Pointed Hopf algebras revisited, with a view from tensor categories

Abstract

Hopf algebras appear in connection with various problems in Pure Mathematics and Theoretical Physics, mainly through their categories of representations, which are examples of tensor categories. In recent years, there have been major advances in the classification of finite-dimensional Hopf algebras over the complex numbers, especially when restricted to the pointed case. In this survey, we aim to review the main results in this direction, stating the classification theorems recently obtained and the problems still open, and describing the tools needed to solve the problem by means of the so-called Lifting Method of Andruskiewitsch and Schneider. We will highlight a more categorical point of view related to these classification results, which offers for a better description of the so-called liftings up to involving cocycle deformations, and which in turn allows certain problems to be reduced to the associated graded pointed Hopf algebras. We will emphasise this point of view with applications to other contexts related to the aforementioned pointed Hopf algebras, such as finite pointed tensor categories, Hopf algebras that do not satisfy the Chevalley property and their finite-dimensional Nichols algebras, and finally module categories over the categories of representations of pointed Hopf algebras.