We put a non-trivial comultiplication on the natural tensor product algebra of two multiplier Hopf algebras by means of a "cotwisting map." As a special case we characterize the dual of the Drinfel'd double of an algebraic quantum group. Because any finite-dimensional Hopf algebra is an algebraic quantum group, our characterization applies to the dual of the Drinfel'd double of a finite-dimensional Hopf algebra. Then it coincides with a result of Lu. © 2004 Elsevier Inc. All rights reserved.
Delvaux, L. (2004). Twisted tensor coproduct of multiplier Hopf algebras. Journal of Algebra, 274(2), 751–771. https://doi.org/10.1016/j.jalgebra.2003.09.006