Published online by Cambridge University Press: 11 August 2015
From the viewpoint of $C^{\ast }$-dynamical systems, we define a weak version of the Haagerup property for the group action on a
$C^{\ast }$-algebra. We prove that this group action preserves the Haagerup property of
$C^{\ast }$-algebras in the sense of Dong [‘Haagerup property for
$C^{\ast }$-algebras’, J. Math. Anal. Appl.377 (2011), 631–644], that is, the reduced crossed product
$C^{\ast }$-algebra
$A\rtimes _{{\it\alpha},\text{r}}{\rm\Gamma}$ has the Haagerup property with respect to the induced faithful tracial state
$\widetilde{{\it\tau}}$ if
$A$ has the Haagerup property with respect to
${\it\tau}$.