bluuebunny/crossref_metadata_2025 huggingface dataset:
On maxi-quasiprojective modules
Authors: Harada Manabu
Published: April 2009

We have defined a mini-injective module and given some structures of self mini-injective rings and certain relationships between such rings and QF-rings in [8] and [9].

In this short note we shall study the modules dual to mini-injective modules, which we call maxi-quasiprojective modules. We shall give a characterization and some structures, in terms of the above modules, of those rings whose every injective modules has the lifting property of direct decompositions modulo the Jacobian radical (see [5], [6] and [7]). Furthermore, we shall show that the above rings are closely related to QF-rings (see [8] and [9]).
Inverse semigroups with idempotents dually well-ordered
Authors: Clement A. , Pastijn F.
Published: April 2009

All inverse semigroups with idempotents dually well-ordered may be constructed inductively. The techniques involved are the constructions of ordinal sums, direct limits and Bruck-Reilly extensions.
A problem in two-dimensional integration
Authors: Henstock Ralph
Published: April 2009

If two functions of a real variable are integrable over two intervals, say oft, τ, respectively, then the product of the two functions should be integrable over the rectangular product of the two intervals oftand τ. For the Lebesgue integral, definable using non-negative functions alone, the proof is easy. For non-absolute integrals such as the Perron, Çesàro-Perron, and Marcinkiewicz-Zygmund integrals we have difficulties since the functions cannot be assumed non-negative. But the present paper gives a proof.
Objets compacts dans les topos
Authors: Dubuc Eduardo J. , Penon Jacques
Published: April 2009

It is well known that compact topological spaces are those space K for which given any point x0 in any topological space X, and a neighborhood H of the fibre -1 {x0} KXX, then there exists a neighborhood U of x0 such that -1UH. If now is an object in an arbitrary topos, in the internal logic of the topos this property means that, for any A in and B in K, we have (-1AB)=AB. We introduce this formula as a definition of compactness for objects in an arbitrary topos. Then we prove that in the gross topoi of algebraic, analytic, and differential geometry, this property characterizes exactly the complete varieties, the compact (analytic) spaces, and the compact manifolds, respectively.
On concircular transformations in Riemannian spaces
Authors: Chongshan Luo
Published: April 2009

This paper introduces a tensor that contains the Riemannian curvature tensor and the conformal curvature tensor as special examples in the Riemannian space (Mn, g), and by using this tensor we define C-semi-symmetric space. In this paper, we have the following main result: if there is a non-trivial concircular transformation between two C-semi-symmetric spaces, then both spaces are of quasi-constant curvature.
On a linear differential system of neutral type
Authors: Tsamatos P. Ch.
Published: April 2009

This paper is concerned with the neutral type differential system with derivating arguments. By decomposing the space of initial functions into classes, it is derived that, for each class, the space of corresponding solutions is of finite dimension. The case of common fixed points of the arguments is also studied.
On vector lattice-valued measures II
Authors: Panchapagesan T. V. , Palled Shivappa Veerappa
Published: April 2009

For a weakly (, )-distributive vector lattice V, it is proved that a V {}-valued Baire measure 0 on a locally compact Hausdorff space T admits uniquely regular Borel and weakly Borel extensions on T if and only if 0 is strongly regular at . Consequently, for such a vector lattice V every V-valued Baire measure on a locally compact Hausdorff space T has unique regular Borel and weakly Borel extensions. Finally some characterisations of a weakly (, )-distributive vector lattice are given in terms of the existence of regular Borel (weakly Borel) extensions of certain V {}-valued Barie measures on locally compact Hausdorff spaces.
Chinese remainder theorems and Galois modules
Authors: Ormerod Neil
Published: April 2009

This paper studies the relationship between a normal algebraic extension L of an algebraic number field K, viewed as a Galois module, and valuations of the field L. In particular, the paper seeks to establish a relationship between Galois submodules of L and certain types of Chinese Remainder Theorems.
Decomposable graphs and hypergraphs
Authors: Lauritzen S. L. , Speed T. P. , Vijayan K.
Published: April 2009

We define and investigate the notion of a decomposable hypergraph, showing that such a hypergraph always is conformal, that is, can be viewed as the class of maximal cliques of a graph. We further show that the clique hypergraph of a graph is decomposable if and only if the graph is triangulated and characterise such graphs in terms of a combinatorial identity.
Alexander polynomials of two-bridge links
Authors: Kanenobu Taizo
Published: April 2009

We provide an algorithm for calculating the Alexander polynomial of a two-bridge link by putting every two-bridge link in a special type of Conway diagram. Using this algorithm, some necessary conditions for a polynomial to be the Alexander polynomial of a two-bridge link are given, in particular, certain alternating and monotonicity conditions on the coefficients, analogous to corresponding known properties of the reduced Alexander polynomial.
Perturbation of zeros in the presence of symmetries
Authors: Dancer E. N.
Published: April 2009

We study the existence of zeros of a perturbed nonlinear operator near a zero of the unperturbed operator in the case where both operators are invariant under a symmetry group. To do this, we first correct some work of Rubinsztein on the G-homotopy groups of spheres.
On bitopological quasi-pseudometrization
Authors: Romaguera S.
Published: April 2009

In this paper we give a sufficient condition of quasi-pseudometrization for bitopological spaces. From this condition we obtain, as immediate corollaries, some known results.
Denseness of operators which attain their numerical radius
Authors: Berg I. D. , Sims Brailey
Published: April 2009

