bluuebunny/crossref_metadata_2025 huggingface dataset:
Some properties of the Levitzki radical in alternative rings
Authors: Rich Michael
Published: April 2009

Two local nilpotent properties of an associative or alternative ringAcontaining an idempotent are shown. First, ifA=A11+A10+A01+A00is the Peirce decomposition ofArelative toethen ifais associative or semiprime alternative and 3-torsion free then any locally nilpotent idealBofAiigenerates a locally nilpotent ideal 〈B〉 ofA. As a consequenceL(Aii) =Aii∩L(A)for the Levitzki radicalL. Also bounds are given for the index of nilpotency of any finitely generated subring of 〈B〉. Second, ifA(x)denotes a homotope ofAthenL(A)⊆L(A(x))and, in particular, ifA(x)is an isotope ofAthenL(A)=L(A(x)).
Transcendence measures by a method of Mahler
Authors: Miller William
Published: April 2009

Suppose that f(z) is a function of one complex variable satisfying

where ρ is an integer larger than 1 and a(z) and b(z) are rational functions. We consider f evaluated at the algebraic point a and develop a transcendence measure for f(α) under suitable conditions on f and α.
On normal numbers
Authors: Pearce C. E. M. , Keane M. S.
Published: April 2009

Schmidt has shown that if r and s are positive integers and there is no positive integer power of r which is also a positive integer power of s, then there exists an uncountable set of reals which are normal to base r but not even simply normal to base s. We give a structurally simple proof of this result
Finite inverse perfect semigroups and their congruences
Authors: Hamilton Howard , Tamura Takayuki
Published: April 2009

In this paper we characterize the structure of finite inverse perfect semigroups and study congruences on those semigroups, in particular we study those semigroups that have modular lattice of congruences.
An instability theorem for a certain sixth order differential equation
Authors: Ezeilo J. O. C.
Published: April 2009

The object of the paper is to establish an instability theorem for sixth order differential equations of the form (1.1). The proof is based on the use of Krasovskii criteria.
Hall-closure and products of Fitting classes
Authors: Brison Owen J.
Published: April 2009

The Fitting class (of finite, soluble, groups), , is said to be Hall π-closed (where π is a set of primes) if whenever G is a group in and H is a Hall π-subgroup of G, then H belongs to . In this paper, we study the Hall π-closure of products of Fitting classes. Our main result is a characterisation of the Hall π-closedFitting classes of the form (where denotes the so-called smallest normal Fitting class), subject to a restriction connecting π with the characteristic of . We also characterise those Fitting classes (respectively, ) such that (respectively, ) is Hall π-closed for all Fitting classes . In each case, part of the proof uses a concrete group construction. As a bonus, one of these construction also yields a “cancellation result” for certain products of Fitting classes.
Lower bound for the number of real roots of a random algebraic polynomial
Authors: Mishra M. N. , Nayak N. N. , Pattanayak S.
Published: April 2009

Let X1, X2, …, Xn be identically distributed independent random variables belonging to the domain of attraction of the normal law, have zero means and Pr{Xr ≠ 0} > 0. Suppose a0, a1, …, an are non-zero real numbers and max and εn is such that as n → ∞, εn. If Nn be the number of real roots of the equation then for n > n0, Nn > εn log n outside an exceptional set of measure at most provided limn→∞ (kn/tn) is finite.
Essentially closed radical classes
Authors: Loi N. V.
Published: April 2009

The main goal of this paper is to describe radical classes closed under essential extensions. It turns out that such classes are precisely the homomorphically closed semisimple classes, and hence a radical class is essentially closed if and only if it is subdirectly closed. Moreover, a class is closed under homomorphic images, direct sums and essential extensions if and only if it is an essentially closed radical class. Also radical classes are investigated which are closed under Dorroh essentially extensions only, such a radical class R consists of idempotent rings provided that R does not contain the ring of integers, meanwhile all the other radicals satisfy this requirement. A description of (hereditary and) Dorroh essentially closed radicals is given in Theorem 4.
Totally umbilical submanifolds in irreducible symmetric spaces
Authors: Chen Bang-Yen , Verheyen Paul
Published: April 2009

A submanifold of a Riemannian manifold is called a totally umbilical submanifold if its first and second fundamental forms are proportional. In this paper we prove the following best possible result.
Measurability of functions of two variables
Authors: Michael J. H. , Rennie B. C.
Published: April 2009

This paper investigates the existence and equality of the double and repeated integrals of a real function on a plane set. The main result (Theorem 2) is that if a function on a plane Lebesgue measurable set is continuous in one variable and measurable in the other then it is measurable in the plane.
Mildly distributive semilattices
Authors: Hickman Robert
Published: April 2009

There is no single generalization of distributivity to semilattices. This paper investigates the class of mildly distributive semilattices, which lies between the two most commonly discussed classes in this area—weakly distributive semilattices and distributive semilattices. Particular attention is paid to describing and characterizing congruence distributive mildly distributive semilattices, in contrast to distributive semilattices, whose lattice of join partial congruences is badly behaved and which are difficult to describe.
A characteristic property of PSL2(7)
Authors: Wujie Shi
Published: April 2009

In this note we characterize PSL2(7) by conditions on the order of the group and the orders of its elements.
A note on the Levitzki radical of a near-ring
Authors: Groenewald N. J. , Potgieter P. C.
Published: April 2009

