We know that DCFL is not closed under the union operation and CFL is closed under union and contains the union of DCFLs.
Is there a characterization of finite unions of DCFLs?
Theoretical Computer Science Stack Exchange is a question and answer site for theoretical computer scientists and researchers in related fields. It only takes a minute to sign up.Sign up to join this community
One direction is clear: the union of any finite number of DCFL's is a CFL.
However, a precise characterization of the union-closure of DCFL's was not obvious to me at all (and I teach this stuff and wrote a book on it), so I went searching with a google search. I found this paper by my colleagues Martin Kutrib and Andreas Malcher: Context-Dependent Nondeterminism for Pushdown Automata, O.H. Ibarra and Z. Dang (Eds.): DLT 2006, LNCS 4036, pp. 133–144, 2006. Theorem 1 gives a characterization of this class.