We show that a bounded linear operator on a uniformly convex space may be perturbed by a compact operator of arbitrarily small norm to yield an operator which attains its numerical radius.
Symmetrisable operators
Authors: Silberstein J. P. O.
Published: April 2009

About 14 years ago A. C. Zaanen [7] published a series of papers on compact symmetrisable linear operators in Hilbert space. Four years later I was encouraged by Dr. F. Smithies to study the spectral properties of general symmetrisable operators in Hilbert space and the resulting research formed the basis of part of a dissertation I submitted to the University of Cambridge in 1952 [4]. For various personal reasons I have not previously been able to, publish these results more widely, although I believe some of them, at least, to be of general interest.
Altitudes of a simplex in n-space
Authors: Mandan Sahib Ram
Published: April 2009

In continuation of the two previous papers (10; 11), this paper was originally written at the Indian Institute of Technology, Kharagpur and revised at the University of Sydney under the advice of Prof. T. G. Room. Although the altitudes of a general simplex S(A) in n-space (n > 2) do not concur as they do for a triangle (n = 2), yet we observe that its Monge point, M (1; 5), is an appropriate analogue of the orthocentre of a triangle such that M coincides with its orthocentre when it is orthogonal (or orthocentric). In consistency with the previous papers (10; 11; 13; 15) we shall call M as the S-point of S(A) and denote it as S as explained in § 1.2. The altitudes of S(A) are all met by the (n − 2)-spaces normal to its plane faces at their orthocentres, each parallel to of them, thus indicating the associated character of the altitudes as discussed separately in 2 other papers (12; 16). Before we introduce an orthogonal simplex and develop its properties in regard to its γ-altitudes and associated hyperspheres, we come across a number of intermediate ones of special interest. Two special types are treated here and the other two are developed in 2 other papers (13; 15).
On a nonlinear boundary value problem involving a small parameter
Authors: Erdéyi A.
Published: April 2009

In this paper we shall discuss the boundary value problem consisting of the nonlinear ordinary differential equation of the second order, and the boundary conditions.
An approximate stochastic model for phage reproduction in a bacterium
Authors: Gani J.
Published: April 2009

The stochastic birth-death process considered in this paper provides an approximate model for phage reproduction in a bacterium. In a recent paper, Hershey [1] has discussed reproduction and recombination in phage crosses, and a deterministic model for the reproductive process has been the subject of a previous note by the author [2]. A very readable account of the process is given by Sanders [3] in his recent article, “The life of viruses”.
Monogenic inverse semigroups
Authors: Preston G. B.
Published: April 2009

We give a survey of some of the realisations that have been given of monogenic inverse semigroups and discuss their relation to one another. We then analyse the representations by bijections, combined under composition, of monogenic inverse semigroups, and classify these into isomorphism types. This provides a particularly easy way of classifying monogenic inverse semigroups into isomorphism types. Of interest is that we find two quite distinct representations by bijections of free monogenic inverse semigroups and show that all such representations must contain one of these two representations. We call a bijection of the form ai ↦ ai+1, i = 1,2,…, r − 1, a finite link of length r, and one of the form ai ↦ ai+1, i = 1,2…, a forward link. The inverse of a forward link we call a backward link. Two bijections u: A → B and r: C → D are said to be strongly disjoint if A ∩ C, A ∩ D, B ∩ C and B ∩ D are each empty. The two distinct representations of a free monogenic inverse semigroup, that we have just referred to, are first, such that its generator is the union of a counbtable set os finite links that are pairwise storongly disjoint part of any representation of a free monogenic inverse semigroup, the remaining part not affecting the isomorphism type. Each representation of a monogenic inverse semigroup that is not free contains a strongly disjoint part, determining it to within isomorphism, that is generated by either the strongly disjoint union of a finite link and a permutation or the strongly disjoint union of a finite and a forward link.
A survey of intergration by parts for Perron integrals
Authors: Bullen P. S.
Published: April 2009

The history of the proof of the integration by parts formula for the Perron integral, and for the SCP-integral of Burkill, is discussed.
Perturbations of type I Aw*-algebras
Authors: Khoshkam Mahmood
Published: April 2009

The distance between two operator algebras acting on a Hilbert space H is defined to be the Hausdorff distance between their unit balls. We investigate the structural similarities between two close AW*-algebras A and B acting on a Hilbert space H. In particular, we prove that if A is of type I and separable, then A and B are *-isomorphic.
On the conjugacy classes in the unitary, symplectic and orthogonal groups
Authors: Wall G. E.
Published: April 2009

This paper is concerned with two mani problems:

(a) the determination of the conjugacy classes in the finite-dimensional unitary, symplectic and orthogonal groups over division rings or fields;

(b) the determination of the equivalence classes of non-degenerate sesquilinear forms on finite-dimensional vector spaces.
The elastodynamics of moving loads, Part 1: The field of a semi-infinite line load moving on the surface of an elastic solid with constant supersonic velocity
Authors: Papadopoulos Michael
Published: April 2009

When a semi-infinite line load moves lengthways, at supersonic velocity, on the plane surface of an elastic solid, the resulting velocity field is conical. There are two characteristic cones, one associated with dilatation effects and the other with shear effects. The propagation process is more complicated than the well-known case of conical flow in supersonic aerodynamics not only because of the presence of two cones of discontinuity but also because the presence of a free surface implies interaction between shear and dilatation effects. It is the interaction process at the free surface which is examined in detail in this paper.