It is known that in a near-ring N the Levitzki radical L(N), that is, the sum of all locally nilpotent ideals, is the intersection of all the prime ideals P in N such that N/P has zero Levitzki radical. The purpose of this note is to prove that L(N) is the intersection of a certain class of prime ideals, called l-prime ideals. Every l-prime ideal P is such that N/P has zero Levitzki radical. We also introduce an l-semi-prime ideal and show that P is an l-semi-prime ideal if and only if N/P has zero Levitzki radical. We get another characterization of the Levitzki radical of the near-ring as the intersection of all the l-semi-prime ideals.
Cohomology and extensions of regular semigroups
Authors: Loganathan M.
Published: April 2009

Let S be a regular semigroup and A a D(S)-module. We proved in a previous paper that the set Ext(S, A) of equivalence classes of extensions of A by S admits an abelian group structure and studied its functorial properties. The main aim of this paper is to describe Ext(S, A) as a second cohomology group of certain chain complex.
Addition of an identity to an ordered Banach space
Authors: Robinson Derek W. , Yamamuro Sadayuki
Published: April 2009

Given an ordered Banach space ℬ equipped with an order-norm we construct a larger space ℬ¯ with an order-norm and order-identity such that B is isometrically order-isomorphic to a Banach subspace of B. We also discuss the extension of positive operators from ℬto ℬ¯.
The saturation phenomena for Tikhonov regularization
Authors: Groetsch C. W. , King J. T.
Published: April 2009

This paper is concerned with a characterization of the optimal order of convergence of Tikhonov regularization for first kind operator equations in terms of the “smoothness” of the data.
On p-adic F-functions
Authors: Lianxiang Wang
Published: April 2009

We introduce the class of p-adic F-functions which contains both the p-adic E-function and p-adic G-functions, as well as other functions. In this paper we obtain lower bounds for polynomials in the values at algebraic points of a class of p-adic F-functions defined over the completion of the algebraic closure of a p-adic field.
Nonexistence of universal paracompact M-spaces
Authors: Kato Akio
Published: April 2009

For a cardinal m with ω ≤ m ≤ 2≤m is embeddable in it as a closed subspace. We derive this result from the corresponding statement for metric spaces.
A generalisation of the radon-nikodym theorem
Authors: Finch P. D.
Published: April 2009

Let be a space of points x, a σ-field of subsets of a σ-finite measure on . The elements of will be called measurable sets and all the sets considered in this paper are measurable sets. A real-valued point function t(x) on will be said to be measurabl if, for each real α, the set {x: t(x)≦ α} is measurable. Let (S), S C denote the σ-field of all measurable subsets of S. A real-valued function f(·) on will be called a set function.
Monotone mappings in topological linear spaces
Authors: Yamamuro Sadayuki
Published: April 2009

Let E be a topological linear space over the real number field. Throughout of this paper, we denote by G an open subset of E, by ∂G the boundary of G and by the closure of G. The totality of all circled open neighbourhoods of the zero element denoted by U.
Self-polar double configurations in projective geometry
Authors: Room T. G.
Published: April 2009

The principal theorem to be proved in this part is: Theorem II. If in IIn a normal rational curve, ρ, and a quadric primal S are such that there is a proper simplex inscribed in ρ and self-polar with regard to S, then there exist sets of N, = (2n+1/2), chords of р every two of which are conjugate with regard to S. A set can be constructed to contain any pair of chords of р which are conjugate with regard to S.
Hilbert spaces of generalized functions extending L2, (I)
Authors: Miller John Boris
Published: April 2009

By using certain fractional integrals and derivatives it is possible to construct a continuum of Hilbert spaces within the space L2 (0, ∞); these are the spaces gλ of functions f(x) for which 1xλf(λ)(x) є L2(0, ∞), and they exhibit invariance properties under generalized Fourier transformations. They are described in (6) and (7).
The characterisation of the normal distribution
Authors: Lancaster H. O.
Published: April 2009

There are a number of well known theorems on the mutual independence of forms, either linear or quadratic, in normal variables. Some of these theorems can only hold when the system of variables is normal or degenerate and so the possibility of certain forms being independent characterises the normal distribution. The theorems on characterisation have usually been proved by consideration of the necessary properties of the characteristic function. Here we shall be considering the characteristic function of the variables but we shall make more use of cumulant theory than previous authors. To do so we have first to prove that the existence of cumulants of all orders is implied by the independence conditions. The basic theorems we use are those from general cumulant theory and the special theorems of Cramer and of Marcinkiewicz. An advantage of the methods of this paper is that it is possible to show that some of the characterisation theorems require neither of these special theorems. For example, spherical symmetry is a very strong condition and so neither theorem is required whereas both theorems are needed for the most general theorems on the independence of two linear forms. Throughout we take the class of normal distributions to include the degenerate normal, that is, the distribution of a sure variable.
One more method to construct the irreducible unitary representations of nipotent Lie groups
Authors: Astaneh A. A.
Published: April 2009

In this paper one more canonical method to construct the irreducible unitary representations of a connected, simply connected nilpotent Lie group is introduced. Although we used Kirillov' analysis to deduce this procedure, the method obtained differs from that of Kirillov's, in that one does not need to consider the codjoint representation of the group in the dual of its Lie algebra (in fact, neither does one need to consider the Lie algebra of the group, provided one knows certain connected subgroups and their characters). The method also differs from that of Mackey's as one only needs to induce characters to obtain all irreducible representations of the group.
On dominated convergence
Authors: Rennie Basil C.
Published: April 2009

