时　间：11月13日（周三）下午4: 00-5：00

地　点：数学楼102

报告人：陈红星（副教授）首都师范大学

摘　要： A new homological dimension, called rigidity dimension, is introduced to measure the quality of resolutions of finite dimensional algebras (especially of infinite global dimension) by algebras of finite global dimension and big dominant dimension. Upper bounds of this dimension are established in terms of extensions and of Hochschild cohomology. In particular, the rigidity dimension of a non-semisimple group algebra is finite and bounded by the order of the group. Then invariance under stable equivalences is shown to hold, with some exceptions when there are nodes in case of additive equivalences, and without exceptions in case of triangulated equivalences. Stable equivalences of Morita type and derived equivalences, both between self-injective algebras, are shown to preserve rigidity dimension as well. Finally, rigidity dimensions of classes of examples will be determined. This is a joint work with Ming Fang, Otto Kerner, Steffen Koenig and Kunio Yamagata.