S. Dascalescu

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We study periodic rings that are finitely generated as groups. We prove several structure results. We classify periodic rings that are free of rank at most 2, and also periodic rings R such that R is finitely generated as a group and R/t(R) Z. In this way, we construct new classes of periodic rings. We also ask a question concerning the connection to(More)
We study how the comultiplication on a Hopf algebra can be modified in such a way that the new comultiplication together with the original multiplication and a suitable antipode gives a new Hopf algebra. To this end, we have to study Harrison type cocycles, and it turns out that there is a relation with the Yang-Baxter equation. The construction is applied(More)
Let C = IC(X) be the incidence coalgebra of an intervally finite partially ordered set X over a field. We investigate finiteness properties of C. We determine all C-balanced bilinear forms on C, and we deduce that C is left (or right) quasi-co-Frobenius if and only if C is left (or right) co-Frobenius, and this is equivalent to the order relation on X being(More)
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