bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical scheme on numerical conformal mapping of unbounded multiply connected domain by fundamental solutions method
Authors: Inoue Tetsuo , Kuhara Hideo , Amano Kaname , Okano Dai
Published: September 2002

A potentially theoretical scheme in the fundamental solutions
method, different from the conventional one, is proposed for
numerical conformal mappings of unbounded multiply connected
domains. The scheme is introduced from an algorithm on numerical
Dirichlet problem, based on the asymptotic theorem on extremal
weighted polynomials. The scheme introduced in this paper has the
characteristic called “invariant and dual.”
On almost precontinuous functions
Authors: Jafari Saeid , Noiri Takashi
Published: September 2002

Nasef and Noiri (1997) introduced and investigated the class of
almost precontinuous functions. In this paper, we further
investigate some properties of these functions.
New characterizations of some Lp‐spaces
Authors: Jenkins Russell S. , Garimella Ramesh V.
Published: September 2002

For a complete measure space (X, ∑, μ), we give conditions
which force Lp(X, μ), for 1 ≤ p < ∞, to be isometrically isomorphic to ℓp(Γ) for some index set
Γ which depends only on (X, μ). Also, we give some new
characterizations which yield the inclusion Lp(X, μ) ⊂ Lq(X, μ) for 0 < p < q.
Small bound isomorphisms of the domain of a closed ∗‐derivation
Authors: Matsumoto Toshiko , Watanabe Seiji
Published: September 2002

The domain 𝒟(δ) of a closed ∗‐derivation δ in C(K) (K: a compact Hausdorff
space) is a generalization of the space C(1)[0, 1] of
differentiable functions on [0, 1]. In this paper, a problem
proposed by Jarosz (1985) is studied in the context of derivations
instead of C(1)[0, 1].
Variation of constants formulae for difference equations with advanced arguments
Authors: Díaz Lolimar , Naulin Raúl
Published: September 2002

The construction of a variation of constants formula for the
difference equation with advanced arguments
y(n + 1) = A(n)y(n) + B(n)y(g(n)) + f(n), g(n) ≥ n + 1, is given for
specific sequential spaces.
Classes of convex functions
Authors: Rosy Thomas , Stephen B. Adolf , Subramanian K. G. , Silverman Herb
Published: September 2002

We investigate a family that connects various subclasses of
functions convex in the unit disk. We also look at generalized
sequences for this family.
Approximating fixed points of nonexpansive mappings
Authors: Liu Guimei , Lei Deng , Li Shenghong
Published: September 2002

We consider a mapping S of the form

urn:x-wiley:01611712:media:ijmm542948:ijmm542948-math-0001

,
where αi ≥ 0, α0 > 0, α1 > 0 and
. We show that the Picard iterates of
S converge to a common fixed point of Ti(i = 1,2,…,k)in a Banach space when Ti(i = 1,2,…,k) are
nonexpansive.
Ishikawa iteration process with errors for nonexpansive mappings in uniformly convex Banach spaces
Authors: Lei Deng , Shenghong Li
Published: September 2002

We shall consider the behaviour of Ishikawa iteration with errors
in a uniformly convex Banach space. Then we generalize the two
theorems of Tan and Xu without the restrictions that C is bounded
and limsupnsn < 1.
A note on commutativity of nonassociative rings
Authors: Khan M. S. S.
Published: September 2002

A theorem on commutativity of nonassociate ring is given.
On an isolation and a generalization of Hölder′s inequality
Authors: Yang Xiaojing
Published: September 2002

We generalize the well‐known Hölder inequality and give a condition at which the
equality holds.
On characterizations of a center Galois extension
Authors: Szeto George , Xue Lianyong
Published: September 2002

Let B be a ring with 1,   C the center of B,   G a finite
automorphism group of B, and BG the set of elements in B
fixed under each element in G. Then, it is shown that B is a
center Galois extension of BG (that is, C is a Galois algebra
over CG with Galois group G|C≅G) if and only if the
ideal of B generated by {c − g(c) | c ∈ C} is B for each
g ≠ 1 in G. This generalizes the well known characterization
of a commutative Galois extension C that C is a Galois
extension of CG with Galois group G if and only if the ideal
generated by {c − g(c) | c ∈ C} is C for each g ≠ 1 in
G. Some more characterizations of a center Galois extension B
are also given.
On rational approximation in a ball in ℂN
Authors: Darko P. W. , Einstein-Matthews S. M. , Lutterodt C. H.
Published: September 2002

We study rational approximations of
elements of a special class of meromorphic functions which are
characterized by their holomorphic behavior near the origin in
balls in ℂN by means of their rational approximants. We
examine two modes of convergence for this class: almost
uniform‐type convergence analogous to Montessus‐type convergence
and weaker form of convergence using capacity based on the
classical Tchebychev constant. These methods enable us to
generalize and extend key results of Pommeranke and Gonchar.
ℵ1‐directed inverse systems of continuous images of arcs
Authors: Lončar Ivan
Published: September 2002

The main purpose of this paper is to prove that if X = {Xa, pab, A} is a usual ℵ1‐directed inverse system
of continuous images of arcs with monotone bonding mappings, then
X = limX is a continuous image of an arc
(Theorem 2.4). Some applications of this statement are also
given.
Composition of functions
Authors: Muthuvel Kandasamy
Published: September 2002

We prove that if f and g are functions from the reals into
the reals such that the composition of g with f is continuous
and f is both Darboux and surjective, then g is continuous. We
also prove that continuous and Darboux can be interchanged in the
above statement.
A unified theory for weak separation properties
Authors: Küçük Mahide , Zorlutuna İdris
Published: September 2002