The great theorem on convergence of integrals is due in its usual form to Lebesgue [2] though its origins go back to Arzela [1]. It says that the integral of the limit of a sequence of functions is the limit of the integrals if the sequence is dominated by an integrable function. This paper investigates the converse problem — if we know that we may take limits under the integral sign, then what can we say about the convergence? The answer is found for functions of a real variable, but it is easily extended to any space with a countably additive measure. Finally the result is illustrated by an application to Fourier series.
Note on the harmonic oscillator in general relativity
Authors: Taylor N. W.
Published: April 2009

The theory of relativity shows that the times measured by two observers will in general be different if they are in relative motion, so that their respective times between any two coincidences will differ. Bergmann [1] has investigated the problem of a particle moving in a small simple harmonic motion in a static gravitational field, and has found that the time difference for this particle and an observer at rest becomes zero whenever the particle passes through the centre and limits of its swing. This problem will now be dealt with in a different manner, using Schwarzschild's interior solution of the gravitational equations. The exterior solution for a point mass is not suitable in the present case, due to the singularity of the field at a point in the path of the particle.
Spans of translates in Lp(G)
Authors: Edwards R. E.
Published: April 2009

Throughout this paper, G denotes a Hausdorff locally compact Abelian group, X its character group, and Lp(G) (1 ≦ p ≦ ∞) the usual Lebesgue space formed relative to the Haar measure on G. If f ∈ Lp(G), we denote by Tp[f] the closure (or weak closure, if p = ∞) in Lp(G) of the set linear combinations of translates of f.
On sequences of integrable functions
Authors: Rennie Basil C.
Published: April 2009

Let f1(x), f2(x), … be a sequence of functions belonging to the real or complex Banach space L, (see S. Banach: [1] (The results can be generalised to functions on any space that is the union of countably many sets of finite measure). We are concerned with various properties that such a sequence may have, and in particular with the more important kinds of convergence (strong, weak and pointwise). This article shows what relations connect the various properties considered; for instance that for strong convergence (i.e. ║fn — f║ → 0) it is necessary and sufficient firstly that the sequence should converge weakly (i.e. if g is bounded and measurable then f(fn(x) — f(x))g(x)dx → 0) and secondly that any sub-sequence should contain a sub-sub-sequence converging p.p. to f(x).
Isomorphic subgraphs having minimal intersections
Authors: Mullin R. C. , Roy B. K. , Schellenberg P. J.
Published: April 2009

Given a finite graph H and G, a subgraph of it, we define σ (G, H) to be the largest integer such that every pair of subgraphs of H, both isomorphic to G, has at least σ(G, H) edges in common; furthermore, R(G, H) is defined to be the maximum number of subgraphs of H, all isomorphic to G, such that any two of them have σ(G, H) edges common between them. We are interested in the values of σ(G, H) and R(G, H) for general H and G. A number of combinatorial problems can be considered as special cases of this question; for example, the classical set-packing problem is equivalent to evaluating R (G, H) where G is a complete subgraph of the complete graph H and σ(G, H) = 0, and the decomposition of H into subgraphs isomorphic to G is equivalent to showing that σ(G, H) = 0 and R(G, H) = ε(H)/ε(G) where ε(H), ε(G) are the number of edges in H, G respectively.

A result of S. M. Johnson (1962) gives an upper bound for R(G, H) in terms of σ(G, H). As a corollary of Johnson's result, we obtain the upper bound of McCarthy and van Rees (1977) for the Cordes problem. The remainder of the paper is a study of σ (G, H) and R(G, H) for special classes of graphs; in particular, H is a complete graph and G is, in most instances, a union of disjoint complete subgraphs.
2-Groups of almost maximal class: corrigendum
Authors: James Rodney
Published: April 2009

On page 354 of James (1975) (in the proof of Theorem 5.3(b)) there appear the following two sentences:

‘When n≥7, replacewe may suppose δ=0.’

Unfortunately, the second sentence does not follow from the first. In fact, the first sentence also forces us to replace remains unaltered. Thus the case δ=1 is omitted in the paper.
A note on linear forms in a class of E-functions and G-functions
Authors: Guangshan Xu
Published: April 2009

This note establishes estimates for lower bounds of linear forms at algebraic points of E-functions and G-functions defined over a general algebraic number field.
On transitive permutation groups with a subgroup satisfying a certain conjugacy condition
Authors: Praeger Cheryl E.
Published: April 2009

Let G be transitive permutation group of degree n and let K be a nontrivial pronormal subgroup of G (that is, for all g in G, K and Kg are conjugate in (K, Kg)). It is shown that K can fix at most ½(n – 1) points. Moreover if K fixes exactly ½(n – 1) points then G is either An or Sn, or GL(d, 2) in its natural representation where n = 2d-1 ≥ 7. Connections with a result of Michael O'Nan are dicussed, and an application to the Sylow subgroups of a one point stabilizer is given.
A general measure decomposition theorem by means of the generalized wallman remainder
Authors: Bachman George , Stratigos Panagiotis D.
Published: April 2009

