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The Larson-Sweedler theorem for multiplier Hopf algebras

Alfons Van Daele·Shuanhong Wang
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Abstract

Any finite-dimensional Hopf algebra has a left and a right integral. Conversely, Larsen and Sweedler showed that, if a finite-dimensional algebra with identity and a comultiplication with counit has a faithful left integral, it has to be a Hopf algebra. In this paper, we generalize this result to possibly infinite-dimensional algebras, with or without identity. We have to leave the setting of Hopf algebras and work with multiplier Hopf algebras. Moreover, whereas in the finite-dimensional case, there is a complete symmetry between the bialgebra and its dual, this is no longer the case in infinite dimensions. Therefore we consider a direct version (with integrals) and a dual version (with cointegrals) of the Larson-Sweedler theorem. We also add some results about the antipode. Furthermore, in the process of this paper, we obtain a new approach to multiplier Hopf algebras with integrals.

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BibTeXRIS

Alfons Van Daele, Shuanhong Wang. 2004-08-17. The Larson-Sweedler theorem for multiplier Hopf algebras. https://arxiv.org/abs/math/0408218

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