@article{Tan2022, 
author = {Lingling Tan and Tiwei Zhao},
title = {Extension-closed subcategories in extriangulated categories},
year = {2022},
journal = {AIMS Mathematics},
volume = {7},
number = {5},
pages = {8250-8262},
keywords = {extriangulated categories, extension-closed subcategories, almost split morphism, negative first extension, exact categories},
url = {https://www.sciopen.com/article/10.3934/math.2022460},
doi = {10.3934/math.2022460},
abstract = {In this paper, we mainly focus on extension-closed subcategories of extriangulated categories. Let              X       be an extension-closed subcategory. We show that if    C is              X      -projective and there is a minimal right almost split deflation in              X       ending by    C, then there is an              s      -triangle ending by    C which is very similar to an Auslander-Reiten triangle in              X      . We also show that if the extriangulated category admits a negative first extension                      E                    −      1      , and              X       is self-orthogonal with respect to                      E                    −      1      , then              X       has an exact structure.}
}