an ordered cone. The results are of interest even in vector spaces, since we consider sublinear functionals that may attain the value +∞.
On Symmetric Quasicircles
Authors: Wu Shengjian , Yang Shanshuang 
Published: April 2009

AbstractWe study an important subclass of quasicircles, namely, symmetric quasicircles. Several characterizations for quasicircles, such as the reverse triangle inequality, the M -condition and the quasiconformal extension property, have been extended to symmetric quasicircles by Becker and Pommerenke and by Gardiner and Sullivan. In this paper we establish several relations among various domain constants such as quasiextremal distance constants, (local) reflection constants and (local) extension constants for this class. We also give several characterizations for symmetric quasicircles such as the strong quadrilateral inequality and the strong extremal distance property. They correspond to the quadrilateral inequality and the extremal distance property for quasicircles.
Euler Characteristics and imbeddings of hyperbolic Coxeter groups
Authors: Maxwell George 
Published: April 2009

AbstractThis paper has a twofold purpose. The first is to compute the Euler characteristics of hyperbolic Coxeter groups Ws of level 1 or 2 by a mixture of theoretical and computer aided methods. For groups of level 1 and odd values of |S|, the Euler characteristic is related to the volume of the fundamental region of Ws in hyperbolic space. Secondly we note two methods of imbedding such groups in each other. This reduces the amount of computation needed to determine the Euler characteristics and also reduces the number of essentially different hyperbolic groups that need to be considered.
On certain pairs of automorphisms of rings, II
Authors: Brešar Matej 
Published: April 2009

AbstractLet R be a prime ring of characteristic not 2. Automorphisms α and β of R satisfying α ≠ β, α ≠ β−1, and α + α−1 = β + β-1 are characterized. This result is an algebraic analogue of some results for operator algebras.
Some properties of quasiuniform multifunction spaces
Authors: Cao Jiling , Reilly Ivan L. , Romaguera Salvador 
Published: April 2009

AbstractThe aim of this paper is to explore some properties of quasiuniform multifunction spaces. Various kinds of completeness of the quasiuniform multifunction space (YmX, UmX) are characterized in terms of suitable properties of the range space (Y, U). We also discuss the local compactness of quasiuniform multifunction spaces. By using the notion of small-set symmetry, the classic result of Hunsaker and Naimpally is extended to the quasiuniform setting.
The singular ideal and radicals
Authors: Ferrero Miguel , Puczyłowski Edmund R. 
Published: April 2009

AbstractSome properties of the singular ideal are established. In particular its behaviour when passing to one-sided ideals is studied. Obtained results are applied to study some radicals related to the singular ideal. In particular a radical S such that for every ring R, S(R) and R/S(R) are close to being a singular ring and a non-singular ring, respectively, is constructed.
T-regular probabilistic convergence spaces
Authors: Minkler J. , Minkler G. , Richardson G. 
Published: April 2009

AbstractA probabilistic convergence structure assigns a probability that a given filter converges to a given element of the space. The role of the t-norm (triangle norm) in the study of regularity of probabilistic convergence spaces is investigated. Given a probabilistic convergence space, there exists a finest T-regular space which is coarser than the given space, and is referred to as the ‘T-regular modification’. Moreover, for each probabilistic convergence space, there is a sequence of spaces, indexed by nonnegative ordinals, whose first term is the given space and whose last term is its T-regular modification. The T-regular modification is illustrated in the example involving ‘convergence with probability λ’ for several t-norms. Suitable function space structures in terms of a given t-norm are also considered.
Ergodicity and differences of functions on semigroups
Authors: Basit Bolis , Pryde A. J. 
Published: April 2009

AbstractIseki [11] defined a general notion of ergodicity suitable for functions ϕ: J → X where J is an arbitrary abelian semigroup and X is a Banach space. In this paper we develop the theory of such functions, showing in particular that it fits the general framework established by Eberlein [9] for ergodicity of semigroups of operators acting on X. Moreover, let A be a translation invariant closed subspace of the space of all bounded functions from J to X. We prove that if A contains the constant functions and ϕ is an ergodic function whose differences lie in A then ϕ ∈ A. This result has applications to spaces of sequences facilitating new proofs of theorems of Gelfand and Katznelson-Tzafriri [12]. We also obtain a decomposition for the space of ergodic vectors of a representation T: J → L(X) generalizing results known for the case J = Z+. Finally, when J is a subsemigroup of a locally compact abelian group G, we compare the Iseki integrals with the better known Cesàro integrals.
Compactness properties for perturbed semigroups and application to transport equation
Authors: Latrach Khalid 
Published: April 2009