Let ℒ be a lattice of subsets of a setX. LetMR(ℒ) denote the set of all ℒ-regular (finitely additive) measures on the algebra generated by ℒ. Under the assumption that ℒ is disjunctive, in the first part of the paper, criteria are obtained for the σ-smoothness, τ-smoothness, and tightness of elements ofMR(ℒ) in terms of the general Wallman remander. in the second part of the paper, various applications are given, and, in particular, extensions and refinements of the Yoside-Hewitt Decom position Theorem are obtained.
Expectation values of operators in the quasi-chemical equilibrium theory part II
Authors: Blatt John M.
Published: April 2009

Expectation values of one-particle and two-particle operators are evaluated in the quasi-chemical equilibrium (pair correlation) approximation to statistical mechanics. Earlier work was restricted to the case of extreme Bose-Einstein condensation of the correlated pairs; the new formulas are not so restricted, but are correspondingly more complicated to evaluate practically. However, a simple result can be obtained for the expectation value of the number of particles.
Relatively central operators on Archimedean vector lattices II
Authors: McPolin P. T. N. , Wickstead A. W.
Published: April 2009

We continue the study of operators from an Archimedean vector lattice E into a cofinal sublattice H which have the property that there is λ > 0 such that if x ∈ E, h ∈ H and |x|≤|h|, then |Tx| ≤ λ|h|. The collection Z(E|H) of all of those operators forms an algebra under composition. We investigate the relationship between the properties of having an identity, being Abelin and being semi-simple for such-algebras, culminating in a proof that they are equivalent if H is Dedekind complete. We also study various for such an operator T, showing that, apart from 0, its spectrum relative to Z(E|H) is the same as that of T|H relative to Z(H) and that of T relative to ℒ(E) (Provided E is a Banach lattice and H is closed).
Free products of topological groups with a closed subgroup amalgamated
Authors: Nickolas Peter
Published: April 2009

It is shown that if {Gn: n = 1, 2,…} is a countable family of Hausdorff kω-topological groups with a common closed subgroup A, then the topological amalgamated free product *AGn exists and is a Hausdorff kω-topological group with each Gn as a closed subgroup. A consequence is the theorem of La Martin that epimorphisms in the category of kω-topological groups have dense image.
On supplements in finite groups
Authors: Kochendörffer R.
Published: April 2009

Let G be a finite group. If N denotes a normal subgroup of G, a subgroup S of G is called a supplement of N if we have G = SN. For every normal subgroup of G there is always the trivial supplement S = G. The existence of a non-trivial supplement is important for the extension theory, i.e., for the description of G by means of N and the factor group G/N. Generally, a supplement S is the more useful the smaller the intersection S ∩ N. If we have even S ∩ N = 1, then S is called a complement for N in G. In this case G is a splitting extension of N by S.
A note on a method of Milne-Thomson
Authors: Buchwald V. T.
Published: April 2009

Milne-Thomson has used the method of analytic continuation to solve boundary value problems of the annulus in plane elastostatics. However, his use of Cauchy integrals is incorrect, and it is shown in this note that the solution is obtained in terms of Laurent Series expansions. The solution is equivalent to that of Muskhelishvili, but is simpler to use in some applications.

A similar approach is used to solve the boundary value problem of the infinite strip, the solution being given in terms of functions of a complex variable expressed as Fourier integrals.
The convergence of Rayleigh-Ritz approximations in hydrodynamics
Authors: Lush P. E.
Published: April 2009

It is known that various cases of the steady isentropic irrotational motion of a compressible fluid are expressible as variational principle [1], [5]. in particular, the aerofoil problem i.e. the case of plane flow in which a uniform stream is locally deflected, without circulation, by a bounded obstacle, can be expressed in such a form. Thus we make stationary where the region R is that bounded internally by the obstacle (C0) and externally by a circle (CR) of radius R. In this expression φ∞ is the velocity potential for a uniform stream, and φ0 is the velocity potential for the corresponding incompressible flow.
On fourier transforms of radial functions
Authors: Griffith James L.
Published: April 2009

The Fourier transformF(y) of a functionf(t) inL1(Ek) whereEkis thek-dimensional cartesian space will be defined by.
Boolean powers of simple groups
Authors: Neumann B. H. , Yamamuro Sadayuki
Published: April 2009

We prove that factor groups of cartesian powers of finite non-abelian simple groups cannot be countably infinite. Thisis not our main result, but it had been our original aim. The proof is based on a similar fact concerning σ-complete Boolean algebras, and on a representation of certain subcartesian powers of a group in its group ring over a Boolean ring. This representation, to which we give the name “Boolean power”, will be our central theme, and we begin with it.
Topological wreath products
Authors: Lakshmi A.
Published: April 2009

The object of this note is to show that under suitable restrictions some results on the wreath product of groups can be carried over to topological groups. We prove in particular the following analogue of the well-known theorem of Krasner and Kaloujnine (see for example [2] Theorem 3.5): Theorem. Let A and B be two locally compact topological groups, and let (C, ε) be an extension of A by B. If there exists a continuous left inverseof ε, that is to say a continuous mapping τ: B → C such that re is the identity on B, then there exists a continuous monomorphism of C into the topological standard wreath product of A by B.
The lifting two-dimensional aerofoil between slotted walls
Authors: Low A. H.
Published: April 2009