We devise a framework which leads to the formulation of a unified
theory of normality (regularity), semi‐normality (semi‐regularity),
s‐normality (s‐regularity), feebly‐normality
(feebly‐regularity), pre‐normality (pre‐regularity), and others.
Certain aspects of theory are given by unified proof.
Ordered groups with greatest common divisors theory
Authors: Močkoř Jiří
Published: September 2002

An embedding (called a GCD theory) of partly ordered
abelian group G into abelian l‐group Γ is investigated
such that any element of Γ is an infimum of a subset
(possible non‐finite) from G. It is proved that a GCD theory need
not be unique. A complete GCD theory is introduced and it is
proved that G admits a complete GCD theory if and only if it
admits a GCD theory G → Γ such that Γ is an
Archimedean l‐group. Finally, it is proved that a complete GCD
theory is unique (up to o‐isomorphisms) and that a po‐group
admits the complete GCD theory if and only if any v‐ideal is
v‐invertible.
Multipliers of Banach valued weighted function spaces
Authors: Öztop Serap
Published: September 2002

We generalize Banach valued spaces to Banach valued
weighted function spaces and study the multipliers space of these
spaces. We also show the relationship between multipliers and
tensor product of Banach valued weighted function spaces.
An example of nonsymmetric semi‐classical form of class s = 1; generalization of a case of Jacobi sequence
Authors: Atia Mohamed Jalel
Published: September 2002

We give explicitly the recurrence coefficients of a nonsymmetric
semi‐classical sequence of polynomials of class s = 1. This
sequence generalizes the Jacobi polynomial sequence, that is, we
give a new orthogonal sequence , where μ is an arbitrary parameter with ℜ(1 − μ) > 0 in such a way that for μ = 0 one has the well‐known Jacobi polynomial sequence , n ≥ 0.
Boehmians on manifolds
Authors: Mikusiński Piotr
Published: September 2002

The construction of Boehmians on a manifold requires a commutative
convolution structure. We present such constructions in two specific cases:
an N‐dimensional torus and an N‐dimensional sphere. Then we formulate
conditions under which a construction of Boehmians on a manifold is possible.
Some maximum principles for solutions of a class of partial differential equations in Ω ⊂ ℝn
Authors: Al-Mahameed Mohammad Mujalli
Published: September 2002

We find maximum principles for solutions of semilinear elliptic
partial differential equations of the forms: (1) Δ2u + αf(u) = 0, α ∈ ℝ+ and (2) ΔΔu + α(Δu) k + gu = 0, α ≤ 0 in some region
Ω ⊂ ℝn.
Shallow water waves in a rotating rectangular basin
Authors: Helal Mohamed Atef
Published: September 2002

This paper is mainly concerned with the motion of an incompressible
fluid in a slowly rotating rectangular basin. The equations of
motion of such a problem with its boundary conditions are reduced
to a system of nonlinear equations, which is to be solved by
applying the shallow water approximation theory. Each unknown of
the problem is expanded asymptotically in terms of the small
parameter ϵ which generally depends on some intrinsic
quantities of the problem of study. For each order of
approximation, the nonlinear system of equations is presented
successively. It is worthy to note that such a study has useful
applications in the oceanography.
Rayleigh‐Benard convection in a viscoelastic fluid‐filled high‐porosity medium with nonuniform basic temperature gradient
Authors: Siddheshwar Pradeep G. , Sri Krishna C. V.
Published: September 2002

The qualitative effect of nonuniform temperature gradient on the
linear stability analysis of the Rayleigh‐Benard convection
problem in a Boussinesquian, viscoelastic fluid‐filled,
high‐porosity medium is studied numerically using the single‐term
Galerkin technique. The eigenvalue is obtained for free‐free,
free‐rigid, and rigid‐rigid boundary combinations with isothermal
temperature conditions. Thermodynamics and also the
present stability analysis dictates the strain retardation time
to be less than the stress relaxation time for convection to set
in as oscillatory motions in a high‐porosity medium. Furthermore,
the analysis predicts the critical eigenvalue for the viscoelastic
problem to be less than that of the corresponding Newtonian fluid
problem.
Tautness and applications of the Alexander‐Spanier cohomology of K‐types
Authors: Dabbour Abd El-Sattar A. , Hijazi Rola A.
Published: September 2002

The aim of the present work is centered around the tautness
property for the two K‐types of Alexander‐Spanier cohomology
given by the authors. A version of the continuity property is
proved, and some applications are given.
Regular‐uniform convergence and the open‐open topology
Authors: Porter Kathryn F.
Published: September 2002

In 1994, Bânzaru introduced the concept of regular‐uniform, or r‐uniform, convergence on a family of functions. We discuss the
relationship between this topology and the open‐open topology,
which was described in 1993 by Porter, on various collections of
functions.
On a stochastic inventory model with deteriorating items
Authors: Aggoun L. , Benkherouf L. , Tadj L.
Published: September 2002

We suggest a new inventory continuous time stochastic model for
deteriorating items. We derive optimal operating characteristics of
the expected cost per unit time under the assumption that
demand in each replenishment cycle forms a regenerative process.
We also present numerical examples.
Asymptotic behaviour of solutions for porous medium equation with periodic absorption
Authors: Jingxue Yin , Yifu Wang
Published: September 2002