The results of this fundamental problem may be extended by the process of superposition to more general steadily moving loads. In particular by differentiating with respect to time, the potential of a steadily moving point load is obtained explicitly.
Two non-linear birth and death processes
Authors: Bather J. A.
Published: April 2009

The random processes discussed here may be specified in the following way. A fixed population of N members is spilt into two distinct classes. Individuals move about randomly between the classes, and we are interested in the size of each class at any time, rather than in the behaviour of particular individuals. Let i(t) and N —i(t) be the numbers present in the repective classes at the time t. It is assumed that the process {i(t), t ≧ 0} is Markovian, and that transitions between the states j = 0, 1, … N, occur according to the conditional probabilities; and.
The structure of cyclic paired-comparison designs
Authors: David H. A.
Published: April 2009

When n objects are to be compared in pairs, a complete experiment requires N= comparisons. There are frequent occasions when it si desirable to make only a fraction F of the possible comparison, either because N is large or because even an individual comparison is laborious. The problem of what constitutes a satisfactory subset of the comparisons has been considered by Kendall [5[ who lays down the following two minimum requirements: (a) every object should appear equally often; (b) the design should be ‘connected‘ so that it is impossible to split the objects into two sets with no comparison made between objects in one set and objects in the other.
Serial dependence of a Markov process
Authors: Craven B. D.
Published: April 2009

Consider a Markov process defined in discrete time t = 1, 2, 3, hellip on a state space S. The state of the Process at time time t will be specifies by a random varable Vt, taking values in S. This paper presents some results concerning the behaviour of the saquence V1, V2, V3hellip, considered as a time series. In general, S will be assumed to be a Borel subset of an h-dimensional Euclideam space, where h is finite. The results apply, in particular, to a continuous state space, taking S to be an interval of the realine, or to discrete process having finitely or enumerably many states. Certain results, which are indicated in what follows, apply also to more general (infinite-dimensional) state spaces.
On digital distribution in some integer sequences
Authors: Craven B. D.
Published: April 2009

Although the harmonic series diverges, there is a sense in which it “nearly converges”. Let N denote the set of all positive integers, and S a subset of N. Then there are various sequences S for which converges, but for which the “omitted sequence” N–S is, in intuitive sense, sparse, compared with N. For example, Apostol [1] (page 384) quotes, without proof the case where S is the set of all Positive integers whose decimal representation does not invlove the digit zero (e.g. 7∈S but 101 ∉ S); then (1) converges, with T < 90.
On the completeness of Galois theories
Authors: Venkataraman M. , Soundararajan T.
Published: April 2009

Let E be a given field and G some (not necessarily the total) group of automorphisms of E. We introduce a topology in G by saying that a net of elements Tα in G converges to T in G if for each x∈E, Tα(x) coincides with Tα(x) ultimately. We shall call this the Krull topology on G.
An example of a function with non-analytic iterates
Authors: Lewin M.
Published: April 2009

Let Ω be the set of the analytic functions F(z), regular in some neighbourhood of the origin with the expansion There may exist a function F(s, z) arndytic in s and satisfying the following conditions (s and s′ are any complex numbers): and the ƒ k(s) are polynomials in s.
Remark on the defining relation of the σ-symbols
Authors: Buchdahl H. A.
Published: April 2009

It is shown algebraically that the full defining relation for the σκ(img)ν is effectively contained in its symmetric part.
Approximation of functions by means of Lipschitz functions
Authors: Michael J. H.
Published: April 2009

Let Q denote the closed unit cube in Rn. The elementary area A(f) of a Lipschitz function f on Q is given by the formula.
Weak convergence of vector-valued series and integrals
Authors: Edwards R. E.
Published: April 2009

Throughout this paper E, F and G denote separated locally convex spaces, F C G, the injection i: F → G being continuous (i.e. the topology on F is finer than that induced on it by the topology on G). E′, F′ and G′ denote the respective duals of E, F and G. i′ is the adjoint map of G′ into F', which is defined by restricting linear forms on G to F C G.
Linear groups analogous to permutation groups
Authors: Wong W. J.
Published: April 2009

If G is a finite linear group of degree n, that is, a finite group of automorphisms of an n-dimensional complex vector space (or, equivalently, a finite group of non-singular matrices of order n with complex coefficients), I shall say that G is a quasi-permutation group if the trace of every element of G is a non-negative rational integer. The reason for this terminology is that, if G is a permutation group of degree n, its elements, considered as acting on the elements of a basis of an n-dimensional complex vector space V, induce automorphisms of V forming a group isomorphic to G. The trace of the automorphism corresponding to an element x of G is equal to the number of letters left fixed by x, and so is a non-negative integer. Thus, a permutation group of degree n has a representation as a quasi-permutation group of degree n.
The single server queueing system with Non-recurrent input-process and Erlang service time
Authors: Finch P. D.
Published: April 2009

We consider a single server queueing system in which customers arrive at the instants t0, t1, …, tm, …. We write τm = tm+1 − tm, m ≧ 0. There is a single server with distribution of service times B(x) given by where k is an integer not less than unity.
A coincidence problem in telephone traffic with non-recurrent arrival process
Authors: Finch P. D.
Published: April 2009

