A pumping lemma for deterministic context-free languages
Information Processing Letters
Measures of nondeterminism for pushdown automata
Journal of Computer and System Sciences
A New Approach to Formal Language Theory by Kolmogorov Complexity
SIAM Journal on Computing
Pushdown automata with bounded nondeterminism and bounded ambiguity
Theoretical Computer Science - Special issue: Latin American theoretical informatics
Introduction to Formal Language Theory
Introduction to Formal Language Theory
Measuring nondeterminism in pushdown automata
Journal of Computer and System Sciences
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
Introduction to Automata Theory, Languages, and Computation (3rd Edition)
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By explicit nondeterminism degree of a pushdown automata we mean the maximal number of choices in the transitions of the automata. In this paper we will prove that each pushdown automaton has an equivalent pushdown automaton with degree 1 of explicit nondeterminism, which implies that λ-moves in pda are sufficient to simulate nondeterminism. Moreover, from this normal form (i.e. pda with degree 1 of explicit nondeterminism) we can measure the amount of (implicit) nondeterminism. This measure will be used to determine a countable infinite hierarchy of contextfree language subclasses, whose bottom is the class of deterministic context-free languages and the top is the class of context-free languages.