Positive Herz-Schur multipliers and approximation properties of crossed products

Andrew McKee, Adam Skalski, Ivan G. Todorov +1

For a $C^{\ast }$-algebra $A$ and a set $X$ we give a Stinespring-type characterisation of the completely positive Schur $A$-multipliers on $K({\ell }^2(X))\otimes A$. We then relate them t…