We fix the standard inner products on $\mathbb{C}^n$ and $\mathbb{C}^n\otimes \mathbb{C}^n$.
Is there an anlgebraalgebra structure on $\mathbb{C}^n$ with multiplication $m$ such that the adjoint operator $m^*: \mathbb{C}^n \to \mathbb{C}^n \otimes \mathbb{C}^n$ is a coproduct (Coalgebraiccoalgebraic operation)?
Is there a bialgebra structure whose product and coproduct are adjointadjoints of each other? Is there a Hopf algebra with the laterlatter property, and the additional condition that the antipodantipode map is an isometry?
Note: Note that theThe adjoint operatoresoperators are taken associatedwith respect to the corresponding inner products.