A mathematical theory is developed which enables the wind-tunnel corrections to the lift and moment forces acting on an aerofoil in subsonic two-dimensional flow to be calculated. The usual “averaged” boundary condition for slotted walls is assumed and the corrections obtained by successive approximation from the open-jet tunnel.
The transient behaviour of the queueing system Gi/M/1
Authors: Brockwell P. J.
Published: April 2009

We consider a single server queue for which the interarrival times are identically and independently distributed with distribution function A(x) and whose service times are distributed independently of each other and of the interarrival times with distribution function B(x) = 1 − e−x, x ≧ 0. We suppose that the system starts from emptiness and use the results of P. D. Finch [2] to derive an explicit expression for qnj, the probability that the (n + 1)th arrival finds more than j customers in the system. The special cases M/M/1 and D/M/1 are considerend and it is shown in the general case that qnj is a partial sum of the usual Lagrange series for the limiting probability .
Uniform estimates for families of singular integrals and double Fourier series
Authors: Prestini Elena
Published: April 2009

It is an open problem to establish whether or not the partial sums operator SNN2f(x, y) of the Fourier series of f ∈ Lp, 1 < p < 2, converges to the function almost everywhere as N → ∞. The purpose of this paper is to identify the operator that, in this problem of a.e. convergence of Fourier series, plays the central role that the maximal Hilbert transform plays in the one-dimensional case. This operator appears to be a singular integral with variable coefficients which is a variant of the maximal double Hilbert transform.
On quasidifferentiable optimization
Authors: Craven B. D.
Published: April 2009

Lagrangian necessary conditions for optimality, of both Fritz John and Kuhn Tucker types, are obtained for a constrained minimization problem, where the functions are locally Lipschitz and have directional derivatives, but need not have linear Gâteaux derivatives; the variable may be constrained to lie in a nonconvex set. The directional derivatives are assumed to have some convexity properties as functions of direction; this generalizes the concept of quasidifferentiable function. The convexity is not required when directional derivatives are replaced by Clarke generalized derivatives. Sufficient Kuhn Tucker conditions, and a criterion for the locally solvable constraint qualification, are obtained for directionally differentiable functions.
Odd triperfect numbers are divisible by twelve distinct prime factors
Authors: Kishore Masao
Published: April 2009

We prove that an odd triperfect number has at least twelve distinct prime factors.
Cartan-Whitehead decomposition as Adams cocompletion
Authors: Behera A. , Nanda S.
Published: April 2009

Deleanu, Frei and Hilton have developed the notion of generalized Adams completion in a categorical context; they have also suggested the dual notion, namely, the Adams cocompletion of an object in a category. In this paper the different stages of the Cartan-Whitehead decomposition of a 0-connected space are shown to be the cocompletions of the space with respect to suitable sets of morphisms.
Infinite non-linear programming
Authors: Hanson M. A.
Published: April 2009

In recent years there has been extensive development in the theory and techniques of mathematical programming in finite spaces. It would be very useful in practice to extend this development to infinite spaces, in order to treat more realistically the problems that arise for example in economic situations involving infinitely divisible processes, and in particular problems involving time as a continuous variable. A more mathematical reason for seeking such generalisation is possibly that of obtaining a unification mathematical programming with other branches of mathematics concerned with extrema, such as the calculus of variations.
Monogenic normal systems are universal
Authors: Arbib Michael A.
Published: April 2009

In 1943, Post conjectured that “monogenic normal systems are universal”, and in 1961 Minsky proved a stronger result “‘tag’ systems are universal” which implied the proof of Post's conjecture. The author had independently obtained a simple direct proof of Post's conjecture. The purpose of this note, then, is to present an exposition of Post's conjecture, and to show the full simplicity of its direct verification.
Diploid populations with selection depending on gene frequency
Authors: Ewens W. J.
Published: April 2009

We consider the case of a genetic population for which the selective advantages of the various genotypes are not constant but for each generation depend linearly on the gene frequencies in the population in the previous generation. For such populations, the effect of competition between similar genotypes may be allowed for by suitable choice of the frequency-dependent selective advantages, or, by a reversal of sign, the case where genotypes are favoured by the presence of similar genotypes may also be considered. favoured by the presence of similar genotypes may also be considered. All populations are finite and of constant size so that eventually only one type of gene will survive. The probabilities of survival for each gene are found and compared with the case where there are no frequency-dependent factors. If a small amount of mutation is allowed, gene fixation will not occur and a steady-state distribution of gene frequency will appear. The form of this distribution may be derived simply from the survival probabilities in the corresponding cases where there is no mutation. The main result is that in some cases, frequency-dependent factors have a marked effect on survival probabilities, while in other cases they can be completely ignored. The latter wifi only occur in certain cases where there exists competition between similar genotypes.
The mean time for absorption in a process of genetic type
Authors: Ewens W. J.
Published: April 2009

We consider the genetic model introduced by Moran [3] of a haploid population of fixed sizeMwith two genotypesAandafor which the possibility of selection is allowed. In this model an individual is randomly chosen to die and is replaced by a new individual whose probability of beingadepends on the selective advantages of the two genotypes and on the number ofaindividuals before the birth-death event. The probability of eventual elimination of the genotypea, both with and without selection, has been found by Moran [3], while Watterson [4] has found the mean time for absorption and the variance in the case where no selection is allowed. We derive here the mean time and the variance in the case where selection is allowed, thus extending Watterson's result. A diffusion approximation is available for the mean time; it is shown that this gives a very close approximation to the exact value. Comparison is made with the non-overlapping generation model due to Wright [5], and finally some numerical results are exhibited.
Pascal's theorem in n–space
Authors: Mandan Sahib Ram
Published: April 2009

