Abstract
Let A be a finite-dimensional algebra over an algebraically closed field k, \(\mathcal{E}\) the category of all exact sequences in A-mod, \(\mathcal{M}_P\) (respectively, \(\mathcal{M}_I\)) the full subcategory of \(\mathcal{E}\) consisting of those objects with projective (respectively, injective) middle terms. It is proved that \(\mathcal{M}_P\) (respectively, \(\mathcal{M}_I\)) is contravariantly finite (respectively, covariantly finite) in ɛ. As an application, it is shown that \(\mathcal{M}_P = \mathcal{M}_I\) is functorially finite and has Auslander-Reiten sequences provided A is selfinjective.
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Song, K., Zhang, Y. Categories of exact sequences with projective middle terms. Sci. China Math. 57, 477–482 (2014). https://doi.org/10.1007/s11425-013-4760-4
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DOI: https://doi.org/10.1007/s11425-013-4760-4
Keywords
- category of exact sequences
- contravariantly finite subcategory
- functorially finite subcategory
- Auslander-Reiten sequences
- selfinjective algebra