  In this paper we further develop the theory of one sided shift spaces over
infinite alphabets, characterizing one-step shifts as edge shifts of
ultragraphs and partially answering a conjecture regarding shifts of finite
type (we show that there exists shifts of finite type that are not conjugate,
via a conjugacy that is eventually finite periodic, to an edge shift of a graph
). We also show that there exists edge shifts of ultragraphs that are shifts of
finite type, but are not conjugate to a full shift, a result that is not true
for edge shifts of graphs. One of the key results needed in the proofs of our
conclusions is the realization of a class of ultragraph C*-algebras as partial
crossed products, a result of interest on its own.
