Erratum to: "C(X) vs. C(X) modulo its socle" (Colloq. Math. 111 (2008), 315-336)
2000 Mathematics Subject Classification: 16N80, 16S70, 16D25, 13G05.We construct some new examples showing that Heyman and Roos construction of the essential closure in the class of associative rings can terminate at any finite or the first infinite ordinal.
In this note we show that for a -module, in particular, an almost -tilting module, over a ring with such that has finite flat dimension, the upper bound of the global dimension of can be estimated by the global dimension of and hence generalize the corresponding results in tilting theory and the ones in the theory of -modules. As an application, we show that for a finitely generated projective module over a VN regular ring , the global dimension of its endomorphism ring is not more...
We determine the length of composition series of projective modules of G-transitive algebras with an Auslander-Reiten component of Euclidean tree class. We thereby correct and generalize a result of Farnsteiner [Math. Nachr. 202 (1999)]. Furthermore we show that modules with certain length of composition series are periodic. We apply these results to G-transitive blocks of the universal enveloping algebras of restricted p-Lie algebras and prove that G-transitive principal blocks only allow components...
By using the interplay between the Eulerian idempotent and the Dynkin idempotent, we construct explicitly a particular symmetric solution of the first equation of the Kashiwara-Vergne conjectureThen, we explicit all the solutions of the equation in the completion of the free Lie algebra generated by two indeterminates and thanks to the kernel of the Dynkin idempotent.
To a commutative ring K, and a family of K-algebras indexed by the vertex set of a graph, we associate a K-algebra obtained by a mixture of coproduct and tensor product constructions. For this, and related constructions, we give exact sequences and deduce homological properties.