Published online by Cambridge University Press: 20 November 2018
Given a Bratteli diagram $B$, we study the set
${{\mathcal{O}}_{B}}$ of all possible orderings on
$B$ and its subset
${{\mathcal{P}}_{B}}$ consisting of perfect orderings that produce Bratteli–Vershik topological dynamical systems (Vershik maps). We give necessary and sufficient conditions for the ordering
$\omega $ to be perfect. On the other hand, a wide class of non-simple Bratteli diagrams that do not admit Vershik maps is explicitly described. In the case of finite rank Bratteli diagrams, we show that the existence of perfect orderings with a prescribed number of extreme paths constrains significantly the values of the entries of the incidence matrices and the structure of the diagram
$B$. Our proofs are based on the new notions of skeletons and associated graphs, defined and studied in the paper. For a Bratteli diagram
$B$ of rank
$k$, we endow the set
${{\mathcal{O}}_{B}}$ with product measure
$\mu $ and prove that there is some
$1\,\le \,j\,\le \,k$ such that
$\mu $-almost all orderings on
$B$ have
$j$ maximal and
$j$ minimal paths. If
$j$ is strictly greater than the number of minimal components that
$B$ has, then
$\mu $-almost all orderings are imperfect.