Revistas académicas de la Universidad Católica del Norte
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Global smoothness preservation by singular integrals
No full textHere is established that the well-known singular integrals of Picard, Poisson-Cauchy and Gauss- Weierstrass fulfill the "global smoothness preservation" property. J. e., they "ripple" less than the function they are applied on, that is producing a nice approximation to the unit. The associated inequalities are sharp
On the spectrum of the conjugation action for Dn
No full textWe prove the conjeture of [2] for the dihedral group Dn, i. e. the spectrum of the natural representation associed to the action by conjugation of Dn over itself, provides all isomorphy types of projective group of Dn (see Theorem 1)
Isochronous oscillations for cubic systems
No full textPlanar vector fields? = -y + P?(x,y)? = x + q?(x, y).with a center non necessarily at the origin are considered, where p? and q? are homogeneous polynomials of degree 3. We are concerned with the behavior of the periods of the periodic solutions near the center, and in determining when the center is isochronous, i.e., when all periodic solutions have the same period. It is proved that, modulus a linear change of coordinates, there are only four systems which have an isochronous center. Each of them has an isochronous center at the origin, and its other centers are also isochronous but not necessarily with the same period. Also the maximal weakness of the non isochronous centers, is obtained
Characterizations of 0-submodules
No full textIn this paper we give an introduction to prime submodules in order to generalize the concept of prime ideal to the category of modules. First of all, we study prime submodules of ideal 0 in the case where the ring is an integral domain. For this reason we ha ve called these submodules 0 submodules. We show several properties of these submodules are torsion free. This result allows us to apply local cohomology to characterize 0- submodules of rank one of reflexive modules over the polynomial ring in n variables as free modules. Second, we develop two theorems which define a bijection between objects
On euclidean rings
No full textIn this article we extend the concept of Euclidean rings and Motzkin's work to commutative rings (not necessarily with an identity)
Une inégalité optimale pour des sous-variétés riemanniennes dans des espaces pseudo-Riemanniens
No full textOptimality of the trace of a product of matrices
No full textA simple and short proof of the optimality conditions in the John von Neumann trace inequality for singular values is shown. Possible generalizations and special cases are also considered
Asymptotic behavior of the weighted trace of Schrodinger equation with operator coefficient given in n-dimensional space
No full textWe show that an operator formed by Schrodinger differential expression with operator coefficient on separable Hilbert space has a pure discrete spectrum. We also discuss the asymptotic behavior of the weighted trace of this operator
On velocity bimagnetic biharmonic particles with energy on Heisenberg space
No full textIn this work, we consider velocity bimagnetic biharmonic particle on 3D Heisenberg space in the magnetic field B and we give the concept of energy. Moreover, we characterize energy conditions of velocity bimagnetic biharmonic particles with Frenet vector field. Therefore, we obtain energy results for bimagnetic particles by Frenet fields in the Heisenberg space
On rough convergence of triple sequence spaces of Bernstein-Stancu operators of fuzzy numbers defined by a metric function
No full textWe define the concept of rough limit set of a triple sequence space of Bernstein-Stancu polynomials of fuzzy numbers and obtain the relation between the set of rough limit and the extreme limit points of a triple sequence space of Bernstein-Stancu polynomials of fuzzy numbers. Finally, we investigate some properties of the rough limit set of Bernstein-Stancu polynomials