  We consider the representational state complexity of unranked tree automata.
The bottom-up computation of an unranked tree automaton may be either
deterministic or nondeterministic, and further variants arise depending on
whether the horizontal string languages defining the transitions are
represented by a DFA or an NFA. Also, we consider for unranked tree automata
the alternative syntactic definition of determinism introduced by Cristau et
al. (FCT'05, Lect. Notes Comput. Sci. 3623, pp. 68-79).
  We establish upper and lower bounds for the state complexity of conversions
between different types of unranked tree automata.
