Collectanea Mathematica ( IF 1.1 ) Pub Date : 2020-08-09 , DOI: 10.1007/s13348-020-00298-y Kamal Bahmanpour
Let I be an ideal of a commutative Noetherian ring R. It is shown that the R-modules \(H^i_I(M)\) are I-cofinite, for all finitely generated R-modules M and all \(i\in {\mathbb {N}}_0\), if and only if the R-modules \(H^i_I(R)\) are I-cofinite with dimension not exceeding 1, for all integers \(i\ge 2\); in addition, under these equivalent conditions it is shown that, for each minimal prime ideal \({{\mathfrak {p}}}\) over I, either \({{\text {height}}}{{\mathfrak {p}}}\le 1\) or \(\dim R/{{\mathfrak {p}}}\le 1\), and the prime spectrum of the I-transform R-algebra \(D_I(R)\) equipped with its Zariski topology is Noetherian. Also, by constructing an example we show that under the same equivalent conditions in general the ring \(D_I(R)\) need not be Noetherian. Furthermore, in the case that R is a local ring, it is shown that the R-modules \(H^i_I(M)\) are I-cofinite, for all finitely generated R-modules M and all \(i\in {\mathbb {N}}_0\), if and only if for each minimal prime ideal \({\mathfrak {P}}\) of \({\widehat{R}}\), either \(\dim {\widehat{R}}/(I{\widehat{R}}+{\mathfrak {P}})\le 1\) or \(H^i_{I{\widehat{R}}}({\widehat{R}}/{\mathfrak {P}})=0\), for all integers \(i\ge 2\). Finally, it is shown that if R is a semi-local ring and the R-modules \(H^i_I(M)\) are I-cofinite, for all finitely generated R-modules M and all \(i\in {\mathbb {N}}_0\), then the category of all I-cofinite modules forms an Abelian subcategory of the category of all R-modules.
中文翻译:
关于哈兹霍恩的问题
让我成为交换Noether环R的理想选择。对于所有有限生成的R模块M和所有\ {i \ in {\ mathbb {N}} _ 0 \)来说,表明R-模块\(H ^ i_I(M)\)是I-有限的,如果对于所有整数\(i \ ge 2 \),并且仅当R -modules \(H ^ i_I(R)\)为I-整数且维数不超过1时;另外,这些等同的条件下,示出了,对于每一个最小素理想\({{\ mathfrak {P}}} \)超过予,无论是\({{\ text {height}}} {{\ mathfrak {p}}} \ le 1 \)或\(\ dim R / {{\ mathfrak {p}}} \ le 1 \)以及素数的频谱中的我-transform ř代数\(D_I(R)\)配备有其Zariski拓扑是诺特。而且,通过构造一个示例,我们表明在相同的等效条件下,环\(D_I(R)\)通常不需要为Noetherian。此外,在R是局部环的情况下,对于所有有限生成的R模块M和所有\(i \ in ),表明R-模块\(H ^ i_I(M)\)是I- cofinite 。 {\ mathbb {N}} _ 0 \),当且仅当对于每个最小素理想\({\ mathfrak {P}} \)的\({\ widehat {R}} \),无论是\(\暗淡{\ widehat {R}} /(I { \ widehat {R}} + {\ mathfrak {P}})\ le 1 \)或\(H ^ i_ {I {\ widehat {R}}}({\ widehat {R}} / {\ mathfrak {P }} = 0 = 0),所有整数\(i \ ge 2 \)。最后,表明,对于所有有限生成的R模块M和所有\(i \ in {,,如果R是一个半局部环并且R-模块\(H ^ i_I(M)\)是I-有限的, \ mathbb {N}} _ 0 \),然后是所有我的类别-cofinite模块形成所有R -modules类别的Abelian子类别。