Current volume
Past volumes
1952-1968 Revista de la Unión Matemática Argentina y de la Asociación Física Argentina
1944-1951 Revista de la Unión Matemática Argentina; órgano de la Asociación Física Argentina
1936-1944
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Volumen 54, número 1 (2013)
Published online: June 25, 2013
The N01-matrix completion problem.
Gu-Fang Mou and Ting-Zhu Huang
PDF
An n × n matrix is
called an N01-matrix if all its
principal minors are non-positive and each entry is non-positive.
In this paper, we study general combinatorially symmetric partial
N01-matrix completion problems and
prove that a combinatorially symmetric partial
N01-matrix with all specified off-
diagonal entries negative has an
N01-matrix completion if the graph
of its specified entries is an undirected cycle or a 1-chordal
graph.
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1-14 |
Differentiability and best local approximation.
Héctor H. Cuenya and Claudia N. Rodriguez
PDF
In this paper we give sufficient conditions
over the differentiability of a function to assure existence of
the best local approximant in Lp-spaces,
0 < p ≤ ∞. These conditions are weaker than
those given in previous papers. For p = 2 we show that,
in a certain way, they are also necessary. In addition, we
characterize the best local approximant.
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15-25 |
On mixed brightness-integrals.
Chang-Jian Zhao
PDF
We establish the greatest upper bound for the product of the
i-th brightness-integrals of a convex body and its polar
dual. Further, the greatest upper bound for the product of the
brightness-integrals of order p of a convex body and its
polar dual is also given.
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27-34 |
A combinatorial identity and applications.
Mariano Ferrari and Pablo A. Panzone
PDF
An identity for the finite sum $\sum_1^N\frac{z^n}{q^n-r}$ is given. Related
sums (or series) were studied by Scherk, Clausen, Ramanujan, Shanks, Andrews,
and others. We use such identity to give new formulas for
$\sum_1^\infty\frac{z^n}{q^n-r}$, the Riemann zeta function and the
Euler–Mascheroni constant. An irrationality result is also proved.
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35-42 |
Global controllability of the 1D Schrödinger–Poisson equation.
Mariano De Leo, Constanza Sánchez Fernández de la Vega, and Diego Rial
PDF
This paper is concerned with both the local and global internal controllability
of the 1D Schrödinger–Poisson equation
$iu_t(x,t)=-u_{xx}+V(u)\,u$,
which arises in quantum semiconductor models. Here $V(u)$ is a
Hartree-type nonlinearity stemming from the coupling with the 1D
Poisson equation, which includes the so-called doping profile or
impurities. More precisely, it is shown that for both
attractive and repulsive self-consistent potentials —depending on
the balance between the total charge and the impurities— this
problem is globally internal controllable in a suitable Sobolev space.
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43-54 |
Uniform distribution modulo one of some sequences concerning
the Euler function.
Mehdi Hassani
PDF
In this paper, we follow the recent method in the theory of
uniform distribution, developed by J.-M. Deshouillers and H.
Iwaniec, to prove uniform distribution modulo one of various
sequences involving the Euler function, together with some
generalizations.
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55-68 |
Translations, norm-attaining functionals, and elements of minimum norm.
Francisco Javier García-Pacheco
PDF
In this paper we continue a work that James started in 1971 about
norm-attaining functionals on non-complete normed spaces by
proving that every functional on a normed space is norm-attaining
if and only if every proper, closed, convex subset with non-empty
interior can be translated to have a non-zero, minimum-norm
element. We also study this type of spaces when they are
non-complete. Finally, we consider translations and elements of
maximum norm.
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69-82 |
Maximal operators associated with generalized Hermite polynomial and
function expansions.
Liliana Forzani, Emanuela Sasso, and Roberto Scotto
PDF
We study the weak and strong type boundedness of maximal
heat–diffusion operators associated with the system of
generalized Hermite polynomials and with two different systems of
generalized Hermite functions. We also give a necessary
background to define Sobolev spaces in this context.
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83-107 |
Volumen 54, número 2 (2013)
Published online: December 21, 2013
Sequential entry in one-to-one matching markets.