AbstractUsing the comparsion results for positive compact operators by Aliprantis and Burkinshow, Mokhtar Kharroubi investigated cimpactness properties of positive semigroups on Banach latttices. The aim of this paper is to study these properties in general Banach spaces (without positivity). Our results generalize a part fo those obtained by Mokhtar-Kharroubi to general Banach spaces context. More specifically, we derive conditions which ensure the compactness of the remainder term Rn(t) for some inteter n. The improvement here is that it can applied directly to the neutron transport equation for a wide class of collision operators.
Weighted composition operators in weighted Banach spaces of analytic functions
Authors: Contreras M. D. , Hernandez-Diaz A. G. 
Published: April 2009

AbstractWe characterize the boundedness and compactness of weighted composition operators between weighted Banach spaces of analytic functionsand. we estimate the essential norm of a weighted composition operator and compute it for those Banach spaceswhich are isomorphic toc0. We also show that, when such an operator is not compact, it is an isomorphism on a subspace isomorphic toc0orl∞. Finally, we apply these results to study composition operators between Bloch type spaces and little Bloch type spaces.
Pointwise estimates of the size of characters of compact Lie groups
Authors: Hare Kathryn E. , Wilson David C. , Yee Wai Ling 
Published: April 2009

AbstractPointwise bounds for characters of representations of the classical, compact, connected, simple Lie groups are obtained with which allow us to study the singularity of central measures. For example, we find the minimal integer k such that any continuous orbital measure convolved with itself k times belongs to L2. We also prove that if k = rank G then μ 2k ∈ L1 for all central, continuous measures μ. This improves upon the known classical result which required the exponent to be dimension of the group G.
Theta series liftings from orthogonal groups to semi-simple groups
Authors: Lee Min Ho 
Published: April 2009

AbstractWe study a correspondence between automorphic forms on an orthogonal group and automorpbic forms on a semi-simple Lie group associated to an equivariant holomorphic map of a symmetric domain into a Siegel upper half space. We construct an automorphic form on the symmetric domain thatg corresponds to an automorphic form on an orthogonal group using theta series, and prove that such a correspondence is compatible with the appropriate Hecks operator actions on the corresponding automorphic forms. As an example, we describe the case of spin groups.
Stability and constant boundary-value problems of harmonic maps with potential
Authors: Chen Qun 
Published: April 2009

AbstractLet M, N be Riemannian manifolds, f: M → N a harmonic map with potential H, namely, a smooth critical point of the functional EH(f) = ∫M[e(f)−H(f)], where e(f) is the energy density of f. Some results concerning the stability of these maps between spheres and any Riemannian manifold are given. For a general class of M, this paper also gives a result on the constant boundary-value problem which generalizes the result of Karcher-Wood even in the case of the usual harmonic maps. It can also be applied to the static Landau-Lifshitz equations.
Automatic continuity and second order cohomology
Authors: Runde Volker 
Published: April 2009

AbstractMany Banach algebrasAhave the property that, although there are discontinuous homomorphisms fromAinto other Banach algebras, every homomorphism fromAinto another Banach algebra is automatically continuous on a dense subspace—preferably, a subalgebra—ofA. Examples of such algebras areC*-algebras and the group algebrasL1(G), whereGis a locally compact, abelian group. In this paper, we prove analogous results for, whereEis a Banach space, and. An important rôle is played by the second Hochschild cohomology group ofand, respectively, with coefficients in the one-dimensional annihilator module. It vanishes in the first case and has linear dimension one in the second one.
Finitely generated residually torsion-free nilpotent groups. I
Authors: Baumslag Gilbert 
Published: April 2009