This paper is concerned with porous medium equation with periodic absorption. We are interested in the discussion of asymptotic behaviour of solutions of the first boundary value problem for the equation. In contrast to the equation without sources, we show that the solutions may not decay but may be “attracted” into any small neighborhood of the set of all nontrivial periodic solutions, as time tends to infinity. As a direct consequence, the null periodic solution is “unstable.” We have presented an accurate condition on the sources for solutions to have such a property. Whereas in other cases of the sources, the solutions might decay with power speed, which implies that the null periodic solution is “stable.”
On some classes of BCH‐algebras
Authors: Chaudhry Muhammad Anwar , Fakhar-Ud-Din Hafiz
Published: September 2002

The concept of a BCH‐algebra is a generalization of the concept of
a BCI‐algebra. It is shown that weakly commutative BCH‐algebras are
weakly commutative BCI‐algebras. Moreover, the concepts of weakly
positive implicative and weakly implicative BCH‐algebras are
defined and it is shown that every weakly implicative BCH‐algebra
is a weakly positive implicative BCH‐algebra. The weakly positive
implicative BCH‐algebras are characterized with the help of their
self maps. Two open problems are posed.
Two‐weight norm inequalities for the rough fractional integrals
Authors: Ding Yong , Lin Chin-Cheng
Published: September 2002

The authors give the weighted (Lp, Lq)‐boundedness of the
rough fractional integral operator TΩ,α and the
fractional maximal operator MΩ,α with two
different weight functions.
The initial boundary value problem of a mixed‐typed hemivariational inequality
Authors: Xingming Guo
Published: September 2002

A mixed‐typed differential inclusion with a weakly continuous
nonlinear term and a nonmonotone discontinuous nonlinear
multi‐valued term is studied, and the existence and decay of
solutions are established.
Experiment on numerical conformal mapping of unbounded multiply connected domain in fundamental solutions method
Authors: Inoue Tetsuo , Kuhara Hideo , Amano Kaname , Okano Dai
Published: September 2002

We are concerned with the experiment on numerical conformal mappings. A potentially theoretical scheme in the fundamental solutions method, different from the conventional one, has been recently proposed for numerical conformal mappings of unbounded multiply connected domains. The scheme is based on the asymptotic theorem on extremal weighted polynomials. The scheme has the characteristic called “invariant and dual.” Applying the scheme for typical examples, we will show that the numerical results of high accuracy may be obtained.
Topological degree and application to a parabolic variational inequality problem
Authors: Addou A. , Mermri B.
Published: September 2002

We are interested in constructing a topological degree for operators of the
form F = L + A + S, where L is a linear densely defined maximal
monotone map, A is a bounded maximal monotone operators, and S is a bounded demicontinuous map of class (S+) with respect to
the domain of L. By means of this topological degree we prove an
existence result that will be applied to give a new formulation of
a parabolic variational inequality problem.
Statistical applications for equivariant matrices
Authors: Alkarni S. H.
Published: September 2002

Solving linear system of equations Ax = b enters into many
scientific applications. In this paper, we consider a special kind
of linear systems, the matrix A is an equivariant matrix with
respect to a finite group of permutations. Examples of this kind
are special Toeplitz matrices, circulant matrices, and others. The
equivariance property of A may be used to reduce the cost of
computation for solving linear systems. We will show that the
quadratic form is invariant with respect to a permutation matrix.
This helps to know the multiplicity of eigenvalues of a matrix and
yields corresponding eigenvectors at a low computational cost.
Applications for such systems from the area of statistics will be
presented. These include Fourier transforms on a symmetric group as
part of statistical analysis of rankings in an election, spectral
analysis in stationary processes, prediction of stationary
processes and Yule‐Walker equations and parameter estimation for
autoregressive processes.
On certain analytic univalent functions
Authors: Frasin B. A. , Darus M.
Published: September 2002

We consider the class of analytic functions B(α) to
investigate some properties for this class. The angular estimates
of functions in the class B(α) are obtained. Finally, we derive some interesting conditions for the class of strongly
starlike and strongly convex of order α in the open unit disk.
Note on the quadratic Gauss sums
Authors: Danas George
Published: September 2002

Let p be an odd prime and
{χ(m) = (m/p)}, m = 0, 1, …, p − 1 be a finite arithmetic sequence with elements the values of a
Dirichlet character χ  modp which are defined in terms of
the Legendre symbol (m/p), (m, p) = 1. We study the relation
between the Gauss and the quadratic Gauss sums. It is shown that
the quadratic Gauss sums G(k; p) are equal to the Gauss sums
G(k, χ) that correspond to this particular Dirichlet
character χ. Finally, using the above result, we prove that
the quadratic Gauss sums G(k; p), k = 0, 1, …, p − 1are
the eigenvalues of the circulant p × p matrix X with
elements the terms of the sequence {χ(m)}.
On the Diophantine equation Ax2 + 22m = yn
Authors: Abu Muriefah Fadwa S.
Published: September 2002

Let h denote the class number of the quadratic field for a square free odd integer A > 1,
and suppose that n > 2 is an odd integer with (n, h) = 1 and m > 1. In this paper, it is proved that the equation of the title
has no solution in positive integers x and y if n has any
prime factor congruent to 1 modulo 4. If n has no such factor it is proved that there exists at most one solution with x and y odd. The case n = 3 is solved completely. A result of E.
Brown for A = 3 is improved and generalized to the case where A is a prime ≢7(mod8)
.
Fuzzy BCI‐subalgebras with interval‐valued membership functions
Authors: Hong Sung Min , Jun Young Bae , Kim Seon Jeong , Kim Gwang Il
Published: September 2002