Beatriz Millán
PDF
We study in one-to-one matching markets a process of sequential
entry, in which participants enter in the market one at a time,
in some arbitrary given order. We identify a large family of
orders (optimal orders) which converge to the optimal stable
matching.
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1-14 |
Metallic structures on Riemannian manifolds.
Cristina-Elena Hreţcanu and Mircea Crasmareanu
PDF
Our aim in this paper is to focus on some
applications in differential geometry of the metallic means
family (a generalization of the golden mean) and generalized
Fibonacci sequences, using a class of polynomial structures
defined on Riemannian manifolds. We search for properties of the
induced structure on a submanifold by metallic Riemannian
structures and we find a necessary and sufficient condition for a
submanifold to be also a metallic Riemannian manifold in terms of
invariance. Also, the totally geodesic, minimal and respectively
totally umbilical hypersurfaces in metallic Riemannian manifolds
are analyzed and the Euclidean space and its hypersphere is
treated as example.
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15-27 |
Multiplication of crowns.
P. J. Witbooi
PDF
It is known that the only finite topological spaces that are
H-spaces are the discrete spaces. For a finite poset which is
weakly equivalent to an H-space, a generalized multiplication may
be found after suitable subdivision. In this paper we construct
minimal models of the k-fold generalised multiplications of
circles in the category of relational structures, including poset
models. In particular, we obtain higher dimensional analogues of
a certain ternary multiplication of crowns [Hardie and Witbooi,
Topology Appl. 154 (2007), no. 10, 2073-2080].
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29-36 |
On Cremona transformations of P3 which factorize in a minimal form.
Ivan Pan
PDF
We consider Cremona transformations of the complex projective
space of dimension 3 which factorize as a product of two
elementary links of type II, without small contractions,
connecting two Fano 3-folds. We show there are essentially eight
classes of such transformations and give a geometric description
of elements in each of these classes.
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37-58 |
On Tauberian conditions for (C, 1) summability of integrals.
Ümit Totur and İbrahim Çanak
PDF
We investigate some Tauberian conditions in terms of the general
control modulo of the oscillatory behavior of integer order of
continuous real functions on [0, ∞) for (C, 1) summability
of integrals. Moreover, we obtain a Tauberian theorem for a real
bounded function on [0, ∞).
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59-65 |
Graph painting and the Borel-de Siebenthal property.
Ching-I Hsin
PDF
In this article, we consider graph painting and introduce the
Borel-de Siebenthal property. We study this property on graphs of type E.
We also study its applications in Hermitian symmetric spaces and hyperbolic
Kac-Moody Lie algebras.
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67-73 |
A historical review of the classifications of Lie algebras.
L. Boza, E. M. Fedriani, J. Núñez, and Á. F. Tenorio
PDF
The problem of Lie algebras’ classification, in their different
varieties, has been dealt with by theory researchers since the
early 20th century. This problem has an intrinsically infinite
nature since it can be inferred from the results obtained that
there are features specific to each field and dimension. Despite
the hundreds of attempts published, there are currently fields
and dimensions in which only partial classifications of some
families of algebras of low dimensions have been obtained. This
article intends to bring some order to the achievements of this
prolific line of research so far, in order to facilitate future
research.
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75-99 |
On connectedness via a sequential method.
Hüseyin Çakallı and Osman Mucuk
PDF
Recently, the first author has introduced a concept of
G-sequential connectedness in the sense that a non-empty
subset A of a Hausdorff topological group X is
G-sequentially connected if the only subsets of A
which are both G-sequentially open and
G-sequentially closed are A and the empty set ∅.
In this paper we investigate further properties of
G-sequential connectedness and obtain some interesting
results.
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101-109 |
Two classes of slant surfaces in the nearly Kähler six sphere.
K. Obrenović and S. Vukmirović
PDF
In this paper we find examples of slant surfaces in the nearly
Kähler six sphere. First, we characterize two-dimensional small
and great spheres which are slant. Their description is given in
terms of the associative 3-form in Im O. Later on, we
classify the slant surfaces of S6 which are
orbits of a maximal torus in G2. Among them we
find a one parameter family of minimal orbits with arbitrary
slant angle.
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111-121 |
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