AbstractThe object of this paper is to study the sequence of torsion-free ranks of the quotients by the terms of the lower central series of a finitely generated group. This gives rise to the introduction into the study of finitely generated, residually torison-free nilpotent groups of notions relating to the Gelfand-Kirillov dimension. These notions are explored here. The main result concerning the sequences alluded to is the proof that there are continuously many such sequences.
Endoprimal abelian groups
Authors: Kaarli Kalle , Márki László 
Published: April 2009

AbstractA group A is said to be endoprimal if its term functions are precisely the functions which permute with all endomorphisms of A. In this paper we describe endoprimal groups in the following three classes of abelian groups: torsion groups, torsionfree groups of rank at most 2, direct sums of a torsion group and a torsionfree group of rank 1.
Non-wandering points and the depth of a graph map
Authors: Ye Xiangdong 
Published: April 2009

AbstractLef: G → G be a continuous map of a graph and let d(A) denote the derived set (or limit points) of A ⊂ G. We prove that d(Ω(f)) ⊂ λ (f) and the depth of f is at most three. We also prove that if f is piecewise monotone or has zero topological entropy, then the depth of f is at most two. Furthermore, we obtain some results on the topological structure of Ω(f).
Tameness and geodesic cores of subgroups
Authors: Gitik Rita 
Published: April 2009

AbstractLet N be a finitely generated normal subgroup of a finitely generated group G. We show that if the trivial subgroup is tame in the factor group G/N, then N is that in G. We also give a short new proof of the fact that quasiconvex subgroups of negatively curved groups are tame. The proof utilizes the concept of the geodesic core of the subgroup and is related to the Dehn algorithm.
Equivalence of certain categories of modules for quantized affine lie algebras
Authors: Futorny Vyacheslav M. , Melville Duncan J. 
Published: April 2009

AbstractWe show that a quantum Verma-type module for a quantum group associated to an affine Kac-Moody algebra is characterized by its subspace of finite-dimensional weight spaces. In order to do this we prove an explicit equivalence of categories between a certain category containing the quantum Verma modules and a category of modules for a subalgebra of the quantum group for which the finite part of the Verma module is itself a module.
Integration maps and local equicontinuity of spectral measures
Authors: Okada S. , Ricker W. J. 
Published: April 2009

AbstractOne of the useful features of spectral measures which happen to be equicontinuous is that their associated integration maps are bicontinuous isomorphisms of the corresponding L1-space onto their ranges. It is shown here that equicontinuity is not necessary for this to be the case; a somewhat weaker property suffices. This is of some interest in practice since there are many natural examples of spectral measures which fail to be equiconontinuous.
Nonsmooth critical point theory and nonlinear elliptic equations at resonance
Authors: Kourogenis Nikolaos C. , Papageorgiou Nikolaos S. 
Published: April 2009

AbstractIn this paper we complete two tasks. First we extend the nonsmooth critical point theory of Chang to the case where the energy functional satisfies only the weaker nonsmooth Cerami condition and we also relax the boundary conditions. Then we study semilinear and quasilinear equations (involving the p-Laplacian). Using a variational approach we establish the existence of one and of multiple solutions. In simple existence theorems, we allow the right hand side to be discontinuous. In that case in order to have an existence theory, we pass to a multivalued approximation of the original problem by, roughly speaking, filling in the gaps at the discontinuity points.
On profinite groups in which commutators are Engel
Authors: Shumyatsky Pavel 
Published: April 2009

AbstractWe show that if G is a finitely generated profinite group such that [x1, x2, …, xk] is Engel for any x1, x2, …, xk ∈ G, then γ(G) is locally nilpotent, and if [x1, x2, …, xk] has finite order for any x1, x2, …, xk ∈ G then, under some additional assumptions, γk(G) is locally finite.
Path properties of the primitives of a Brownian motion
Authors: Lin Zhengyan 
Published: April 2009

AbstractLet {W(t),t≥ 0} be a standard Brownian motion. For a positive integerm, define a Gaussian processWatanabe and Lachal gave some asymptotic properties of the processXm(·),m≥ 1. In this paper, we study the bounds of its moduli of continuity and large increments by establishing large deviation results.
Remarks concerning finitely generated semigroups having regular sets of unique normal forms
Authors: Cutting Andrew , Solomon Andrew 
Published: April 2009

