Tame or wild Toeplitz shifts

Abstract

We investigate tameness of Toeplitz shifts. By introducing the notion of extended Bratteli-Vershik diagrams, we show that such shifts with finite Toeplitz rank are tame if and only if there are at most countably many orbits of singular fibres over the maximal equicontinuous factor. The ideas are illustrated using the class of substitution subshifts. A body of elaborate examples shows that the assumptions of our results cannot be relaxed.