We consider the following problem. Calls arrive at a telephone exchange at the instants t0, t1, … tm …. The telephone exchange contains a denumerable infinity of channels. The holding times of calls are non-negative random variables distributed independently of the times at which calls arrive, independently of which channel a call engages and independently of each other with a common distribution function B(x). Takacs [3Τm = tm+1 − tm, m ≧ are identically and independently distributed non-negative random variables with common distribution function, A (x). Finch [1] has studied the transient behaviour in the case of a recurrent arrival process and exponential holding time, that is when the common distribution of holding time is given by In this paper we make no assumption about the arrival process {tm}. The underlying principle of this paper is the same as that of Finch [2]. We consider the instants of arrival t0, t1,…, tm,… as given and determine various probabilities of interest conditionally as functions of the inter-arrival intervals Τ1,…, Τm,… When the arrival process is a stochastic process we can then determine the relevant unconditional probabilities by integration.
The transient behaviour of a single server queue with batch arrivals
Authors: Brockwell P. J.
Published: April 2009

A queue at which arrivals occur randomly in batches of fixed size r and for which the service times are independent negative exponential variates is considered. Expressions are obtained for the moments of the transient waiting time distribution and the distribution of the number of customers in the system just before the nth batch arrives. The distribution of the number of customers served in a busy period is also determined.
A new class of symmetric weighing matrices
Authors: Kharaghani H.
Published: April 2009

If there is a W (n, p), then there is a symmetric W (n2, p2).
On the commutants modulo Cp of A2 and A3
Authors: Kittaneh Fuad
Published: April 2009

We prove the following statements about bounded linear operators on a complex separable infinite dimensional Hilbert space. (1) Let A and B* be subnormal operators. If A2X = XB2 and A3X = XB3 for some operator X, then AX = XB. (2) Let A and B* be subnormal operators. If A2X – XB2 ∈ Cp and A3X – XB3 ∈ Cp for some operator X, then AX − XB ∈ C8p. (3) Let T be an operator such that 1 − T*T ∈ Cp for some p ≥1. If T2X − XT2 ∈ Cp and T3X – XT3 ∈ Cp for some operator X, then TX − XT ∈ Cp. (4) Let T be a semi-Fredholm operator with ind T < 0. If T2X − XT2 ∈ C2 and T3X − XT3 ∈ C2 for some operator X, then TX − XT ∈ C2.
A variational method for the construction of convergent iterative sequences
Authors: Rubinstein Zalman
Published: April 2009

Convergent iterative sequences are constructed for the polynomials fm = z + zm, m ≧ 2, with initial point the lemniscate {z: |fm (z)| ≦1}. In the particular case m = 2 convergent iterative sequences are constructed also for f-1m, (z) with an arbitrary initial point. The method is based on a certain variational principle which allows reducing the problem to the well known situation of an analytic function mapping a simply connected domain into a proper subset of itself and possessing a fixed point in the domain.
Cumulants and partition lattices IV: a.s. convergence of generalised k-statistics
Authors: Speed T. P.
Published: April 2009

Generalised k-statistics associated with multi-indexed arrays of random variables satisfying a generalised form of exchangeability are studied. By showing that they form multi-indexed reversed martingales and that the associated family of σ-fields possesses certain conditional independence properties, conditions for the a.s. convergence of generalised k-statistics are obtained. When the arrays of random variables are sums of independent arrays of independent effects, as is the case with the standard random effects anova models, the limits are identified as the associated generalixed cumulants.
Classical isol incomparability and ∞ · on manifold RET's
Authors: Harkleroad Leon
Published: April 2009

An infinite collection of indecomposable isols such that no isol is comparable to certain infinitary combinations of the others is constructed, extending a result of Dekker and Myhill. This collection is then used to investigate differences between the arithmetic of classical RET's and that of RET's on recursive manifolds, a difference relevant to the manifold equivalent of the Schröder-Bernstein Theorem.
On a representation of continuous Volterra right inverses to the derivative in the spaces of infinitely differentiable functions
Authors: Przeworska-Rolewicz Danuta , Rolewicz Stefan
Published: April 2009

Every continuous Volterra right inverse to the derivative in the space of complex-valued infinitely differentiable functions has the form of an integral.
CLT groups and wreath products
Authors: Brandl Rolf
Published: April 2009

In this paper the question is considered of when the wreath product of a nilpotent group with a CLT groupGis a CLT group. It is shown that if the field withPrelements is a splitting field of a HallP1–subgroup ofG, thenPwrGis a CLT group for allp–groupsPwith |P/P1|≥pr. Moreover, the class of all groupsGhaving the property thatNwrGis a CLT group for every nilpotent groupNis shown to be quite large. For exmple, every group of odd order can be embedded as a subgroup of a group belonging to this class.
The Finsler geometry of groups of isometries of Hilbert Space
Authors: Atkin C. J.
Published: April 2009

The paper deals with six groups: the unitary, orthogonal, symplectic, Fredholm unitary, special Fredholm orthogonal, and Fredholm symplectic groups of an infinite-dimensional Hilbert space. When each is furnished with the invariant Finsler structure induced by the operator-norm on the Lie algebra, it is shown that, between any two points of the group, there exists a geodesic realising this distance (often, indeed, a unique geodesic), except in the full orthogonal group, in which there are pairs of points that cannot be joined by minimising geodesics, and also pairs that cannot even be joined by minimising paths. A full description is given of each of these possibilities.
On the largest component of an odd perfect number
Authors: Cohen Graeme L.
Published: April 2009

