Theory of recursive functions and effective computability
Theory of recursive functions and effective computability
The complexity of computing the number of strings of given length in context-free languages
Theoretical Computer Science
A quasi-polynomial-time algorithm for sampling words from a context-free language
Information and Computation
Handbook of formal languages, vol. 1
The unsolvability of the Equivalence Problem for Λ-Free nondeterministic generalized machines
Journal of the ACM (JACM)
Unusual algorithms for lexicographical enumeration
Acta Cybernetica
Simulating finite automata with context-free grammars
Information Processing Letters
On the number of distinct languages accepted by finite automata with n states
Journal of Automata, Languages and Combinatorics - Third international workshop on descriptional complexity of automata, grammars and related structures
The degree hierarchy of undecidable problems of formal grammars
STOC '70 Proceedings of the second annual ACM symposium on Theory of computing
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
Enumerating regular expressions and their languages
CIAA'04 Proceedings of the 9th international conference on Implementation and Application of Automata
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In this paper, we consider the enumeration of context-free languages. In particular, for any reasonable descriptional complexity measure for context-free grammars, we demonstrate that the exact number of context-free languages of size n is uncomputable. Nevertheless, we are able to give upper and lower bounds on the number of such languages. We also generalize our uncomputability results to a general theorem applicable to enumeration of equivalence classes or yes-instances of predicates.