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Pascual Jara

Publications and source records attributed to Pascual Jara.

11 recordsLinked to original sources
arXiv2021

Gradual and fuzzy subsets

In fuzzy theory of sets and groups, the use of $α$--levels is a standard to translate problems from the fuzzy to the crisp framework. Using strong $α$--levels, it is possible to establish a one to one correspondence which makes possible doubly, a gradual and a functorial treatment of the fuzzy theory. The main result of this paper is to identify the class of fuzzy sets, respectively fuzzy groups, with subcategories of the functorial categories $\mathcal{S}\textit{et}^{(0,1]}$, resp. $\mathcal{G}\textit{r}^{(0,1]}$.

math.LO↗
arXiv2021

Lattice decomposition of modules

The first aim of this work is to characterize when the lattice of all submodules of a module is a direct product of two lattices. In particular, which decompositions of a module $M$ produce these decompositions: the \emph{lattice decompositions}. In a first \textit{étage} this can be done using endomorphisms of $M$, which produce a decomposition of the ring $\textrm{End}_R(M)$ as a product of rings, i.e., they are central idempotent endomorphisms. But since not every central idempotent endomorphism produces a lattice decomposition, the classical theory is not of application. In a second step we characterize when a particular module $M$ has a lattice decomposition; this can be done, in the commutative case in a simple way using the support, $\textrm{Supp}(M)$, of $M$; but, in general, it is not so easy. Once we know when a module decomposes, we look for characterizing its decompositions. We show that a good framework for this study, and its generalizations, could be provided by the category $σ[M]$, the smallest Grothendieck subcategory of $\textbf{Mod}-{R}$ containing $M$.

math.RA↗
arXiv2020

An extension of $S$-noetherian rings and modules

For any commutative ring $A$ we introduce a generalization of $S$-noetherian rings using a hereditary torsion theory $σ$ instead of a multiplicatively closed subset $S\subseteq{A}$. It is proved that if $A$ is a totally $σ$-noetherian ring, then $σ$ is of finite type, and that totally $σ$-noetherian is a local property.

math.AC↗
arXiv2009

On the classification of twisting maps between $K^n$ and $K^m$

We define the notion of admissible pair for an algebra $A$, consisting on a couple $(Γ,R)$, where $Γ$ is a quiver and $R$ a unital, splitted and factorizable representation of $Γ$, and prove that the set of admissible pairs for $A$ is in one to one correspondence with the points of the variety of twisting maps $\mathcal{T}_A^n:=\mathcal{T}(K^n,A)$. We describe all these representations in the case $A=K^m$.

math.RA↗
arXiv2009

Multivariate interpolation

The aim of this work is to show how symbolic computation can be used to perform multivariate Lagrange, Hermite and Birkhoff interpolation and help us to build more realistic interpolating functions. After a theoretical introduction in which we analyze the complexity of the method we shall focus our attention on applications.

math.NA↗
arXiv2008

Prime path coalgebras

We use prime coalgebras as a generalization of simple coalgebras, and observe that prime subcoalgebras represent the structure of the coalgebra in a more efficient way than simple coalgebras. In particular, in this work we focus our attention on the study and characterization of prime subcoalgebras of path coalgebras of quivers and, by extension, of prime pointed coalgebras.

math.RA↗
arXiv2007

Localization in tame and wild coalgebras

We apply the theory of localization for tame and wild coalgebras in order to prove the following theorem: "Let Q be an acyclic quiver. Then any tame admissible subcoalgebra of KQ is the path coalgebra of a quiver with relations".

math.RT↗
arXiv2003

Lie bracket of vector fields in noncommutative geometry

The aim of this paper is to avoid some difficulties, related with the Lie bracket, in the definition of vector fields in a non commutative setting, as they were defined by Woronowicz, Schmudgen--Schuler and Aschieri--Schupp. We extend the definition of vector fields to consider them as derivations of the algebra, through Cartan pairs introduced by Borowiec. Then, using translations, we introduce the invariant vector fields. Finally, the definition of Lie bracket realized by Dubois--Violette, considering elements in the center of the algebra, is also extended to these invariant vector fields.

math.RA↗
arXiv2003

Local--Global Properties for Semistar Operations

We study the "local" behavior of several relevant properties concerning semistar operations, like finite type, stable, spectral, e.a.b. and a.b. We deal with the "global" problem of building a new semistar operation on a given integral domain, by "gluing" a given homogeneous family of semistar operations defined on a set of localizations. We apply these results for studying the local--global behavior of the semistar Nagata ring and the semistar Kronecker function ring. We prove that an integral domain $D$ is a Pr{ü}fer $\star$--multiplication domain if and only if all its localizations $D_{P}$ are Pr{ü}fer $\star_P$--multiplication domains.

math.AC↗
arXiv2002

Prüfer $\star$--multiplication domains and semistar operations

We prove a characterization of a P$\star$MD, when $\star$ is a semistar operation, in terms of polynomials (by using the classical characterization of Prüfer domains, in terms of polynomials given by R. Gilmer and J. Hoffman \cite{Gilmer/Hoffmann:1974}, as a model), extending a result proved in the star case by E. Houston, S.J. Malik and J. Mott \cite{Houston/Malik/Mott:1984}. We also deal with the preservation of the P$\star$MD property by ``ascent'' and ``descent'' in case of field extensions. In this context, we generalize to the P$\star$MD case some classical results concerning Prüfer domains and P$v$MDs. In particular, we reobtain as a particular case a result due to H. Prüfer \cite{Prufer} and W. Krull \cite{Krull:1936} (cf. also F. Lucius \cite{Lucius:1998} and F. Halter-Koch \cite{Koch:2000}). Finally, we develop several examples and applications when $\star$ is a (semi)star given explicitly (e.g. we consider the case of the ``standard'' $v$--, $t$--, $b$--, $w$--operations or the case of semistar operations associated to appropriate families of overrings).

math.AC↗