It is shown that any odd perfect number has a component greater than 1020.
The calculation of π(N)
Authors: Lindgren H.
Published: April 2009

The aim of this paper is to dervie two formulae for π(N) that need involve only a few of the smallest primes. Here m is a small integer, the b's are integers that will be found later, and Pij…k denotes the number of products figi… ≧ N, in which f, g,?…,h are unequal integers greater than 1 and prime to the first m primes. The suffixes run through all partitions of all integers.
Hilbert spaces of generalized functions extending L2, (II)
Authors: Miller J. B.
Published: April 2009

The present note continues the discussion, begun in the first paper with the above title, of classes of spaces H which are extensions of L2 (0, ∞) and whose elements, which we call ‘sequence-functions’, exhibit some of the properties of distributions. The previous paper defined the spaces, and described how they can be used to extend the domain of definition of Waston transforms. Further related applications to transform theory are described in [2] and [3]. In this paper I pursue the analogy between these sequence- functions and other types of generalized functions further by discussing their local behaviour, the existence of ordinary and convolution-type products, and of derivatives and integrals.
Monotone functions mapping the set of rational numbers on itself
Authors: Neumann B. H. , Rado R.
Published: April 2009

The functions f defined by or by for c rational and less than + 1 map the set of rational numbers between 0 and 1 one-to-one onto itself; and they are the only fractional linear functions with this property. Miss Tekla Taylor recently raised the question * whether these are the only differentiable functions with the stated property. In the present note we show, by two different constructions, that the answer is negative; in each case much freedom remains, which could be used to make the functions in question have various additional properties.
A perturbation approach to Bose-condensed pairs
Authors: Thompson Colin J. , Blatt John M.
Published: April 2009

A perturbation method is developed, and is used to obtain approximate expressions for the expectation values of one-particle and two particle operators in the quasi-chemical equilibrium (pair correlation) approximation to statistical mechanics, for the case of non-extreme Bose-Einstein condensation of the correlated pairs. To lowest order, the approximate results reproduce the results obtained previously for the case of extreme Bose-Einstein condensation.
Diffraction of plane elastic waves by a crack, with application to a problem of brittle fracture
Authors: Papadopoulos M.
Published: April 2009

A crack is assumed to be the union of two smooth plane surfaces of which various parts may be in contact, while the remainder will not. Such a crack in an isotropic elastic solid is an obstacle to the propagation of plane pulses of the scalar and vector velocity potential so that both reflected and diffracted fields will be set up. In spite of the non-linearity which is present because the state of the crack, and hence the conditions to be applied at the surfaces, is a function of the dependent variables, it is possible to separate incident step-function pulses into either those of a tensile or a compressive nature and the associated scattered field may then be calculated. One new feature which arises is that following the arrival of a tensile field which tends to open up the crack there is necessarily a scattered field which causes the crack to close itself with the velocity of free surface waves.
Initial value problems in water wave theory
Authors: Mackie A. G.
Published: April 2009

The work described in this paper grew out of an attempt to generalize some results obtained in an earlier paper [4] on the water entry problem of a thin wedge or cone into an incompressible fluid. The object of the generalization was to include the effect of gravity terms. In most papers on hydrodynamic impact it is considered permissible to neglect this effect since gravity terms might be expected to play a minor role in the initial stages of the motion. However, it seems desirable to investigate the effect of including gravity terms in order both to examine the later stages of the motion and to estimate to what extent their neglect is justified in the early stages. It will be seen that it is possible to develop a fairly complete solution for the normal entry of a thin symmetric body, both for two-dimensional and axially symmetric cases, on the basis of a linearized theory. The restriction to a linearized theory means that the whole field of analysis associated with the theory of surface waves of small amplitude becomes available. Most of the problems considered in this paper are initial value problems in which the whole fluid is at rest at t = 0.
A limit theorem for Markov chains with continuous state space
Authors: Finch P. D.
Published: April 2009

Let R denote the set of real numbers, B the σ-field of all Borel subsets of R. A homogeneous Markov Chain with state space a Borel subset Ω of R is a sequence {an}, n≧ 0, of random variables, taking values in Ω, with one-step transition probabilities P(1) (ξ, A) defined by for each choice of ξ, ξ0, …, ξn−1 in ω and all Borel subsets A of ω The fact that the right-hand side of (1.1) does not depend on the ξi, 0 ≧ i > n, is of course the Markovian property, the non-dependence on n is the homogeneity of the chain.
On the strength of packed spheres
Authors: Parkin A. K.
Published: April 2009

The mechanics of a system of packed spheres has relevance to several physical disciplines. A particular case has been a recent trend among engineers to use a close-packed sphere model to aid research into the strength of cohesionless granular masses, such as sand.
Three proofs of Minkowski's second inequality in the geometry of numbers
Authors: Bambah R. P. , Woods Alan , Zassenhaus Hans
Published: April 2009

Let K be a bounded, open convex set in euclidean n-space Rn, symmetric in the origin 0. Further let L be a lattice in Rn containing 0 and put extended over all positive real numbers ui for which uiK contains i linearly independent points of L. Denote the Jordan content of K by V(K) and the determinant of L by d(L). Minkowski's second inequality in the geometry of numbers states that Minkowski's original proof has been simplified by Weyl [6] and Cassels [7] and a different proof hasbeen given by Davenport [1].
A moment problem
Authors: Takács Lajos
Published: April 2009