The purpose of this paper is to define the notion of an
interval‐valued fuzzy BCI‐subalgebra (briefly, an i‐v fuzzy
BCI‐subalgebra) of a BCI‐algebra. Necessary and sufficient
conditions for an i‐v fuzzy set to be an i‐v fuzzy BCI‐subalgebra
are stated. A way to make a new i‐v fuzzy BCI‐subalgebra from old
one is given. The images and inverse images of i‐v fuzzy
BCI‐subalgebras are defined, and how the images or inverse images
of i‐v fuzzy BCI‐subalgebras become i‐v fuzzy BCI‐subalgebras is
studied.
On almost (N, p, q) summability of conjugate Fourier series
Authors: Lal Shyam , Nigam Hare Krishna
Published: September 2002

A new theorem on almost generalized Nörlund summability of
conjugate series of Fourier series has been established under a
very general condition.
A Gauss type functional equation
Authors: Toader Silvia , Rassias Themistocles M. , Toader Gheorghe
Published: September 2002

Gauss′ functional equation (used in the study of the
arithmetic‐geometric mean) is generalized by replacing the
arithmetic mean and the geometric mean by two arbitrary means.
Submanifolds of F‐structure manifold satisfying FK + (−)K+1F = 0
Authors: Das Lovejoy S.
Published: September 2002

The purpose of this paper is to study invariant submanifolds of an n‐dimensional manifold M endowed with an F‐structure satisfying FK + (−)K+1F = 0 and FW + (−)W+1F ≠ 0 for 1 < W < K, where K is a fixed positive integer greater than 2. The case when K is odd (≥3) has been considered in this paper. We show that an invariant submanifold , embedded in an F‐structure manifold M in such a way that the complementary distribution Dm is never tangential to the invariant submanifold , is an almost complex manifold with the induced ‐structure. Some theorems regarding the integrability conditions of induced ‐structure are proved.
A functional equation characterizing cubic polynomials and its stability
Authors: Jung Soon-Mo , Sahoo Prasanna K.
Published: September 2002

We study the generalized Hyers‐Ulam stability of the functional equation f[x1, x2, x3] = h(x1 + x2 + x3).
On the application of ergodic theory to alternating Engel series
Authors: Ganatsiou C.
Published: September 2002

We investigate the ergodic behaviour of the basic operator which
generates the modified Engel‐type alternating series
representations of any number in (0, 1] in terms of rationals.
Near Frattini subgroups of residually finite generalized free products of groups
Authors: Azarian Mohammad K.
Published: September 2002

Let G = A★HB be the generalized free product of the groups A and B with the amalgamated subgroup H. Also, let λ(G) and ψ(G) represent the lower near Frattini subgroup and the near Frattini subgroup of G, respectively. If G is finitely generated and residually finite, then we show that ψ(G) ≤ H, provided H satisfies a nontrivial identical relation. Also, we prove that if G is residually finite, then λ(G) ≤ H, provided: (i) H satisfies a nontrivial identical relation and A, B possess proper subgroups A1, B1 of finite index containing H; (ii) neither A nor B lies in the variety generated by H; (iii) H < A1 ≤ A and H < B1 ≤ B, where A1 and B1 each satisfies a nontrivial identical relation; (iv) H is nilpotent.
Ishikawa iteration process with errors for nonexpansive mappings
Authors: Huang Jialin
Published: September 2002

We study the construction and the convergence of the Ishikawa iterative process with errors for nonexpansive mappings in uniformly convex Banach spaces. Some recent corresponding results are generalized.
A note on the comparison of topologies
Authors: Kovár Martin M.
Published: September 2002

A considerable problem of some bitopological covering properties is the bitopological unstability with respect to the presence of the pairwise Hausdorff separation axiom. For instance, if the space is RR‐pairwise paracompact, its two topologies will collapse and revert to the unitopological case. We introduce a new bitopological separation axiom τS2σ which is appropriate for the study of the bitopological collapse. We also show that the property that may cause the collapse is much weaker than some modifications of pairwise paracompactness and we generalize several results of T. G. Raghavan and I. L. Reilly (1977) regarding the comparison of topologies.
Some results on ordered filters of implicative semigroups
Authors: Jun Young Bae
Published: September 2002

We introduce a special set in an implicative semigroup. Using it, an equivalent condition of an ordered filter is stated. We prove that an ordered filter can be represented by the union of such sets.
Generalized periodic and generalized Boolean rings
Authors: Bell Howard E. , Yaqub Adil
Published: September 2002

We prove that a generalized periodic, as well as a generalized Boolean, ring is either commutative or periodic. We also prove that a generalized Boolean ring with central idempotents must be nil or commutative. We further consider conditions which imply the commutativity of a generalized periodic, or a generalized Boolean, ring.
An interarrival hyperexponential machine interference with balking, reneging, state‐dependent, spares, and an additional server for longer queues
Authors: Al-Seedy Ragab Omarah , Al-Ibraheem Fawziah M.
Published: September 2002

The aim of this paper is to treat the analytical solution of the truncated interarrival hyperexponential machine interference queue: H2/M/1/m + Y/m + Y in case of two branches with the following concepts: balking, reneging, state‐dependent, spares, and an additional server for longer queues. Our research treats
the general case for the values of m and Y considering the discipline FIFO. And some special cases have been verified.
Countably I‐Compact Spaces
Authors: Al-Nashef Bassam
Published: September 2002

