A counterexample to Raikov's conjecture

被引:28
作者
Rump, Wolfgang [1 ]
机构
[1] Univ Stuttgart, Inst Algebra & Number Theory, D-70550 Stuttgart, Germany
关键词
D O I
10.1112/blms/bdn080
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
Quasi-abelian categories are additive categories for which the class of all short exact sequences defines an exact structure. Such categories are ubiquitous and form a natural framework for relative homological algebra and K-theory. Higher Ext-groups also exist in categories with the formally weaker property to be semi-abelian. Raikov's conjecture states that both concepts are equivalent. We use a tilted algebra of type (6) to construct a counterexample.
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页码:985 / 994
页数:10
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