Published online by Cambridge University Press: 11 November 2015
We prove that if $G_{P}$ is a finitely constrained group of binary rooted tree automorphisms (a group binary tree subshift of finite type) defined by an essential pattern group
$P$ of pattern size
$d$,
$d\geq 2$, and if
$G_{P}$ has maximal Hausdorff dimension (equal to
$1-1/2^{d-1}$), then
$G_{P}$ is not topologically finitely generated. We describe precisely all essential pattern groups
$P$ that yield finitely constrained groups with maximal Hausdorff dimension. For a given size
$d$,
$d\geq 2$, there are exactly
$2^{d-1}$ such pattern groups and they are all maximal in the group of automorphisms of the finite rooted regular tree of depth
$d$.