We introduce the class of countably I‐compact spaces as a proper subclass of countably S‐closed spaces. A topological space (X, T) is called countably I‐compact if every countable cover of X by regular closed subsets contains a finite subfamily whose interiors cover X. It is shown that a space is countably I‐compact if and only if it is extremally disconnected and countably S‐closed. Other characterizations are given in terms of covers by semiopen subsets and other types of subsets. We also show that countable I‐compactness is invariant under almost open semi‐continuous surjections.
On n‐fold fuzzy positive implicative ideals of BCK‐algebras
Authors: Jun Young Bae , Kim Kyung Ho
Published: September 2002

We consider the fuzzification of the notion of an n‐fold positive implicative ideal. We give characterizations of an n‐fold fuzzy positive implicative ideal. We establish the extension property for n‐fold fuzzy positive implicative ideals, and state a characterization of PIn‐Noetherian BCK‐algebras. Finally we study the normalization of n‐fold fuzzy positive implicative ideals.
On some properties of the Lüroth‐type alternating series representations for real numbers
Authors: Ganatsiou C.
Published: September 2002

We investigate some properties connected with the
alternating Lüroth‐type series representations for real numbers,
in terms of the integer digits involved. In particular, we
establish the analogous concept of the asymptotic density and the
distribution of the maximum of the first n denominators, by applying appropriate limit theorems.
Some operations on lattice implication algebras
Authors: Roh E. H. , Kim S. Y. , Xu Y. , Jun Young Bae
Published: September 2002

We introduce the concept of a ⊗‐closed set
and a ⊗‐homomorphism in lattice implication
algebras, and we discuss some of their properties. Next, we
introduce the fuzzy implicative filter and obtain equivalent
conditions. Finally, we discuss the operation
⊗, fuzzy filters and fuzzy implicative
filters.
Some applications of minimal open sets
Authors: Nakaoka Fumie , Oda Nobuyuki
Published: September 2002

We characterize minimal open sets in topological spaces. We show that any nonempty subset of a minimal open set is pre‐open. As an application of a theory of minimal open sets, we obtain a sufficient condition for a locally finite space to be a pre‐Hausdorff space.
The Abel‐type transformations into Gw
Authors: Lemma Mulatu , Tessema George
Published: September 2002

The Abel‐type matrix Aα,t was introduced and studied as a mapping into ℓ by Lemma (1999). The purpose of this paper is to study these transformations as mappings into Gw. The necessary and sufficient conditions for Aα,t to be Gw‐Gw are established. The strength of Aα,t in the Gw‐Gw setting is investigated. Also, it is shown that Aα,t is translative in the Gw‐Gw senses for certain sequences.
On solutions of the Gołąb‐Schinzel equation
Authors: Mureńko Anna
Published: September 2002

We determine the solutions f : (0, ∞) → [0, ∞) of the functional equation f(x + f(x)y) = f(x)f(y) that are continuous at a point a > 0 such that f(a) > 0. This is a partial solution of a problem raised by Brzdęk.
New series involving the zeta function
Authors: Yun-Fei Wu
Published: September 2002

We evaluate sums of certain classes of new series involving the
Riemann zeta function by using the theory of the double gamma
function and a property of the gamma function. Relevant
connections with various known results are also pointed out.
A note on Fibonacci matrices of even degree
Authors: Elia Michele
Published: September 2002

This paper presents a construction of m‐by‐m irreducible Fibonacci matrices for any even m. The proposed technique relies on matrix representations of algebraic number fields which
are an extension of the golden section field. The explicit construction of some 6‐by‐6 and 8‐by‐8 irreducible Fibonacci matrices is given.
Motion of two point vortices in a steady, linear, and elliptical flow
Authors: Gethner Robert M.
Published: September 2002

For a pair of point vortices in an inviscid, incompressible fluid
in the plane, the relative and absolute motion are determined when
the vortices move under the influence of (1) each other, and (2)
a steady, linear, and elliptical background flow.
Subgroups of finite index in an additive group of a ring
Authors: Mojdeh Doostali , Hashemi S. Hassan
Published: September 2002

If K is an infinite field and G⫅K is a subgroup of
finite index in an additive group, then where G∗ denotes the set of all invertible elements
in G and denotes all inverses of elements of G∗. Similar results hold for various fields, division rings and rings.
Explicit solution for an infinite dimensional generalized inverse eigenvalue problem
Authors: Ghanbari Kazem
Published: September 2002

We study a generalized inverse eigenvalue problem (GIEP), Ax = λBx, in which A is a semi‐infinite Jacobi matrix with positive off‐diagonal entries ci > 0, and B =  diag (b0, b1, …), where bi ≠ 0 for i = 0, 1, …. We give an explicit solution by establishing an appropriate spectral function with respect to a given set of spectral data.
Some properties of the ideal of continuous functions with pseudocompact support
Authors: Abu Osba E. A. , Al-Ezeh H.
Published: September 2002

Let C(X) be the ring of all continuous real‐valued
functions defined on a completely regular T1‐space. Let CΨ(X) and CK(X) be the ideal of functions with
pseudocompact support and compact support, respectively.
Further equivalent conditions are given to characterize when an
ideal of C(X) is a P‐ideal, a concept which was originally
defined and characterized by Rudd (1975). We used this new
characterization to characterize when CΨ(X)
is a P‐ideal, in particular we proved that CK(X) is a P‐ideal if and only if CK(X) = {f∈C(X) : f = 0 except on a finite set}. We also used this characterization to prove that for any ideal I contained in CΨ(X), I is an injective C(X)‐module if and only if coz I is finite. Finally, we showed that CΨ(X) cannot be a proper prime ideal while CK(X) is prime if and only if X is an almost compact noncompact space and
∞ is an F‐point. We give concrete examples exemplifying the concepts studied.
Graded subalgebras of the Lie algebra of a smooth manifold
Authors: Paepe Karl De
Published: September 2002

