C∗^{*}-bialgebra defined by the direct sum of Cuntz algebras

We show that a tensor product among representation of certain C$^{*}$-algebras induces a bialgebra. Let $\tilde{{\cal O}}_{*}$ be the smallest unitization of the direct sum of Cuntz algebras $${\cal O}_{*}\equiv {\bf C}\oplus {\cal O}_{2}\oplus {\cal O}_{3}\oplus{\cal O}_{4}\oplus ....$$ We show that there exists a non-cocommutative comultiplication $\Delta$ and a counit $\epsilon$ of $\tilde{{\cal O}}_{*}$. From \Delta,\vep and the standard algebraic structure, $\tilde{{\cal O}}_{*}$ is a C$^{*}$-bialgebra. Furthermore we show the following: (i) The antipode on $\tilde{{\cal O}}_{*}$ never exist. (ii) There exists a unique Haar state on $\tilde{{\cal O}}_{*}$. (iii) For a certain one-parameter bialgebra automorphism group of $\tilde{{\cal O}}_{*}$, a KMS state on $\tilde{{\cal O}}_{*}$ exists.Comment: 18 page

Domains of uniqueness for C0C_0-semigroups on the dual of a Banach space

Let $({\cal X},\|\:.\:\|)$ be a Banach space. In general, for a $C_0$-semigroup \semi on $({\cal X},\|\:.\:\|)$, its adjoint semigroup \semia is no longer strongly continuous on the dual space $({\cal X}^{*},\|\:.\:\|^{*})$. Consider on ${\cal X}^{*}$ the topology of uniform convergence on compact subsets of $({\cal X},\|\:.\:\|)$ denoted by ${\cal C}({\cal X}^{*},{\cal X})$, for which the usual semigroups in literature becomes $C_0$-semigroups. The main purpose of this paper is to prove that only a core can be the domain of uniqueness for a $C_0$-semigroup on $({\cal X}^{*},{\cal C}({\cal X}^{*},{\cal X}))$. As application, we show that the generalized Schr\"odinger operator ${\cal A}^Vf={1/2}\Delta f+b\cdot\nabla f-Vf$, $f\in C_0^\infty(\R^d)$, is $L^\infty(\R^d,dx)$-unique. Moreover, we prove the $L^1(\R^d,dx)$-uniqueness of weak solution for the Fokker-Planck equation associated with ${\cal A}^V$