AbstractProperties such as automaticity, growth and decidability are investigated for the class of finitely generated semigroups which have regular sets of unique normal forms. Knowledge obtained is then applied to the task of demonstrating that a class of semigroups derived from free inverse semigroups under certain closure operations is not automatic.
The torsion of the group of homeomorphisms of powers of the long line
Authors: Deo Satya , Gauld David 
Published: April 2009

AbstractBy blending techniques from set theory and algebraic topology we investigate the order of any homeomorphism of the nth power of the long ray or long line L having finite order, finding all possible orders when n = 1, 2, 3 or 4 in the first case and when n = 1 or 2 in the second. We also show that all finite powers of L are acyclic with respect to Alexander-Spanier cohomology.
Diameter-preserving linear bijections of function spaces
Authors: Rao T. S. S. R. K. , Roy A. K. 
Published: April 2009

AbstractIn this paper we give a complete description of diameter-preserving linear bijections on the space of affine continuous functions on a compact convex set whose extreme points are split faces. We also give a description of such maps on function algebras considered on their maximal ideal space. We formulate and prove similar results for spaces of vector-valued functions.
Minimum sized fibres in distributive lattices
Authors: Duffus Dwight , Sands Bill 
Published: April 2009

AbstractA subset F of an ordered set X is a fibre of X if F intersects every maximal antichain of X. We find a lower bound on the function ƒ (D), the minimum fibre size in the distributive lattice D, in terms of the size of D. In particular, we prove that there is a constant c such that In the process we show that minimum fibre size is a monotone property for a certain class of distributive lattices. This fact depends upon being able to split every maximal antichain of this class of distributive lattices into two parts so that the lattice is the union of the upset of one part and the downset of the other.
A generalisation of the Morse inequalities
Authors: Bhupal Mohan 
Published: April 2009

AbstractIn this paper we construct a family of variational families for a Legendrian embedding, into the 1-jet bundle of a closed manifold, that can be obtained from the zero section through Legendrian embdeddings, by discretising the action functional. We compute the second variation of a generating funciton obtained as above at a nondegenerate critical point and prove a formula relating the signature of the second variation to the Maslov index as the mesh goes to zero. We use this to prove a generlisation of the Morse inequalities thus refining a theorem of Chekanov.
Unique Hahn-Banach theorems for spaces of homogeneous polynomials
Authors: Aron R. , Boyd C. , Choi Y. S. 
Published: April 2009

AbstractWe investigate certain norm and continuity conditions that provide us with ‘uniqe Hahn-Banch Theorems’ from (nc0) to (nℓ∞) and from N(nE) to N(nE″). We show that there is a unique norm-preserving extension for norm-attaining 2-homogeneous polynomials on complex c0 to ℓ∈ but there is no unique norm-preserving extension from (3c0) to (3ℓ∈).
Fractional parts of Linear polynomials and an application to hypergeometric functions
Authors: Dvornicich Roberto , Zannier Umberto 
Published: April 2009

AbstractUsing a result on arithmetic progressions, we describe a method for finding the rational h–tuples ρ = (ρl,…,ρh) such that all the multiples mρ (for m coprime to a denominator of ρ) lie in a linear variety modulo Z. We give an application to hypergeometric functions.
On Banach-Mazur compacta
Authors: Ageev Sergei M. , Repovŝ Duŝan 
Published: April 2009

AbstractWe study Banach-Mazur compacta Q(n), that is, the sets of all isometry classes of n-dimensional Banach spaces topologized by the Banach-Mazur metric. Our main result is that Q(2) is homeomorphic to the compactification of a Hilbert cube manifold by a point, for we prove that Qg(2) = Q(2) / {Eucl.} is a Hilbert cube manifold. As a corollary it follows that Q(2) is not homogeneous.
Estimation and filtering of fractional generalised random fields
Authors: Angulo J. M. , Ruiz-Medina M. D. , Anh V. V. 
Published: April 2009