We construct and study finitely generated graded subalgebras of the
Lie algebra of a smooth manifold.
Free objects in the category of geometries
Authors: Al-Hawary Talal Ali
Published: September 2002

The aim of this note is to introduce the class of free geometries purely in terms of morphisms. Several classes of well‐known matroid morphisms are characterized via the new concept.
Fuzzy r‐continuous and fuzzy r‐semicontinuous maps
Authors: Lee Seok Jong , Lee Eun Pyo
Published: September 2002

We introduce a new notion of fuzzy
r‐interior which is an extension of Chang′s fuzzy
interior. Using fuzzy r‐interior, we define fuzzy
r‐semiopen sets and fuzzy
r‐semicontinuous maps which are generalizations of
fuzzy semiopen sets and fuzzy semicontinuous maps in Chang′s fuzzy
topology, respectively. Some basic properties of fuzzy
r‐semiopen sets and fuzzy
r‐semicontinuous maps are investigated.
Extendibility, monodromy, and local triviality for topological groupoids
Authors: Mucuk Osman , İçen İlhan
Published: September 2002

A groupoid is a small category in which each morphism has an
inverse. A topological groupoid is a groupoid in which both sets
of objects and morphisms have topologies such that all maps of
groupoid structure are continuous. The notion of monodromy
groupoid of a topological groupoid generalizes those of
fundamental groupoid and universal cover. It was earlier proved
that the monodromy groupoid of a locally sectionable topological
groupoid has the structure of a topological groupoid satisfying
some properties. In this paper a similar problem is studied for
compatible locally trivial topological groupoids.
Continued fractions and class number two
Authors: Mollin Richard A.
Published: September 2002

We use the theory of continued fractions in conjunction with ideal theory (often called the infrastructure) in real quadratic fields to give new class number 2 criteria and link this to a
canonical norm‐induced quadratic polynomial. By doing so, this provides a real quadratic field analogue of the well‐known result by Hendy (1974) for complex quadratic fields. We illustrate with
several examples.
Development of singularities in solutions of a hyperbolic system
Authors: Messaoudi S. A.
Published: September 2002

We consider a special type of a hyperbolic system and show that
classical solutions blow up in finite time even for small initial data.
On the zeros and critical points of a rational map
Authors: Buff Xavier
Published: September 2002

Let f : ℙ1 → ℙ1 be a rational map of degree d. It is well known that f has d zeros and 2d − 2 critical points counted with multiplicities. In this note, we
explain how those zeros and those critical points are related.
Problems and solutions by the application of Julia set theory to one‐dot and multi‐dots numerical methods
Authors: Tomova Anna
Published: September 2002

In 1977 Hubbard developed the ideas of Cayley (1879) and solved
in particular the Newton‐Fourier imaginary problem. We solve the
Newton‐Fourier and the Chebyshev‐Fourier imaginary problems
completely. It is known that the application of Julia set theory
is possible to the one‐dot numerical method like the Newton′s
method for computing solution of the nonlinear equations. The
secants method is the two‐dots numerical method and the
application of Julia set theory to it is not demonstrated.
Previously we have defined two one‐dot combinations: the
Newton′s‐secants and the Chebyshev′s‐secants methods and have
used the escape time algorithm to analyse the application of
Julia set theory to these two combinations in some special cases.
We consider and solve the Newton′s‐secants and
Tchebicheff′s‐secants imaginary problems completely.
Ergodicity of stochastically forced large scale geophysical flows
Authors: Duan Jinqiao , Goldys Beniamin
Published: September 2002

We investigate the ergodicity of 2D large scale quasigeostrophic
flows under random wind forcing. We show that the quasigeostrophic
flows are ergodic under suitable conditions on the random forcing
and on the fluid domain, and under no restrictions on viscosity,
Ekman constant or Coriolis parameter. When these conditions are
satisfied, then for any observable of the quasigeostrophic flows,
its time average approximates the statistical ensemble average, as
long as the time interval is sufficiently long.
Hot‐pressing process modeling for medium density fiberboard (MDF)
Authors: Nigro Norberto , Storti Mario
Published: September 2002

We present a numerical solution for the mathematical modeling of the hot‐pressing process applied to medium density fiberboard. The model is based on the work of Humphrey (1982), Humphrey and Bolton (1989), and Carvalho and Costa (1998) with some modifications and extensions in order to take into account mainly the convective effects on the phase change term and also a conservative numerical treatment of the resulting system of
partial differential equations.
Iteration of λ‐complete forcing notions not collapsing λ+
Authors: Rosłanowski Andrzej , Shelah Saharon
Published: September 2002

We look for a parallel to the notion of “proper forcing” among λ‐complete forcing notions not collapsing λ+. We suggest such a definition and prove that it is preserved by suitable iterations.
On branchwise implicative BCI‐algebras
Authors: Chaudhry Muhammad Anwar
Published: September 2002

We introduce a new class of BCI‐algebras, namely the class of
branchwise implicative BCI‐algebras. This class contains the
class of implicative BCK‐algebras, the class of weakly implicative
BCI‐algebras (Chaudhry, 1990), and the class of medial BCI‐algebras.
We investigate necessary and sufficient conditions for two types of BCI‐algebras
to be branchwise implicative BCI‐algebras.
Interaction between line cracks in an orthotropic layer
Authors: Das Subir
Published: September 2002

