Benjamin Aminof Orna Kupferman Omer Lev On the Relative Succinctness of Nondeterministic Büchi and co-Büchi Word Automata. 183-197 2008 LPAR http://dx.doi.org/10.1007/978-3-540-89439-1_14 conf/lpar/2008 db/conf/lpar/lpar2008.html#AminofKL08