Browsing Revista Colombiana de Matemáticas by Title
Now showing items 1-20 of 827
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A characterization of primal noetherian rings
Noetherian ring with identity is shown to be a primal ring if and only if the prime ideals are totally ordered by inclusion.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A conjecture concerning the existence of certain combinatorial designs
This note presents a conjecture about the existence of a particular class of combinatorial designs; the consideration of this particular class of designs was suggested during the course of previous work on modular Hadamard ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A correction to my paper: "some topological extensions of plane geometry”
Theorema 4.4 and its proof, in my paper: Some topological extensions of plane geometry. Rev. Colombiana Mat., 1975, IX, 125 - 153, should appear as follows: Let B be a coampact set for wich the interior of Tk (B) contains A.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A counterexample in the theory of linear singularly perturbed systems
In this note we compare the bounded solutions of the linear singularly perturbed system ε X' = A (t) x + f (t), with the solutions of the algebraic system A (t) x + f (t) = 0. Here A and f are bounded C1 functions with ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A deductive calculus for conditional equational systems with built-in predicates as premises
Conditional equationally defined classes of many-sorted algebras, whose premises are conjunctions of (positive) equations and builtin predicates (constraints) in a basic first-order theory, are introduced. These classes ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A duality between hilbert modules and fields of hilbert spaces
The category of Hilbert modules with abelian C*-algebra of scalars and the category of fields of Hilbert spaces over compact Hausdorff spaces are discussed and a duality between them is exhibited.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A first passage problem for three-dimensional diffusion processes
Let d(t) = [Φ(y(t)) + Ψ(z(t))]dt, where y(t) and z(t) are independent diffusion process. The problem of computing the moment generating function and the moments of[T(y, z)], where T(y, z) is a first passage time for (y(t), ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A generalization of fubini's theorem for banach algebra-valued measures
Se demuestra una generalización del teorema deFubini para medidas vectoriales en algebras de Banach, en el caso en que la función a integrar toma también valores en el algebra.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A maximality principle on ordered metric spaces
Se presenta un resultado sobre existencia de elementos maximales en espacios métricos ordenados el cual no requiere para su demostración el lemma de Zorn, basta usar el axioma de selecciones dependientes. Como aplicación ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A method of discretization for the lagerström-cole model equation
A method of discretization for a non linear singularly perturbed boundary value problem is considered. It involves a certain number of steps, one of them including the application of Petrov-Galerkin finite element methods. ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A model of neck formation on a rod under tension
Stability of equilibrium of a circular cylinder under homogeneous axial stretching is investigated in the frame of 3-D nonlinear elasticity. The axisymmetric buckling modes describing developing of a "neck" on the stretched ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A new proof of the Unique Factorization of Z 1 + -d 2 for d = 3, 7, 11, 19, 43, 67, 163
In this paper, we give an elementary proof of the fact that the rings are unique factorization domains for the values d = 3, 7, 11, 19, 43, 67, 163. While the result in itself is well known, our proof is new and completely ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A nonstandard fixed point result in l1 [0,1]
We give a survey on Maurey's contribution to metric fixed point theoryUniversidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on a sequential probability ratio test
This is a type of problema that lies outside the scope of the exponential family.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on generalized mobius (s-functions
In [1] the concept of a conjugate pair of sets of positive integers is introduced. Briefly, if Z denotés the set of positive integers and P and Q denote non-empty subsets of Z such that: if n1 (pertenece a) Z, n2 ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on perfect modules over crossed products
Let R be a ring with identity. We denote the Jacobson radical of R by J(R) and assume throughout that R/J(R) is Arttinian.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on spectral and prespectral operators
Results known for spectral and prespectral operators in weakly complete Banach spaces are extended to Banach spaces with the Bessaga-Pelczynski property.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on the arithmetic of the orthogonal group
The purpose of this paper is to discuss the maximality as a discrete group of the group GZ of all rational integral matrices of the Real Special Orthogonal Group G = SO (H) for all unimodular integrral symmetric n by ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on the asymptotic stability in the whole of non-autonomous systems
In this paper we present some results on the global stability of the trivial solutions x≡ 0 of the system x' = f(t,x). Our main results are then applied to various systems.Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas. -
A note on the controllability of linear first order systems with holomorphic initial functions in elliptic complex numbers
In this paper we characterize the constrained null-controllability of a large family of linear first order systems with holomorphic initial functions in a more general context of holomorphicity given by the elliptic complex ...Universidad Nacional de Colombia Revistas electrónicas UN Revista Colombiana de Matemáticas.