An analogue in a solid of the well known Pascal's theorem (Baker, [1], p. 219) for a conic is established by Baker ([2], pp. 53–54, Ex. 15) after Chasles [6] and by Salmon ([2], p. 142). The same is discussed in detail by Court [8]. The purpose of this paper is to extend it to a projective space of n dimensions or briefly to an n-space Sn. To prove it, we introduce here once again the idea of a set of n+1 associated lines in Sn as indicated in an earlier work (Mandan, [12]) in analogy with a set of 5 associated lines in S4 (Baker, [4], p. 122), and make use of the method of induction.
Altitudes of a general n–simplex
Authors: Mandan Sahib Ram
Published: April 2009

The purpose of this paper is to prove that the altitudes of an n-simplex (a simplexin an n-space) S form an associated set of n+1 lines (see Baker, [4] for n = 4) such that any (n–2)-space meeting n of them meets the (n+1)th too. As an immediate consequence 2 quadrics are associated with S, one touching its primes at the respective feet of its altitudes and the other touching n(n+1) primes, n parallel to each of its altitudes and 2 through each of its (n−2)-spaces. Certain special cases are also mentioned.
Gravity effects in the water entry problem
Authors: Mackie A. G.
Published: April 2009

The following paper is a sequel to the author's earlier paper [2]. In that paper some general results were obtained which described the motion of a fluid with a free surface subsequent to a given initial state and prescribed boundary conditions of a certain type. The analysis was based on a linearized theory but gravity effects were included. Viscosity, compressibility and surface tension effects were neglected. Among the problems treated was that of the normal symmetric entry of a thin wedge into water at rest. This Water entry problem has attracted a considerable amount of attention since the pioneer paper by Wagner [5]. Both linear and non-linear approximations have been used but all papers apart from [2] neglect gravity on the assumption that in the early stages of the penetration this is unimportant. One of the objects of [2] was to determine the solution with the gravity terms retained. A formal solution was obtained but no attempt was made to analyse this quantitatively. In the present paper we examine the extent of this effect in some detail. It will be of help to the reader to have some familiarity with the first three or four sections of [2] but in order to make the present paper self-contained we shall first reintroduce the notation used there and quote the necessary results from that paper without proof.
Invariant measures on double coset spaces
Authors: Liu Teng-Sun
Published: April 2009

Let G be a locally compact group with left invariant Haar measure m. Le H be a closed subgroup of G and K a compact group of G. Let R be the equivalence relation in G defined by (a, b)∈R if and if a = kbh for some k in K and h in H. We call E =G/R the double coset space of G modulo K and H. Donote by a the canonical mapping of G onto E. It can be shown that E is a locally compact space and α is continous and open Let N be the normalizer of K in G, i. e. .
An analogue of the Hadamard conjecture for n × n matrices with n ≡2 (mod 4)
Authors: Little Charles H. C.
Published: April 2009

It is known that the problem of settling the existence of an n × n Hadamard matrix, where n is divisible by 4, is equivalent to that of finding the cardinality of a smallest set T of 4-circuits in the complete bipartite graph Kn, n such that T contains at least one circuit of each copy of K2,3 in Kn, n. Here we investigate the case where n ≡ 2 (mod 4), and we show that the problem of finding the cardinality of T is equivalent to that of settling the existence of a certain kind of n × n matrix. Moreover, we show that the case where n ≡ 2 (mod 4) differs from that where n ≡ 0 (mod 4) in that the problem of finding the cardinality of T is not equivalent to that of maximising the determinant of an n × n (1,-1)-matrix.
The strong radical and the left regular representation
Authors: Tomiuk B. J. , Price J. F.
Published: April 2009

Let A be a semisimple modular annihilator Banach algebra and let LA be the left regular representation of A. We show how the strong radical of A is related to the strong radical of LA.
Growth sequences of finite semigroups
Authors: Wiegold James , Lausch H.
Published: April 2009

The growth sequence of a finite semigroup S is the sequence {d(Sn)}, where Sn is the nth direct power of S and d stands for minimum generating number. When S has an identity, d(Sn) = d(Tn) + kn for all n, where T is the group of units and k is the minimum number of generators of S mod T. Thus d(Sn) is essentially known since d(Tn) is (see reference 4), and indeed d(Sn) is then eventually piecewise linear. On the other hand, if S has no identity, there exists a real number c > 1 such that d(Sn) ≥ cn for all n ≥ 2.
Support of the joint spectral measure
Authors: Niechwiej Jan , Vyborny R. O.
Published: April 2009

For a doubly commuting n-tuple of unbounded normal operators in a Hilbert space the joint spectral measure can be constructed and its closed support described as the joint spectrum of the given n-tuple. The same is here shown for larger, possibly uncountable, families of operators.
A generalization of Hermite's interpolation formula in two variables
Authors: Chawla M. M. , Jayarajan N.
Published: April 2009