We deal with the interaction between three coplanar Griffith
cracks located symmetrically in the mid plane of an orthotropic
layer of finite thickness 2h. The Fourier transform technique
is used to reduce the elastostatic problem to the solution of a
set of integral equations which have been solved by using the
finite Hilbert transform technique and Cooke′s result. The
analytical expressions for the stress intensity factors at the
crack tips are obtained for large h. Numerical values of the
interaction effect have been computed for and results show that
interaction effects are either shielding or amplification
depending on the location of each crack with respect to each other
and crack tip spacing as well as the thickness of the layer.
Multipliers on L(S), L(S)**, and LUC(S)* for a locally compact topological semigroup
Authors: Medghalchi Alireza
Published: September 2002

We study compact and weakly compact multipliers on
L(S), L(S)**, and LUC(S)*, where the latter is the dual of LUC(S). We show that a left cancellative semigroup S is left amenable if and only if there is a nonzero compact (or weakly compact) multiplier on L(S)**. We also prove that S is left amenable if and only if there is a nonzero compact (or weakly compact) multiplier on LUC(S)*.
Weakly compatible maps in 2‐non‐Archimedean Menger PM‐spaces
Authors: Chugh Renu , Kumar Sanjay
Published: September 2002

The aim of this paper is to introduce the concept of weakly compatible maps in 2‐non‐Archimedean Menger probabilistic metric (PM) spaces and to prove a theorem for these mappings without appeal to continuity. We also provide an application.
On the relation between Moore′s and Penrose′s conditions
Authors: Gan Gaoxiong
Published: September 2002

Moore (1920) defined the reciprocal of any matrix over
the complex field by three conditions, but the beauty of the
definition was not realized until Penrose (1955) defined the same
inverse using four conditions. The reciprocal is now often called
the Moore-Penrose inverse, and has been widely used in
various areas. This note comments on the definitions of
Moore‐Penrose inverse, and gives a new characterization for two
types of weak Moore-Penrose inverses, which exposes an
important relation between Moore′s and Penrose′s
conditions. It also attempts to emphasize the merit of Moore′s
definition, which has been overlooked mainly due to Moore′s
unique notation. Two examples are given to demonstrate some
combined applications of Moore′s and Penrose′s conditions,
including a correction for an incorrect proof of Ben‐Israel′s
(1986) characterization for Moore′s conditions.
Condition R and Fefferman′s mapping theorem
Authors: Darko Patrick
Published: September 2002

It is shown that Fefferman′s mapping theorem extends to the case of manifolds, that is a biholomorphic map between two strictly
pseudoconvex manifolds extends smoothly to their boundaries.
The Galois extensions induced by idempotents in a Galois algebra
Authors: Szeto George , Xue Lianyong
Published: September 2002

Let B be a Galois algebra with Galois group G, Jg = {b ∈ B|bx = g(x)b   for all   x ∈ B} for each g ∈ G, eg the central idempotent such that BJg = Beg, and for a subgroup K of G. Then BeK is a Galois extension with the Galois group
G(eK)( = {g ∈ G | g(eK) = eK}) containing K and the normalizer N(K) of K in G. An equivalence condition is also
given for G(eK) = N(K), and BeG is shown to be a direct sum of
all Bei generated by a minimal idempotent
ei. Moreover, a
characterization for a Galois extension B is shown in terms of
the Galois extension BeG
and B(1 − eG).
On a class of diophantine equations
Authors: Akbik Safwan
Published: September 2002

Cohn (1971) has shown that the only solution in positive
integers of the equation Y(Y + 1)(Y + 2)(Y + 3) = 2X(X + 1)(X + 2)(X + 3) is X = 4, Y = 5. Using this result, Jeyaratnam (1975) has shown that the
equation Y(Y + m)(Y + 2m)(Y + 3m) = 2X(X + m)(X + 2m)(X + 3m) has only four
pairs of nontrivial solutions in integers given by X = 4m or
−7m, Y = 5m or −8m provided that m is of a specified type.
In this paper, we show that if m = (m1, m2) has a specific form
then the nontrivial solutions of the equation Y(Y + m1)(Y + m2)(Y + m1 + m2) = 2X(X + m1)(X + m2)(X + m1 + m2) are m times the primitive solutions of a similar equation with smaller m′s. Then we specifically find all solutions in integers of the
equation in the special case m2 = 3m1.
Fuzzy neighborhood structures on partially ordered groups
Authors: El-Saady Kamel , Bakier M. Y.
Published: September 2002

Ahsanullah (1988) showed the compatibility between group
structures and I‐fuzzy neighborhood systems. In this paper, we
require not only that the I‐fuzzy neighborhood systems be
compatible with the group structures, but also compatible with
the order relation, in one sense or another.
Model tracking for risk problems
Authors: Aggoun Lakhdar , Benkherouf Lakdere
Published: September 2002

We assume that we have M candidate insurance models for
describing a process. The models considered consist of a risk
process driven by right‐constant, finite‐state spaces, jump
processes. Based on observing the history of the risk process,
we propose dynamics whose solutions indicate the likelihoods of
each candidate model.
Some extremal properties of section spaces of Banach bundles and their duals
Authors: Robbins D. A.
Published: September 2002

When X is a compact Hausdorff space and E is a real Banach space there is a considerable literature on extremal properties of
the space C(X, E) of continuous E‐valued functions on X. What
happens if the Banach spaces in which the functions on X take their values vary over X? In this paper, we obtain some extremal
results on the section space Γ(π) and its dual
Γ(π)* of a real Banach bundle π : ℰ → X (with possibly varying fibers), and point out the difficulties in arriving at totally satisfactory results.
Semi‐precontinuous functions and properties of generalized semi‐preclosed sets in topological spaces
Authors: Navalagi G. B.
Published: September 2002

