Density Functional Calculations on Homonuclear Polysulfur Ring Molecules,S5-S16

The density functional method, B3PW91, using the 6–311+G(3df) basis function set from the Gaussian 98 collection of programs, was used to successfully reproduce the experimental structure parameters of polysulfur ring molecules, S₆ – S₁₄. Structural predictions of S₅, S₁₅, and S₁₆ are also given. The relative electronic energies are also compared.     

逆M-矩阵在Hadamard积下的封闭性

一般的n阶逆M 矩阵类在Hadamard积下是不封闭性 ,本文主要研究逆M 矩阵的一些重要子类在Hadamard积下封闭性 ,并证明 :对n阶的三对角线逆M 矩阵类 ;对其中一个为上 ,一个为下Hessenburg的逆M 矩阵类 ;有唯一路有向图的M 矩阵类的逆在Hadamard积下是封闭的 ,同时给出了逆M 矩阵的几个重要性质     

Auslander-Reiten Triangles, Ziegler Spectra and Gorenstein Rings

We investigate (existence of) Auslander—Reiten triangles in a triangulated category in connection with torsion pairs, existence of Serre functors, representability of homological functors and realizability of injective modules. We also develop an Auslander—Reiten theory in a compactly generated triangulated category and we study the connections with the naturally associated Ziegler spectrum. Our analysis is based on the relative homological theory of purity and Brown's Representability Theorem. Our main interest lies in the structure of Auslander—Reiten triangles in the full subcategory of compact objects. We also study the connections and the interplay between Auslander—Reiten theory, pure-semisimplicity and the finite type property, Grothendieck groups, and we give applications to derived categories of Gorenstein rings.     

Images and Open Subspaces of SV Spaces

A topological space is finitely an F-space if its Stone–?ech compactification is a union of finitely many closed F-spaces and a space is SV if C(X) has the property that C(X)/P is a valuation domain for each prime ring ideal P of C(X). This article studies the images under open continuous functions and the open subspaces of spaces that are finitely an F-space or are SV. It is shown that an open continuous image of a compact space that is finitely an F-space is finitely an F-space and an open continuous image of certain SV spaces is SV. Also, it is shown cozerosets, but not necessarily open sets, of SV spaces are SV spaces and a similar situation holds for spaces that are finitely an F-space.     

Perfect Rings: A Local Approach

We analyze how the left perfect condition on a ring A (not necessarily with identity) relates to the left perfect condition on unital subrings of the form eAe (where e is idempotent). We then use this analysis to examine a class of graded left perfect rings.     

Rings of Constants of the Form k[f]

Let k[X] be the algebra of polynomials in n variables over a field k of characteristic zero, and let f ? k[X]? k. We present a construction of a derivation d of k[X] whose ring of constants is equal to the integral closure of k[f] in k[X]. A similar construction for fields of rational functions is also given.     

Rings of Continuous Functions on Spaces of Finite Rank and the SV Property

Let X be a compact topological space and let C(X) denote the f-ring of all continuous real-valued functions defined on X. A point x in X is said to have rank n if, in C(X), there are n minimal prime ?-ideals contained in the maximal ?-ideal M _x  = {f ? C(X):f(x) = 0}. The space X has finite rank if there is an n ? N such that every point x ? X has rank at most n. We call X an SV space (for survaluation space) if C(X)/P is a valuation domain for each minimal prime ideal P of C(X). Every compact SV space has finite rank. For a bounded continuous function h defined on a cozeroset U of X, we say there is an h-rift at the point z if h cannot be extended continuously to U ∪ {z}. We use sets of points with h-rift to investigate spaces of finite rank and SV spaces. We show that the set of points with h-rift is a subset of the set of points of rank greater than 1 and that whether or not a compact space of finite rank is SV depends on a characteristic of the closure of the set of points with h-rift for each such h. If X has finite rank and the set of points with h-rift is an F-space for each h, then X is an SV space. Moreover, if every x ? X has rank at most 2, then X is an SV space if and only if for each h, the set of points with h-rift is an F-space.     

Two-Sided Localization of Bimodules

We extend to bimodules Schelter's localization of a ring with respect to Gabriel filters of left and right ideals. Our two-sided localization of bimodules provides an endofunctor on a convenient bicategory of rings with filters of ideals. This is used to study the Picard group of a ring relative to a filter of ideals.     

Standardly stratified lower triangular K-algebras with enough idempotents

In this paper we study the lower triangular matrix $\mathbb{K}$-algebra $\mathrm{\Lambda }:=\left[\begin{array}{cc}\hfill T\hfill & \hfill 0\hfill \\ \hfill M\hfill & \hfill U\hfill \end{array}\right]$, where U and T are basic $\mathbb{K}$-algebras with enough idempotents and M is an U-T-bimodule where $\mathbb{K}$ acts centrally. Moreover, we characterise in terms of U, T and M when, on one hand, the lower triangular matrix $\mathbb{K}$-algebra Λ is standardly stratified in the sense of [15]; and on the other hand, when Λ is locally bounded in the sense of Gabriel [10]. Finally, we also study several properties relating the projective dimensions in the categories of finitely generated modules $\mathrm{mod}(U)$, $\mathrm{mod}(T)$ and $\mathrm{mod}(\mathrm{\Lambda })$.