Invariant means on subspaces of quantum weakly almost periodic functionals

Abstract: Let $M$ be a Hopf--von Neuman algebra with the predual $M_$ and $WAP(M)$ the subspace in $M$ composed of weakly almost periodic functionals on $M_$. The main example of such an algebra is $M=L^\infty(\mathbb G)$ for a locally compact quantum group $\mathbb G$. We define a pair of left/right spaces $WAP_{iso,l}(M)$ and $WAP_{iso,r}(M)$ inside $WAP(M)$ and prove that they carry invariant means. These spaces are currently the widest known to admit invariant means in the quantum setting. In the case when $M=L^\infty(G)$ and $G$ is a locally compact group, these spaces are equal to $WAP(G)$.