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An extension of data automata that captures XPath

Mikołaj Bojańczyk ; Sławomir Lasota.

We define a new kind of automata recognizing properties of data words or data trees and prove that the automata capture all queries definable in Regular XPath. We show that the automata-theoretic approach may be applied to answer decidability and expressibility questions for XPath.

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Reachability Problem for Weak Multi-Pushdown Automata

Wojciech Czerwiński ; Piotr Hofman ; SŁawomir Lasota.

This paper is about reachability analysis in a restricted subclass of multi-pushdown automata. We assume that the control states of an automaton are partially ordered, and all transitions of an automaton go downwards with respect to the order. We prove decidability of the reachability problem, and&nbsp;[&hellip;]

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Automata theory in nominal sets

Mikołaj Bojańczyk ; Bartek Klin ; Sławomir Lasota.

We study languages over infinite alphabets equipped with some structure that can be tested by recognizing automata. We develop a framework for studying such alphabets and the ensuing automata theory, where the key role is played by an automorphism group of the alphabet. In the process, we generalize&nbsp;[&hellip;]

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Simulation Problems Over One-Counter Nets

Piotr Hofman ; Slawomir Lasota ; Richard Mayr ; Patrick Totzke.

One-counter nets (OCN) are finite automata equipped with a counter that can store non-negative integer values, and that cannot be tested for zero. Equivalently, these are exactly 1-dimensional vector addition systems with states. We show that both strong and weak simulation preorder on OCN are&nbsp;[&hellip;]

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Regular Separability of One Counter Automata

Wojciech Czerwiński ; Sławomir Lasota.

The regular separability problem asks, for two given languages, if there exists a regular language including one of them but disjoint from the other. Our main result is decidability, and PSpace-completeness, of the regular separability problem for languages of one counter automata without zero tests&nbsp;[&hellip;]

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Definable isomorphism problem

Khadijeh Keshvardoost ; Bartek Klin ; Sławomir Lasota ; Joanna Ochremiak ; Szymon Toruńczyk.

We investigate the isomorphism problem in the setting of definable sets (equivalent to sets with atoms): given two definable relational structures, are they related by a definable isomorphism? Under mild assumptions on the underlying structure of atoms, we prove decidability of the problem. The core&nbsp;[&hellip;]

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Determinisability of register and timed automata

Lorenzo Clemente ; Sławomir Lasota ; Radosław Piórkowski.

The deterministic membership problem for timed automata asks whether the timed language given by a nondeterministic timed automaton can be recognised by a deterministic timed automaton. An analogous problem can be stated in the setting of register automata. We draw the complete&nbsp;[&hellip;]

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