Corrections to “Seminormal rings and weakly normal varieties”

Seminormal Rings (following

The Traverso-Swan theorem says that a reduced ring A is seminormal if and only if the natural homomorphism PicA→ PicA[X] is an isomorphism ([18, 17]). We give here all the details needed to understand the elementary constructive proof for this result given by Thierry Coquand in [2]. This example is typical of a new constructive method. The final proof is simpler than the initial classical one. ...

Castelnuovo-Mumford regularity of seminormal simplicial affine semigroup rings

We show that the Eisenbud-Goto conjecture holds for seminormal simplicial affine semigroup rings. Moreover we prove an upper bound for the Castelnuovo-Mumford regularity in terms of the dimension, which is similar as in the normal case. Finally we compute explicitly the regularity of full Veronese rings.

WEAKLY g(x)-CLEAN RINGS

A ring $R$ with identity is called ``clean'' if $~$for every element $ain R$, there exist an idempotent $e$ and a unit $u$ in $R$ such that $a=u+e$. Let $C(R)$ denote the center of a ring $R$ and $g(x)$ be a polynomial in $C(R)[x]$. An element $rin R$ is called ``g(x)-clean'' if $r=u+s$ where $g(s)=0$ and $u$ is a unit of $R$ and, $R$ is $g(x)$-clean if every element is $g(x)$-clean. In this pa...

Weakly left localizable rings

A new class of rings, the class of weakly left localizable rings, is introduced. A ring R is called weakly left localizable if each non-nilpotent element of R is invertible in some left localization SR of the ring R. Explicit criteria are given for a ring to be a weakly left localizable ring provided the ring has only finitely many maximal left denominator sets (eg, this is the case if a ring h...

Skolem Rings and Their Varieties