Published online by Cambridge University Press: 01 February 2021
We consider continuous free semigroup actions generated by a family  $(g_y)_{y \,\in \, Y}$ of continuous endomorphisms of a compact metric space
$(g_y)_{y \,\in \, Y}$ of continuous endomorphisms of a compact metric space  $(X,d)$, subject to a random walk
$(X,d)$, subject to a random walk  $\mathbb P_\nu =\nu ^{\mathbb N}$ defined on a shift space
$\mathbb P_\nu =\nu ^{\mathbb N}$ defined on a shift space  $Y^{\mathbb N}$, where
$Y^{\mathbb N}$, where  $(Y, d_Y)$ is a compact metric space with finite upper box dimension and
$(Y, d_Y)$ is a compact metric space with finite upper box dimension and  $\nu $ is a Borel probability measure on Y. With the aim of elucidating the impact of the random walk on the metric mean dimension, we prove a variational principle which relates the metric mean dimension of the semigroup action with the corresponding notions for the associated skew product and the shift map
$\nu $ is a Borel probability measure on Y. With the aim of elucidating the impact of the random walk on the metric mean dimension, we prove a variational principle which relates the metric mean dimension of the semigroup action with the corresponding notions for the associated skew product and the shift map  $\sigma $ on
$\sigma $ on  $Y^{\mathbb {N}}$, and compare them with the upper box dimension of Y. In particular, we obtain exact formulas whenever
$Y^{\mathbb {N}}$, and compare them with the upper box dimension of Y. In particular, we obtain exact formulas whenever  $\nu $ is homogeneous and has full support. We also discuss several examples to enlighten the roles of the homogeneity, of the support and of the upper box dimension of the measure
$\nu $ is homogeneous and has full support. We also discuss several examples to enlighten the roles of the homogeneity, of the support and of the upper box dimension of the measure  $\nu $, and to test the scope of our results.
$\nu $, and to test the scope of our results.
 ${\mathbb{Z}}^p$
-action satisfying expansiveness and specification. Trans. Amer. Math. Soc. 185 (1973), 237–251.CrossRefGoogle Scholar
${\mathbb{Z}}^p$
-action satisfying expansiveness and specification. Trans. Amer. Math. Soc. 185 (1973), 237–251.CrossRefGoogle Scholar