Spitzbart [1] has considered a generalization of Hermite's interpolation formula in one variable and has obtained a polynomial p(x) of degree n + Σnj=0 = rj in x which interpolates to the values of a function and its derivatives up to order rj at xj, j = 0, 1,···n. Ahlin [2] has considered a bivariate generalization of Hermite's interpolation formula. He has developed a bivariate osculatory interpolation polynomial which agrees with f(x, y) and its partial and mixed partial derivatives up to a specified order at each of the nodes of a Cartesian grid. However, the above interpolation problem considered by Ahlin assumes that the values of partial and mixed partial derivatives of the same fixed order k – 1 are available at every point of the rectangular grid. It may also be observed that Ahlin's formula is essentially a Cartesian product of a special case of Spitzbart's formula in one variable.
A theorem on connected graphs in which every edge belongs to a 1-factor
Authors: Little Charles H. C.
Published: April 2009

In this paper, we consider factor covered graphs, which are defined basically as connected graphs in which every edge belongs to a 1-factor. The main theorem is that for any two edges e and e′ of a factor covered graph, there is a cycle C passing through e and e′ such that the edge set of C is the symmetric difference of two 1-factors.
A note on extensions of Baer and P. P. -rings
Authors: Armendariz Efraim P.
Published: April 2009

Baer rings are rings in which the left (right) annihilator of each subset is generated by an idempotent [6]. Closely related to Baer rings are left P.P.-rings; these are rings in which each principal left ideal is projective, or equivalently, rings in which the left annihilator of each element is generated by an idempotent. Both Baer and P.P.-rings have been extensively studied (e.g. [2], [1], [3], [7]) and it is known that both of these properties are not stable relative to the formation of polynomial rings [5]. However we will show that if a ring R has no nonzero nilpotent elements then R[X] is a Baer or P.P.-ring if and only if R is a Baer or P.P.-ring. This generalizes a result of S. Jøndrup [5] who proved stability for commutative P.P.-rings via localizations – a technique which is, of course, not available to us. We also consider the converse to the well-known result that the center of a Baer ring is a Baer ring [6] and show that if R has no nonzero nilpotent elements, satisfies a polynomial identity and has a Baer ring as center, then R must be a Baer ring. We include examples to illustrate that all the hypotheses are needed.
Dacey Graphs
Authors: Sumner David P.
Published: April 2009

In this paper our graphs will be finite, undirected, and without loops or multiple edges. We will denote the set of vertices of a graph G by V(G). If G is a graph and u, v∈V(G), then we will write u ∼ v to denote that u and v are adjacent and u ≁ v otherwise. If A ⊆ V(G), then we let N(A) = {u∈ V(G)|u ∼ a for each a ∈A}. However we write N(v) instead of N({v}). When there is no chance of confusion, we will not distinguish between a subset A ⊆ V(G) of vertices of G and the subgraph that it induces. We will denote the cardinality of a set A by |A|. The degree of a vertex v is δ(v) = |N(v)|. Any undefined terminology in this paper will generally conform with Behzad and Chartrand [1].
The multidimensional fundamental theorem of calculus
Authors: Pfeffer Washek F.
Published: April 2009

On compact oriented differentiable manifolds, we define a well behaved Riemann type integral which coincides with the Lebesgue integral on nonnegative functions, and such that the exterior derivative of a differentiable (not necessarily continuously) exterior form is always integrable and the Stokes formula holds.
A characterisation of ergodic measures
Authors: Nillsen Rodney
Published: April 2009

Consider a set x together with a σ-algebra B of subsets of x. Let G be a family of B-measurable transformations on x, let p(X) be the convex set of all prbability measures on B and let I be the convex set of all G-invariant probablity measures in p(X). For μµ p(X) we define Bµ = {A ∈ B: µ(g A Δ A) = 0 for all g ∈ G} and we define B0 = {A ∈B: gA = A for all g ∈ G}. Then B0 ⊆ Bµ and both are σ-subalgebras of B. G is said to act transitively on X if for x ∈ X, y ∈ X, gx = y for some g ∈ G.
Locally compact tight Riesz groups
Authors: Wirth Andrew
Published: April 2009

It is known that a strongly archimedean locally compact tight Riesz group without pseudozeros is essential Rm with the usual topology and tight order. We show that a locally compact tight Riesz group, (G, ≦), without pseudozeros, is algebraically and topologically isomorphic with Rm ⊕ D, where D is discrete. Rm ⊕ {0} is a clopen oideal; and we give necessary and sufficient conditions for G to be isomorphic with Rm ⊕ D in all respects. Further (G, ≦) contains an oideal isomorphic with Rm ⊕ ∑ℵZ and G is isomorphic with it if and only if (G, ≦, U) is interval-compact.
On Fixed Points of Asymptotically Regular Mappings
Authors: Rhoades B. E. , sessa S. , Khan M. S. , Swaleh M.
Published: April 2009

Some results on fixed points of asymptotically regular mappings are obtained in complete metric spaces and normed linear spaces.

