In this paper, we first introduce a lower bound technique for the
state complexity of transformations of automata. Namely we suggest
first considering the class of full automata in lower bound analysis,
and later reducing the size of the large alphabet via alphabet substitutions.
Then we apply such technique to the complementation of nondeterministic
ω-automata, and obtain several lower bound results. Particularly,
we prove an Ω((0.76n)n) lower bound for Büchi complementation,
which also holds for almost every complementation or determinization
transformation of nondeterministic ω-automata, and prove an
optimal (Ω(nk))n lower bound for the complementation of
generalized Büchi automata, which holds for Streett automata as
well.