Pair-splitting, Pair-reaping and Cardinal Invariants of Fσ-ideals
نویسندگان
چکیده
We investigate the pair-splitting number spair which is a variation of splitting number, pair-reaping number rpair which is a variation of reaping number and cardinal invariants of ideals on ω. We also study cardinal invariants of Fσ ideals and their upper bounds and lower bounds. As an application, we answer a question of S. Solecki by showing that the ideal of finitely chromatic graphs is not locally Katětov-minimal among ideals not satisfying Fatou’s lemma.
منابع مشابه
Around splitting and reaping
We prove several results on some cardinal invariants of the continuum which are closely related to either the splitting number s or its dual, the reaping number r.
متن کاملOn Some New Ideals on the Cantor and Baire Spaces
We define and investigate some new ideals of subsets of the Cantor space and the Baire space. We show that combinatorial properties of these ideals can be described by the splitting and reaping cardinal numbers. We show that there exist perfect Luzin sets for these ideals on the Baire space.
متن کاملSerre Subcategories and Local Cohomology Modules with Respect to a Pair of Ideals
This paper is concerned with the relation between local cohomology modules defined by a pair of ideals and the Serre subcategories of the category of modules. We characterize the membership of local cohomology modules in a certain Serre subcategory from lower range or upper range.
متن کاملLocal Cohomology with Respect to a Cohomologically Complete Intersection Pair of Ideals
Let $(R,fm,k)$ be a local Gorenstein ring of dimension $n$. Let $H_{I,J}^i(R)$ be the local cohomology with respect to a pair of ideals $I,J$ and $c$ be the $inf{i|H_{I,J}^i(R)neq0}$. A pair of ideals $I, J$ is called cohomologically complete intersection if $H_{I,J}^i(R)=0$ for all $ineq c$. It is shown that, when $H_{I,J}^i(R)=0$ for all $ineq c$, (i) a minimal injective resolution of $H_{I,...
متن کاملON GRADED LOCAL COHOMOLOGY MODULES DEFINED BY A PAIR OF IDEALS
Let $R = bigoplus_{n in mathbb{N}_{0}} R_{n}$ be a standardgraded ring, $M$ be a finitely generated graded $R$-module and $J$be a homogenous ideal of $R$. In this paper we study the gradedstructure of the $i$-th local cohomology module of $M$ defined by apair of ideals $(R_{+},J)$, i.e. $H^{i}_{R_{+},J}(M)$. Moreprecisely, we discuss finiteness property and vanishing of thegraded components $H^...
متن کامل