AbstractThis paper considers the estimation and filtering of fractional random fields, of which fractional Brownian motion and fractional Riesz-Bessel motion are important special cases. A least-squares solution to the problem is derived by using the duality theory and covariance factorisation of fractional generalised random fields. The minimum fractional duality order of the information random field leads to the most general class of solutions corresponding to the largest function space where the output random field can be approximated. The second-order properties that define the class of random fields for which the least-squares linear estimation problem is solved in a weak-sense are also investigated in terms of the covariance spectrum of the information random field.
Norm inequalities relating one-sided singular integrals and the one-sided maximal function
Authors: Riveros M. S. , de la Torre A. 
Published: April 2009

AbstractIn this paper we prove that if a weight w satisfies the condition, then the Lp(w) norm of a one-sided singular integral is bounded by the Lp(w) norm of the one-sided Hardy-Littlewood maximal function, for 1 < p < q < ∞.
Locally graded groups with a nilpotency condition on infinite subsets
Authors: Delizia Costantino , Rhemtulla Akbar , Smith Howard 
Published: April 2009

AbstractA group G is locally graded if every finitely generated nontrivial subgroup of G has a nontrivial finite image. Let N (2, k)* denote the class of groups in which every infinite subset contains a pair of elements that generate a nilpotent subgroup of class at most k. We show that if G is a finitely generated locally graded N (2, k)*-group, then there is a positive integer c depending only on k such that G/Zc (G) is finite.
Composition operators on Qp spaces
Authors: Lou Zengjian 
Published: April 2009

AbstractA holomorphic map ψ of the unit disk ito itself induces an operator Cψ on holomorphic functions by composition. We characterize bounded and compact composition operators Cψ on Qp spaces, which coincide with the BMOA for p = 1 and Bloch spaces for p > 1. We also give boundedness and compactness characterizations of Cψ from analytic function space X to Qp spaces, X = Dirichlet space D, Bloch space B or B0 = {f: f′ ∈ H∞}.
The perturbation theory for the Drazin inverse and its applications II
Authors: Rakočevič Vladimir , Wei Yimin 
Published: April 2009

AbstractWe study the perturbation of the generalized Drazin inverse for the elements of Banach algebras and bounded linear operators on Banach space. This work, among other things, extends the results obtained by the second author and Guorong Wang on the Drazin inverse for matrices.
Essentially commutative C*-algebras with essential spectrum homeomorphic to S2n−1
Authors: Guo Kunyu 
Published: April 2009

AbstractThis paper gives a complete classification of essentially commutative C*-algebras whose essential spectrum is homeomorphic to S2n−1 by their characteristic numbers. Let 1, 2 be such two C*-algebras; then they are C*-isomorphic if and only if they have the same n-th characteristic number. Furthermore, let γn() = m then is C*-isomorphic to C*(Mzl, …, Mzn) if m = 0, is C*-isomorphic C*(Tz1, …, Tzn−1, Tznm) if m ≠ 0. Some examples are given to show applications of the classfication theorem. We finally remark that the proof of the theorem depends on a construction of a complete system of representatives of Ext(S2n−1).
Dual characterizations of relative continuity of convex functions
Authors: Benoist J. , Daniilidis A. 
Published: April 2009

AbstractVarious properties of continuity for the class of lower semicontinuous convex functions are considered and dual characterizations are established. In particular, it is shown that the restriction of a lower semicontinuous convex function to its domain (respectively, domain of subdifferentiability) is continuous if and only if its subdifferential is strongly cyclically monotone (respectively, σ-cyclically monotone).
Extrema of random algebraic polynomials with non-identically distributed normal coefficients
Authors: Farahmand K. , Grigorash A. 
Published: April 2009

AbstractAn asymptotic estimate is derived for the expected number of extrema of a polynomial whose independent normal coefficients possess non-equal non-zero mean values. A result is presented that generalizes in terms of normal processes the analytical device used for construction of similar asymptotic estimates for random polynomials with normal coefficients.
Locally full HNN extensions of inverse semigroups
Authors: Yamamura Akihiro 
Published: April 2009

AbstractWe investigate a locally full HNN extension of an inverse semigroup. A normal form theorem is obtained and applied to the word problem. We construct a tree and show that a maximal subgroup of a locally full HNN extension acts on the tree without inversion. Bass-Serre theory is employed to obtain a group presentation of the maximal subgroup as a fundamental group of a certain graph of groups associated with the D-structure of the original semigroup.