CONTENTS 7 Acknowledgments Many people gave substantial suggestions to improve the contents of this book. These are, in alphabetic order, Introduction During the past few years, several of us have been asked many times about references on finite tree automata. On one hand, this is the witness of the liveness of this field. On the other hand, it was difficult to answer. Besides several excellent survey chapters on more specific topics, there is only one monograph devoted to tree automata by Gécseg and Steinby. Unfortunately, it is now impossible to find a copy of it and a lot of work has been done on tree automata since the publication of this book. Actually using tree automata has proved to be a powerful approach to simplify and extend previously known results, and also to find new results. For instance recent works use tree automata for application in abstract interpretation using set constraints, rewriting, automated theorem proving and program verification, databases and XML schema languages. Tree automata have been designed a long time ago in the context of circuit verification. Many famous researchers contributed to this school which was headed by A. Church in the late 50's and the early 60's: B. Trakhtenbrot, Many new ideas came out of this program. For instance the connections between automata and logic. Tree automata also appeared first in this framework, following the work of Doner, Thatcher and Wright. In the 70's many new results were established concerning tree automata, which lose a bit their connections with the applications and were studied for their own. In particular, a problem was the very high complexity of decision procedures for the monadic second order logic. Applications of tree automata to program verification revived in the 80's, after the relative failure of automated deduction in this field. It is possible to verify temporal logic formulas (which are particular Monadic Second Order Formulas) on simpler (small) programs. Automata, and in particular tree automata, also appeared as an approximation of programs on which fully automated tools can be used. New results were obtained connecting properties of programs or type systems or rewrite systems with automata. Our goal is to fill in the existing gap and to provide a textbook which presents the basics of tree automata and several variants of tree automata which have been devised for applications in the aforementioned domains. We shall discuss only finite tree automata, and the …

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Tree Automata Techniques and Applications

The study of graph structure has advanced in recent years with great strides: finite graphs can be described algebraically, enabling them to be constructed out of more basic elements. Separately the properties of graphs can be studied in a logical language called monadic second-order logic. In this book, these two features of graph structure are brought together for the first time in a presentation that unifies and synthesizes research over the last 25 years. The author not only provides a thorough description of the theory, but also details its applications, on the one hand to the construction of graph algorithms, and, on the other to the extension of formal language theory to finite graphs. Consequently the book will be of interest to graduate students and researchers in graph theory, finite model theory, formal language theory, and complexity theory.

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Graph Structure and Monadic Second-Order Logic: A Language-Theoretic Approach

We present a logic that can express properties of freshness, secrecy, structure, and behavior of concurrent systems. In addition to standard logical and temporal operators, our logic includes spatial operations corresponding to composition, local name restriction, and a primitive fresh name quantifier. Properties can also be defined by recursion; a central aim of this paper is then the combination of a logical notion of freshness with inductive and coinductive definitions of properties.

A spatial logic for concurrency (part I)

We present a modal logic for describing the spatial organization and the behavior of distributed systems. In addition to standard logical and temporal operators, our logic includes spatial operations corresponding to process composition and name hiding, and a fresh quantifier.

A Spatial Logic for Concurrency (Part II)

http://liacs.leidenuniv.nl/~stefanovtp/courses/StudentenSeminarium/Papers/FI2/AXML.pdf

Automata for XML---A survey

The ambient calculus is a formalism for describing the mobility of both software and hardware. The ambient logic is a modal logic designed to specify properties of distributed and mobile computations programmed in the ambient calculus. In this paper we investigate the border between decidable and undecidable cases of model checking mobile ambients for some fragments of the ambient calculus and the ambient logic.

Recently, Cardelli and Gordon presented a model-checking algorithm for a fragment of the calculus (without name restriction and without replication) against a fragment of the logic (without composition adjunct) and asked the question, whether this algorithm could be extended to include either replication in the calculus or composition adjunct in the logic. Here we answer this question negatively: it is not possible to extend the algorithm, because each of these extensions leads to undecidability of the problem. On the other hand, we extend the algorithm to the calculus with name restriction and logic with new constructs for reasoning about restricted names.

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The Decidability of Model Checking Mobile Ambients

The ambient calculus is a formalism for describing the mobility of both software and hardware The ambient logic is a modal logic designed to specify properties of distributed and mobile computations programmed in the ambient calculus In this paper we investigate the border between decidable and undecidable cases of model checking mobile ambients for some fragments of the ambient calculus and the ambient logic

Recently, Cardelli and Gordon presented a model-checking algorithm for a fragment of the calculus (without name restriction and without replication) against a fragment of the logic (without composition adjunct) and asked the question, whether this algorithm could be extended to include either replication in the calculus or composition adjunct in the logic Here we answer this question negatively: it is not possible to extend the algorithm, because each of these extensions leads to undecidability of the problem On the other hand, we extend the algorithm to the calculus with name restriction and logic with new constructs for reasoning about restricted names

Information extraction from semi-structured documents requires to find
n-ary queries in trees that define appropriate sets of n-tuples of
nodes. We propose new representation formalisms for 
n-ary queries by tree automata that we prove to capture MSO. We then 
investigate n-ary queries by unambiguous tree automata which are
relevant for query induction in multi-slot information extraction.
We show that this representation formalism captures the 
class of n-ary queries that are finite unions of Cartesian closed 
queries, a property we prove decidable.

N-ary Queries by Tree Automata.

We define a finite-control fragment of the ambient calculus, a formalism for describing distributed and mobile computations. A series of examples demonstrates the expressiveness of our fragment. In particular, we encode the choice-free, finite-control, synchronous ?-calculus. We present an algorithm for model checking this fragment against the ambient logic (without composition adjunct). This is the first proposal of a model checking algorithm for ambients to deal with recursively-defined, possibly nonterminating, processes. Moreover, we show that the problem is PSPACE-complete, like other fragments considered in the literature. Finite-control versions of other process calculi are obtained via various syntactic restrictions. Instead, we rely on a novel type system that bounds the number of active ambients and outputs in a process; any typable process has only a finite number of derivatives.

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Finite-Control Mobile Ambients

We investigate n-ary node selection queries in trees by successful runs of tree automata. We show that run-based n-ary queries capture MSO, contribute algorithms for enumerating answers of n-ary queries, and study the complexity of the problem. We investigate the subclass of run-based n-ary queries by unambiguous tree automata.

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Jean-Marc Talbot

Papers

The Decidability of Model Checking Mobile Ambients

The Decidability of Model Checking Mobile Ambients

N-ary Queries by Tree Automata.

Finite-Control Mobile Ambients

N-ary queries by tree automata