Andrijević (1986) introduced the class of semi‐preopen sets
in topological spaces. Since then many authors including
Andrijević have studied this class of sets by defining their
neighborhoods, separation axioms and functions. The purpose of
this paper is to provide the new characterizations of
semi‐preopen and semi‐preclosed sets by defining the concepts of
semi‐precontinuous mappings, semi‐preopen mappings,
semi‐preclosed mappings, semi‐preirresolute mappings,
pre‐semipreopen mappings, and pre‐semi‐preclosed mappings and
study their characterizations in topological spaces. Recently,
Dontchev (1995) has defined the concepts of generalized
semi‐preclosed (gsp‐closed) sets and generalized semi‐preopen
(gsp‐open) sets in topology. More recently, Cueva (2000)
has defined the concepts like approximately irresolute,
approximately semi‐closed, contra‐irresolute, contra‐semiclosed,
and perfectly contra‐irresolute mappings using
semi‐generalized closed (sg‐closed) sets and semi‐generalized open
(sg‐open) sets due to Bhattacharyya and Lahiri (1987) in
topology. In this paper for gsp‐closed (resp., gsp‐open)
sets, we also introduce and study the concepts of approximately
semi‐preirresolute (ap‐sp‐irresolute) mappings,
approximately semi‐preclosed (ap‐semi‐preclosed) mappings.
Also, we introduce the notions like contra‐semi‐preirresolute,
contra‐semi‐preclosed, and perfectly contra‐semi‐preirresolute
mappings to study the characterizations of semi‐pre‐T1/2 spaces defined by Dontchev (1995).
A note on homomorphisms of Hilbert algebras
Authors: Celani Sergio
Published: September 2002

We give a representation theorem for Hilbert algebras by
means of ordered sets and characterize the homomorphisms of
Hilbert algebras in terms of applications defined between the
sets of all irreducible deductive systems of the associated
algebras. For this purpose we introduce the notion of
order‐ideal in a Hilbert algebra and we prove a separation
theorem. We also define the concept of semi‐homomorphism as
a generalization of the similar notion of Boolean algebras and we
study its relation with the homomorphism and with the
deductive systems.
Mappings of terminal continua
Authors: Charatonik Janusz J.
Published: September 2002

The concept of a terminal continuum introduced in 1973 by G. R. Gordh Jr., for hereditarily unicoherent continua is extended to arbitrary continua. Mapping properties of these two concepts are investigated. Especially the invariance of terminality under mappings satisfying some special conditions is studied. In particular, we conclude that the invariance holds for atomic mappings.
On the concept of optimality interval
Authors: Bibiloni Lluís , Viader Pelegrí , Paradís Jaume
Published: September 2002

The approximants to regular continued fractions constitute
best approximations to the numbers they converge to in two ways known as the first and the second kind. This property of continued fractions provides a solution to Gosper′s problem of the batting average: if the batting average of a baseball player is 0.334, what is the minimum number of times he has been at bat? In this paper, we tackle somehow the inverse question: given a rational number P/Q, what is the set of all numbers for which P/Q is a best approximation of one or the other kind? We prove that in both cases these optimality sets are intervals and we give a precise description of their endpoints.
On the extensions of infinite‐dimensional representations of Lie semigroups
Authors: Mirotin Adolf R.
Published: September 2002

The necessary and sufficient conditions
have been obtained for extendability of a Banach representation of a generating Lie semigroup S to a local representation of the Lie group G generated by S when the tangent wedge of S is a Lie semialgebra. The most convenient conditions we obtain correspond to the case of unitary representations. In this case, we give a
criterion of global extendability if G is exponential and solvable.
Note on decipherability of three‐word codes
Authors: Blanchet-Sadri F. , Howell T.
Published: September 2002

The theory of uniquely decipherable (UD) codes has been widely developed in connection with automata theory, combinatorics on
words, formal languages, and monoid theory. Recently, the
concepts of multiset decipherable (MSD) and set decipherable (SD) codes were developed to handle some special problems in
the transmission of information. Unique decipherability is a
vital requirement in a wide range of coding applications where
distinct sequences of code words carry different information.
However, in several applications, it is necessary or desirable to
communicate a description of a sequence of events where the
information of interest is the set of possible events, including
multiplicity, but where the order of occurrences is irrelevant.
Suitable codes for these communication purposes need not possess
the UD property, but the weaker MSD property. In other applications, the information of interest may be the presence or
absence of possible events. The SD property is adequate for such codes. Lempel (1986) showed that the UD and MSD properties coincide for two‐word codes and conjectured that every three‐word MSD code is a UD code. Guzmán (1995) showed
that the UD, MSD,
and SD properties coincide for two‐word
codes and conjectured that these properties coincide for
three‐word codes. In an earlier paper (2001), Blanchet‐Sadri
answered both conjectures positively for all three‐word codes
{c1, c2, c3} satisfying |c1| = |c2| ≤ |c3|. In this
note, we answer both conjectures positively for other special
three‐word codes. Our procedures are based on techniques related
to dominoes.
Szegő projections for hardy spaces of monogenic functions and applications
Authors: Bernstein Swanhild , Lanzani Loredana
Published: September 2002

We introduce Szegő projections for Hardy spaces of monogenic
functions defined on a bounded domain Ω in ℝn.
We use such projections to obtain explicit orthogonal
decompositions for L2(bΩ). As an application, we obtain an
explicit representation of the solution of the Dirichlet problem
for balls and half spaces with L2, Clifford algebra‐valued,
boundary datum.