Formal languages
On measuring nondeterminism in regular languages
Information and Computation
On the relation between ambiguity and nondeterminism in finite automata
Information and Computation
Measures of nondeterminism for pushdown automata
Journal of Computer and System Sciences
ACM SIGACT News
Pushdown automata with bounded nondeterminism and bounded ambiguity
Theoretical Computer Science - Special issue: Latin American theoretical informatics
Context-free languages and pushdown automata
Handbook of formal languages, vol. 1
Grammars with controlled derivations
Handbook of formal languages, vol. 2
Regular Closure of Deterministic Languages
SIAM Journal on Computing
Acta Cybernetica
Introduction To Automata Theory, Languages, And Computation
Introduction To Automata Theory, Languages, And Computation
Regulated Rewriting in Formal Language Theory
Regulated Rewriting in Formal Language Theory
Refining nondeterminism below linear time
Journal of Automata, Languages and Combinatorics - Third international workshop on descriptional complexity of automata, grammars and related structures
Computations with a restricted number of nondeterministic steps.
Computations with a restricted number of nondeterministic steps.
Measuring nondeterminism in pushdown automata
Journal of Computer and System Sciences
One-Turn Regulated Pushdown Automata and Their Reduction
Fundamenta Informaticae
Context-dependent nondeterminism for pushdown automata
Theoretical Computer Science
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A generalization of pushdown automata towards regulated nondeterminism is studied. The nondeterminism is governed in such a way that the decision, whether or not a nondeterministic rule is applied, depends on the whole content of the stack. More precisely, the content of the stack is considered as a word over the stack alphabet, and the pushdown automaton is allowed to act nondeterministically, if this word belongs to some given set R of control words. Otherwise its behavior is deterministic. The computational capacity of such R-PDAs depends on the complexity of R. It turns out that non-context-free languages are accepted even if R is a linear, deterministic context-free language. On the other hand, regular control sets R do not increase the computational capacity of nondeterministic pushdown automata. This raises the natural question for the relations between the structure and complexity of regular sets R on one hand and the computational capacity of the corresponding R-PDA on the other hand. Clearly, if R is empty, the deterministic context-free languages are characterized. For R = {a, b}* one obtains all context-free languages. Furthermore, if R is finite, then the regular closure of the deterministic context-free languages is described. We investigate these questions, and discuss closure properties of the language classes in question under AFL operations.