2021/09/17 by Byung-Jay Kahng, Kahng, Byung-Jay
Mathematics · #Advanced Operator Algebra Research #Advanced Topics in Algebra #Algebraic structures and combinatorial models #FOS: Mathematics #Operator Algebras (math.OA) #Quantum Algebra (math.QA)
paper · pdf · doi:10.48550/arxiv.2109.08803
openalex publication_date 2021/09/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Van Daele and Wang developed a purely algebraic notion of weak multiplier Hopf algebras, which extends the notions of Hopf algebras, multiplier Hopf algebras, and weak Hopf algebras. With an additional requirement of an existence of left or right integrals, this framework provides a self-dual class of algebraic quantum groupoids. The aim of this paper is to show that from this purely algebraic data, with only some relatively minimal additional requirements (``quasi-invariance''), one can construct a C^*-algebraic quantum groupoid of separable type, recently defined by the author with Van Daele. The C^*-algebraic quantum groupoid is represented as an operator algebra on the Hilbert space constructed from the left integral, and the comultiplication is determined by means of a certain multiplicative partial isometry W, which is no longer unitary. In the last section (Appendix), we obtain some results in the purely algebraic setting, which have not appeared elsewhere.