The structure of the set of common fixed points is also discussed in Banach spaces. Our work generalizes essentially known results of Das and Naik, Fisher, Jaggi, Jungck, Rhoades, Singh and Tiwari and several others.
A Characterization and a Variational Inequality for the Multivariate Normal Distribution
Authors: Stadje Wolfgang
Published: April 2009

Various generalizations of the Maxwell characterization of the multivariate standard normal distribution are derived. For example the following is proved: If for a k-dimensional random vector X there exists an n ∈ {l, …, k − l} such that for each n-dimensional linear subspace H Rk the projections of X on H and H⊥ are independent, X is normal. If X has a rotationally symmetric density and its projection on some H has a density of the same functional form, X is normal. Finally we give a variational inequality for the multivariate normal distribution which resembles the isoperimetric inequality for the surface measure on the sphere.
On Topological Algebra Bundles
Authors: Kyriazia Athanasios
Published: April 2009

Topological algebra bundles whose fibre (-algebras) admit functional representations constitute a category, antiequivalent with that of (topological) fibre bundles having completely regular bundle spaces and locally compact fibres.
Chief Series and Right Regular Representations of Finite p-Groups
Authors: Leinen Felix
Published: April 2009

We study the embeddings of a finite p-group U into Sylow p-subgroups of Sym (U) induced by the right regular representation p: U→ Sym(U). It turns out that there is a one-to-one correspondence between the chief series in U and the Sylow p-subgroups of Sym (U) containing Up. Here, the Sylow p-subgroup Pσ of Sym (U) correspoding to the chief series σ in U is characterized by the property that the intersections of Up with the terms of any chief series in Pσ form σp. Moreover, we see that p: U→ Pσ are precisely the kinds of embeddings used in a previous paper to construct the non-trivial countable algebraically closed locally finite p-groups as direct limits of finite p-groups.
Almost everywhere convergence of lacunary trigonometric series with respect to Riesz products
Authors: PeyriÈre J.
Published: April 2009

Let {λj}j≥0 be a sequence of positive integers such that λj+1/λj≥3 and {aj}j≥0 a sequence of complex numbers such that |aj|≤1. Let μ be the Riesz product πj≥0[1+ Re(ajeiλjx)], that is, the weak limit of measures on T the density of which are the partial products. Then if Σj≥0|aj|2≤∞ the series Σj≥0 aj(eiλjx - ½āj) converges for μ-almost every x. The μ-a.e. convergence of series Σ ajeinλjx is also investigated as well as the case of Riesz products on a compact commutative group.
Factorization of invertible matrices over rings of stable rank one
Authors: Vaserstein Leonid N. , Wheland Ethel
Published: April 2009

Every invertible n-by-n matrix over a ring R satisfying the first Bass stable range condition is the product of n simple automorphisms, and there are invertible matrices which cannot be written as the products of a smaller number of simple automorphisms. This generalizes results of Ellers on division rings and local rings.
On immersions of N-manifolds in codimension N − 1
Authors: Aguilar M. A. , Pastor G.
Published: April 2009

We give a simple proof, using only classical algebraic topology, of the following theorem of B. H. Li and F. P. Peterson. Any map from an N-manifold into a (2N − 1)-manifold is homotopic to an immersion.
On measurable multifunctions with stochastic domain
Authors: Papageorgiou Nikolaos S.
Published: April 2009

In this paper we prove several random fixed point theorems for multifunctions with a stochastic domain. Then those techniques are used to establish the existence of solutions for random differential inclusions. A useful tool in this process is a stochastic version of the Tietze extension theorems that we prove. Finally we present a stochastic version of the Riesz representation theorem for Hilbert spaces.
Operators related to idempotent generated and monoid completely regular semigroups
Authors: Petrich Mario , Reilly Norman R.
Published: April 2009

The class CR of completely regular semigroups (unions of groups or algebras with the associative binary operation of multiplication and the unary operation of inversion subject to the laws x = xx-1, (x−1)-1 = x and xx-1 = x-1x) is a variety. Among the important subclasses of CR are the classes M of monoids and I of idempotent generated members. For each C ∈ {I, M}, there are associated mappings ν → ν ∩ C and ν → (Ν ∩ C), the variety generated by ν ∩ C. The lattice theoretic properties of these mappings and the interactions between these mappings are studied.
The lattice of completely regular semigroup varieties
Authors: Pastijn Francis
Published: April 2009

A completely regular semigroup is a semigroup which is a union of groups. The class CR of completely regular semigroups forms a variety. On the latticeL(CR) of completely regular semigroup varieties we define two closure operations which induce complete congruences. The consideration of a third complete congruence onL(CR) yields a subdirect decomposition ofL(CR). Using these results we show thatL(CR) is arguesian. This confirms the (tacit) conjecture thatL(CR) is modular.
Weakly reductive semigroups with atomistic congruence lattices
Authors: Auinger Karl
Published: April 2009

The structure of semigroups with atomistic congruence lattices (that is, each congruence is the supremum of the atoms it contains) is studied. For the weakly reductive case the problem of describing the structure of such semigroups is solved up to simple and congruence free semigroups, respectively. As applications, all commutative, finite, completely semisimple semigroups, respectively, with atomistic congruence lattices are described.
Varieties of groups and isologisms
Authors: Hekster N. S.
Published: April 2009

In order to classify solvable groups Philip Hall introduced in 1939 the concept of isoclinism. Subsequently he defined a more general notion called isologism. This is so to speak isoclinism with respect to a certain variety of groups. The equivalence relation isologism partitions the class of all groups into families. The present paper is concerned with the internal structure of these families.
The Hadamard three-circles theorems for nonlinear equations
Authors: Výborný R.
Published: April 2009

The aim of this paper is is to establish Hadamard's type three-circles theorems for fully nonlinear elliptic and parabolic inequalities.