Let ν be a discrete random variable taking on nonnegative integer values and set P{ν = κ} = Pk, κ = 0, 1, hellip. Suppose that the binomial moments are finite. Frequently the problem arises under what conditions the probabilities Pk, k = 0, 1,…, can be determined uniquely by the sequence of moments Br, r = 0, 1,…, and how it can be done.
A note on pre-interior operators
Authors: Liu Teng-Sun
Published: April 2009

Let X be an non-empty set and denote by PX the set algebra consisting of all sunsets of X. An operator i: PX → PX is said to be Pre-interior if (i) iX = X; (ii) i(A∩B) = iA ∩ iB for all A, B in PX.
A bound for the class of certain nilpotent groups
Authors: Gupta Chander Kanta
Published: April 2009

The groups whose 2-generator subgroups are all nilpotent of class at most 2 are nilpotent of class at most 3 (see Levi [6]). Heineken [3] generalized Levi's result by proving that for n ≧ 3, if the n-generator subgroups of a group are all nilpotent of class at most n, then the group itself is nilpotent of class at most n. Other related problems have been considered by Bruck [1].
Basic representations of some affine Lie algebras and generalized Euler identities
Authors: Misra Kailash C.
Published: April 2009

We consider certain affine Kac-Moody Lie algebras. We give a Lie theoretic interpretation of the generalized Euler identities by showing that they are associated with certain filtrations of the basic representations of these algebras. In the case when the algebras have prime rank, we also give algebraic proofs of the corresponding identities.
Peripheral acyclicity in 3-manifolds
Authors: Repovš Dušan
Published: April 2009

We study weak and strong peripheral 1-acyclicity, a homology version of D. R. McMillan, Jr.'s weak cellularity criterion and cellularity criterion, for embeddings of compacta in 3-manifolds. In contrast with the two cellularity criteria we prove that the two peripheral acyclicities are equivalent and moreover, for compacta of dimension at most 1, independent of the embedding. We also give some results concerning regular neighborhoods of compact polyhedra in 3-manifolds.
Endomorphism rings of Butler groups
Authors: Arnold D. M. , Vinsonhaler C. I.
Published: April 2009

This note is devoted to the question of deciding whether or not a subring of a finite-dimensional algebra over the rationals, with additive group a Butler group, is the endomorphism ring of a Butler group (a Butler group is a pure subgroup of a finite direct sum of rank-1 torsion-free abelian groups). A complete answer is given for subrings of division algebras. Several applications are included.
Sequential binary arrays and circulant matrices
Authors: Praeger Cheryl E. , Nilrat Chaufah K.
Published: April 2009

A periodic binary array on the sequare grid is said to be sequential if and only if each row and each column of the array contains a given periodic binary sequence or some cyclic shift or reversal of this sequence. Such arrays are of interest in connection with experimental layouts. This paper extends previous results by characterizing sequential arrays on sequences of the type (1,…,1,0,…,0) and solving the problem of equivalence of such arrays (including a computation of the number of equivalence classes).
A note on uniform ordered spaces
Authors: Künzi Hans-Peter A.
Published: April 2009

We characterize the generalized ordered topological spaces X for which the uniformity (X) is convex. Moreover, we show that a uniform ordered space for which every compatible convex uniformity is totally bounded, need not be pseudocompact.
Lipschitz and differentiable dependence of solutions on a parameter in a scalarization method
Authors: Sterna-Karwat Alicia
Published: April 2009

This paper is concerned with a vector optimization problem set in a normed space where optimality is defined through a convex cone. The vector problem can be solved using a parametrized scalar problem. Under some convexity assumptions, it is shown that dependence of optimal solutions on the parameter is Lipschitz continuous. Hence differentiable dependence on the solutions on the parameter is derived.
Incomplete self-orthogonal latin squares
Authors: Heinrich Katherine , Zhu L.
Published: April 2009

We show that for all n ≥ 3k + 1, n ≠ 6, there exists an incomplete self-orthogonal latin square of order n with an empty order k subarray, called an ISOLS(n;k), except perhaps when (n;k) ∈ {(6m + i;2m):i = 2, 6}.
Generalizations of F. E. Browder's sharpened form of the schauder fixed point theorem
Authors: Tan Kok-Keong
Published: April 2009

Let E be a Hausdorff topological vector space, let K be a nonempty compact convex subset of E and let f, g: K → 2E be upper semicontinuous such that for each x ∈ K, f(x) and g(x) are nonempty compact convex. Let Ω ⊂ 2E be convex and contain all sets of the form x − f(x), y − x + g(x) − f(x), for x, y ∈ K. Suppose p: K × Ω →, R satisfies: (i) for each (x, A) ∈ K × Ω and for ε > 0, there exist a neighborhood U of x in K and an open subset set G in E with A ⊂ G such that for all (y, B) ∈ K ×Ω with y ∈ U and B ⊂ G, | p(y, B) - p(x, A)| < ε, and (ii) for each fixed X ∈ K, p(x, ·) is a convex function on Ω. If p(x, x − f(x)) ≤ p(x, g(x) − f(x)) for all x ∈ K, and if, for each x ∈ K with f(x) ∩ g(x) = ø, there exists y ∈ K with p(x, y − x + g(x) − f(x)) < p(x, x − f(x)), then there exists an x0 ∈ K such that f(x0) ∩ g(x0) ≠ ø. Another coincidence theorem on a nonempty compact convex subset of a Hausdorff locally convex topological vector space is also given.
Well-bounded operators of type (B) in a class of Banach spaces
Authors: Ricker Werner
Published: April 2009

