Displaying similar documents to “String distances and intrusion detection: Bridging the gap between formal languages and computer security”

Translation from classical two-way automata to pebble two-way automata

Viliam Geffert, L'ubomíra Ištoňová (2010)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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We study the relation between the standard two-way automata and more powerful devices, namely, two-way finite automata equipped with some ℓ additional “pebbles” that are movable along the input tape, but their use is restricted (nested) in a stack-like fashion. Similarly as in the case of the classical two-way machines, it is not known whether there exists a polynomial trade-off, in the number of states, between the nondeterministic and deterministic two-way automata with ℓ nested pebbles....

Bidirectional string assembling systems

Martin Kutrib, Matthias Wendlandt (2014)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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We introduce and investigate several variants of a bidirectional string assembling system, which is a computational model that generates strings from copies of assembly units. The underlying mechanism is based on two-sided piecewise assembly of a double-stranded sequence of symbols, where the upper and lower strand have to match. The generative capacities and the relative power of the variants are our main interest. In particular, we prove that bidirectional string assembling system...

Complexity results for prefix grammars

Markus Lohrey, Holger Petersen (2005)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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Resolving an open problem of Ravikumar and Quan, we show that equivalence of prefix grammars is complete in PSPACE. We also show that membership for these grammars is complete in P (it was known that this problem is in P) and characterize the complexity of equivalence and inclusion for monotonic grammars. For grammars with several premises we show that membership is complete in EXPTIME and hard for PSPACE for monotonic grammars.

On the equivalence of linear conjunctive grammars and trellis automata

Alexander Okhotin (2004)

RAIRO - Theoretical Informatics and Applications - Informatique Théorique et Applications

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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 real-time cellular automata, have been known since early 1980s as a purely abstract model of parallel computers, while linear conjunctive grammars, introduced a few years ago, are linear context-free grammars extended with an explicit intersection operation. Their equivalence implies the equivalence...