2022/09/27 by Magnus B. Landstad, Landstad, Magnus B., Alfons Van Daele +1
Mathematics · #16T05 #20N20 #46L67 #Advanced Operator Algebra Research #Advanced Topics in Algebra #Algebraic structures and combinatorial models #FOS: Mathematics #Group Theory (math.GR) #Quantum Algebra (math.QA)
paper · pdf · doi:10.48550/arxiv.2209.13282
openalex publication_date 2022/09/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
A finite quantum hypergroup is a finite-dimensional unital algebra A over the field of complex numbers. There is a coproduct on A, a coassociative map from A to A⊗ A assumed to be unital, but it is not required to be an algebra homomorphism. There is a counit that is supposed to be a homomorphism. Finally, the main extra requirement is the existence of a faithful left integral with the right properties. For such a finite quantum hypergroup, the dual can be constructed. It is again a finite quantum hypergroup. The more general concept of an algebraic quantum hypergroup is studied in \citeDe-VD1, De-VD2. If the underlying algebra of an algebraic quantum hypergroup is finite-dimensional, it is a finite quantum hypergroup in the sense of this paper. Here we treat finite quantum hypergroups independently with an emphasis on the development of the notion. It is meant to clarify the various steps taken in \citeLa-VD3a and \citeLa-VD3b. In \citeLa-VD3b we introduce and study a still more general concept of quantum hypergroups. It not only contains the algebraic quantum hypergroups from \citeDe-VD1, but also some topological cases. We naturally encounter these quantum hypergroups in our work on bicrossproducts, see \citeLa-VD4, La-VD5, La-VD7. We include some examples to illustrate the theory. One kind is coming from a finite group and a subgroup. The other examples are taken from the bicrossproduct theory.