It is shown that in a Grothendieck space with the Dunford-Pettis property, the class of well-bounded operators of type (B) coincides with the class of scalar-type spectral operators with real spectrum. It turns out that in such Banach spaces, analogues of the classical theorems of Hille-Sz. Nagy and Stone concerned with the integral representation of C0-semigroups of normal operators and strongly continuous unitary groups in Hilbert spaces, respectively, are of a very special nature.
On generating functions for classical polynomials
Authors: Shanker O.
Published: April 2009

Recently Brown [1] gave two new classes of generating functions which include the generating functions for the polynomials of Gegenbauer, Jacobi and Laguerre. The aim of the paper is to give a new class of generating functions which includes both sets of generating functions given by Brown and provides a new class of generating functions for the polynomials of Gegenbauer, Jacobi and Laguerre.
On sequences generic in the sense of Prikry
Authors: Mathias A. R. D.
Published: April 2009

I establish here a criterion for a sequence of ordinals to be generic over a transitive model of ZFC with respect to a notation of forcing first considered by Prikry in his Doctoral dissertation [2]. In Section 0 I review some notation, in Section 1 I list some facts about measurable cardinals, and in Section 2, after giving Prikry's result, I state and prove mine.
On central primitive idempotent measures
Authors: Choy Stephen T. L.
Published: April 2009

Let S be a compact semitopological semigroup and let P(S) be the convolution semigroup of probability measures on S. An idempotent measure μ in P(S) is defined to be primitive if and only idempotent measures in μP(S)μ are μ and the zero element m of P(S). In a previous paper [2] we give some characterization of primitive idempotent measures on S. Let Π(P(S)) be the set of primitive idempotents in P(S) and let Πc be the set of central primitive idempotents in P(S). It is shown in [1] that Π(P(S)) is neither an ideal nor even a subsemigroup of P(S) in general. The purpose of this paper is to investigate the structure of Πc.
Wallman compactifications and Wallman realcompactifications
Authors: Gagrat M. S. , Naimpally S. A.
Published: April 2009

In 1964 Frink [8] generalized Wallman's method [17] of compactification and asked the question: “Is every Hausdorff compactification of a Tychonoff space a Wallman compactification?”. This problem, which is as yet unsolved, has led to the discovery of a number of necessary and/or sufficient conditions for a Hausdorff compactification to be Wallman; (see Alò and Shapiro [2], [3], Banasĉhewski [6], Njåstad [13] and Steiner [15]). Recently Alò and Shapiro [4], [5] have generalized the Wallman procedure to discuss what they call Z*-realcompact spaces and Z*-realcompactification n(Z) corresponding to a countably productive (c.p.) normal base Z on X. Some further work has been done by Steiner and Steiner [14].
The divisor problem for (k, r) — integers
Authors: Subbarao M. V. , Suryanarayana D.
Published: April 2009

Let k and r be fixed integers such that 1 < r < k. It is well-known that a positive integer is called r-free if it is not divisible by the r-th power of any integer > 1. We call a positive integer n, a (k, r)-integer, if n is of the form n = a kb, where a is a positive integer and b is a r-free integer. In the limiting case, when k becomes infinite, a (k, r)-integer becomes a r-free integer and so one might consider the (k, i) integers as generalized r-free integers.
Homomorphisms and congruences on ωα-bisimple semigroups
Authors: Hogan J. W.
Published: April 2009

LetSbe a bisimple semigroup, letEsdenote the set of idempotents ofS, and let ≦ denote the natural partial order relation onEs. Let ≤ * denote the inverse of ≦. The idempotents ofSare said to be well-ordered if (Es, ≦ *) is a well-ordered set.
Minimal presentations for groups of order 2n, n ≤ 6
Authors: Saga T. W. , Wamsley J. W.
Published: April 2009

Let G be a finite 2-group having a minimal generating set {x1, …, xr} so that r = d (G) is an invariant of G. Suppose further that G has a presentation then.
Stable trees
Authors: Holton D. A.
Published: April 2009

Abstract: We show that a tree is stable if and only if its automorphism group contains a transposition. The method is constructive and so enables a stabilising sequence to be found.
The kernel of integral cup product
Authors: Hillman Jonathan A. , Rubinstein J. H.
Published: April 2009

We compute the kernel of cup product of 1-dimensional cohomology classes for a group G acting trivially on Z or F2, by means of the naturality of cup product and the 5-term exact sequence of low degree of a suitable LHS spectral sequence. We determine thereby when cup product is injective, and when it is null.
Proper efficiency and duality for vector valued optimization problems
Authors: Weir T. , Mond B.
Published: April 2009

The duality results of Wolfe for scalar convex programming problems and some of the more recent duality results for scalar nonconvex programming problems are extended to vector valued programs. Weak duality is established using a ‘Pareto’ type relation between the primal and dual objective functions.
Extension of Riesz homomorphisms. III
Authors: Buskes Gerard
Published: April 2009

