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- Publications
- Influence

Conjunctive Grammars

- A. Okhotin
- Computer Science, Mathematics
- J. Autom. Lang. Comb.
- 1 April 2001

This paper introduces a class of formal grammars made up by augmenting the formalism of context-free grammars with an explicit set-theoretic intersection operation. It is shown that conjunctive… Expand

On the State Complexity of Scattered Substrings and Superstrings

- A. Okhotin
- Computer Science, Mathematics
- Fundam. Informaticae
- 1 August 2010

It is proved that the set of scattered substrings of a language recognized by an n-state DFA requires a DFA with at least 2$^{n/2-2}$ states (the known upper bound is 2$^n$), with witness languages… Expand

Non-erasing Variants of the Chomsky-Schützenberger Theorem

- A. Okhotin
- Computer Science, Mathematics
- Developments in Language Theory
- 14 August 2012

The famous theorem by Chomsky and Schutzenberger ("The algebraic theory of context-free languages", 1963) states that every context-free language is representable as h(Dk∩R), where Dk is the Dyck… Expand

On the State Complexity of Star of Union and Star of Intersection

- Galina Jirásková, A. Okhotin
- Computer Science, Mathematics
- Fundam. Informaticae
- 1 April 2011

The state complexity of the star of union of an m-state DFA language and an n-state DFA language is proved to be 2 m+n−1−2 m−1−2 n−1+1 for every alphabet of at least two letters. The state complexity… Expand

Boolean grammars

- A. Okhotin
- Computer Science, Mathematics
- Inf. Comput.
- 1 October 2004

A new generalization of context-free grammars is introduced: Boolean grammars allow the use of all set-theoretic operations as an integral part of the formalism of rules. Rigorous semantics for these… Expand

On the equivalence of linear conjunctive grammars and trellis automata

- A. Okhotin
- Computer Science, Mathematics
- RAIRO Theor. Informatics Appl.
- 2004

This paper establishes computational equivalence of two seemingly unrelated concepts: linear conjunctive grammars and trellis automata. Trellis automata, also studied under the name of one-way… Expand

State complexity of power

- Michael Domaratzki, A. Okhotin
- Computer Science, Mathematics
- Theor. Comput. Sci.
- 1 May 2009

The number of states in a deterministic finite automaton (DFA) recognizing the language L^k, where L is regular language recognized by an n-state DFA, and k>=2 is a constant, is shown to be at most… Expand

On stateless multihead automata: Hierarchies and the emptiness problem

- O. Ibarra, J. Karhumäki, A. Okhotin
- Mathematics, Computer Science
- Theor. Comput. Sci.
- 2010

We look at stateless multihead finite automata in their two-way and one-way, deterministic and nondeterministic variations. The transition of a k-head automaton depends solely on the symbols… Expand

On the closure properties of linear conjunctive languages

- A. Okhotin
- Computer Science, Mathematics
- Theor. Comput. Sci.
- 18 April 2003

Linear conjunctive grammars are conjunctive grammars in which the body of each conjunct contains no more than a single nonterminal symbol. They can at the same time be thought of as a special case of… Expand

State complexity of cyclic shift

- Galina Jirásková, A. Okhotin
- Computer Science, Physics
- RAIRO Theor. Informatics Appl.
- 1 April 2008

The cyclic shift of a language L , defined as SHIFT( L ) = { vu | uv ∈ L }, is an operation known to preserve both regularity and context-freeness. Its descriptional complexity has been addressed in… Expand