In this paper we prove an analogue of the separable version of Nachbin's characterization of injective Banach spaces in the setting of Banach lattices. The mappings involved are continuous Riesz homomorphisms defined on ideals of separable Banach lattices which can be extended to Riesz homomorphisms on the whole Banach lattice. We discuss applications to simultaneous extension operators and to extension of continuous mappings between certain topological spaces.
Finite semigroups with commuting idempotents
Authors: Ash C. J. , Hall T. E.
Published: April 2009

We show that every such semigroup is a homomorphic image of a subsemigroup of some finite inverse semigroup. This shows that the pseudovariety generated by the finite inverse semigroups consists of exactly the finite semigroups with commuting idempotents.
A Construction for Fitting-Schunck classes
Authors: Cossey John , Ormerod Elizabeth A. , Lausch H.
Published: April 2009

A method for constructing Fitting-Schunck classes is given: the method is an adaptation of one given by C. L. Kanes for constructing Fitting formations, and generalizes the Fitting-Schunck class construction given by Cossey in 1981. A criterion for deciding which of the Fitting-Schunck classes so constructed are formations is given.
On the solvability of nonlinear noncompact operator equations
Authors: Tarafdar E. U. , Thompson H. B. , Vyborny R. O.
Published: April 2009

The notion of (p, k)-epi mappings is introduced. The properties of such mappings are studied and the results obtained are applied to some differential equations.
On indefinite ternary quadratic forms
Authors: Worley R. T.
Published: April 2009

In a paper [1] with the same title Barnes has shown that if Q(x, y, z) is an indefinite ternary quadratic form of determinant d ≠ 0 then there exist integers x1, y1, z1, x2,···z3 satisfying for which Furthermore, unless Q is equivalent to a multiple of or two other forms Q2, Q3 then the constant ⅔ in (1.2) can be replaced by 1/2.2. For Q1 equality is needed on at least one side of (1.2) while for Q2, Q3 the constant ⅔ can be reduced to 12/25 but no further.
On semigroups of endomorphisms of generalized Boolean rings
Authors: Smith Douglas B. , Luh Jiang
Published: April 2009

Magill in [4] first proved that two Boolean rings are isomorphic if and only if their respective endomorphism semigroups are isomorphic. His proof, however, relied on topological techniques. More recently Maxson has published a proof of the above using purely algebraic techniques [5]. In this paper, structure theorems are given which allow us to extend the above result to thepk-rings of Foster [1]. As a special case, the result is shown to apply also top-rings. An example is given to show that a further extension toJ-rings is impossible.
Matrix transformation of univalent power series
Authors: Hartmann F. W. , MacGregor T. H.
Published: April 2009

Suppose that A = [αnk], (n, k = 0, 1, 2, …), is an indinite matrix with complex entries. A transforms a complex sequence a = {an to a complex sequence {bn = b = Aa where assuming that the series in (1) converges. Each sequence a = {an is uniquely associated with a power series In this way the matrix A transforms a power series into a power series. Specifically, the power series (2) is mapped to the power series where the bn's are given by (1). We are only interested in matrices having the property that each power series analytic in Δ = {z: |z| < 1} maps to a power series analytic in Δ.
Some radical constructions for associative rings
Authors: Gardner B. J.
Published: April 2009

Dickson's construction [1] of radical and semi-simple classes for certain abelian categories is a rather straightforward procedure in comparison with the methods traditionally used in more general situations. In §2 of the present paper we use a well-known characterization of the lower radical class to obtain, via consideration of maps with accessible images, a similar “homomorphic orthogonality” characterization of radical and semi-simple classes of associative rings. By substituting certain other subring properties for accessibility, we are then able to obtain simple constructions of various types of radical classes, including those which are strict in the sense first used by Kurosh [3] for groups.
Lattice completion of the metrizable topologies
Authors: Riecke C. V.
Published: April 2009

Several classes of topological spaces which are either the infimum or supremum of a family of metrizable topologies in the lattice of topologies were given by Anderson [1]. In this paper we investigate the completion of the set of metrizable topologies in four distinct convergence structure lattices on an infinite set. We also observe the influence on these completions of the question regarding the existence of nonnormal ultrafilters which Čech [3] asserted could be neither provednor disproved using present mathematical axiom systems.
Closure operators and projections on involution posets
Authors: Rüttimann Gottfried T.
Published: April 2009

Investigations of closure operators on an involution poset T lead to a certain type of closure operators (so called c-closure operators) that are closely related to projections on T.
A Contrast between complex and real-valued Taylor series
Authors: Abian Alexander
Published: April 2009

In this paper it is shown that if c is a point of the region of convergence of an analytic function f(z) = Σ∞ncnZn then in every neighborhood of c there exists a point e such that the value f(c) of the function f(z) is attained by some truncation Σkn=0cnZn off(z) at z = e, i.e., Σkn=0cnen = Σ∞n=0cncn. Also it is shown that the above does not hold in the case of real-valued functions of a real variable.
Pseudondilpotent groups
Authors: Weigold James
Published: April 2009

The purpose of this note is to introduce some “canonical” characteristic, subgroups and to observe some of their more obvious properties.
A note on annihilator and complemented Banach aigebras
Authors: Wong Pak-Ken
Published: April 2009

The purpose of this paper is to generalize some results in a recent paper by Tomiuk and the author ([11]).