Trees are among the most fundamental and ubiquitous structures in mathematics and computer science. The notion of "tree" appears in many seemingly different areas from graph theory to universal algebra to logic. Tree languages and automata on trees have been studied extensively since the 1960s from both a purely mathematical and application point of view. Though the theory of tree automata and tree languages may have come into existence by generalizing string automata and languages, but it could not have stayed alive for long as a mere generalization. Apart from its intrinsic interest, this theory has found several applications and offers new perspectives to various parts of mathematical linguistics. It has been applied to the study of databases and XML schema languages, and provides tools for syntactic pattern recognition. When trees are defined as terms, universal algebra becomes directly applicable to tree automata and tree languages and, on the other hand, the theory of tree automata and tree languages suggests new notions and problems to universal algebra. In this book, the theory has been studied from the algebraic viewpoint.

Semigroups, Automata, Universal Algebra, Varieties

Further Developments in the Theory and Practice of Cybercartography, Third Edition, Volume Nine, presents a substantively updated edition of a classic text on cybercartography, presenting new and returning readers alike with the latest advances in the field. The book examines the major elements of cybercartography and embraces an interactive, dynamic, multisensory format with the use of multimedia and multimodal interfaces. Material covering the major elements, key ideas and definitions of cybercartography is newly supplemented by several chapters on two emerging areas of study, including international dimensions and language mapping. This new edition delves deep into Mexico, Brazil, Denmark, Iran and Kyrgyzstan, demonstrating how insights emerge when cybercartography is applied in different cultural contexts. Meanwhile, other chapters contain case studies by a talented group of linguists who are breaking new ground by applying cybercartography to language mapping, a breakthrough that will provide new ways of understanding the distribution and movement of language and culture. Highlights the relationship between cybercartography and critical geography Incorporates the latest developments in the field of cybercartography, including International Dimensions and Language Mapping Showcases the legal, ethical and policy implications of mapping local and traditional knowledge

Formal Language Theory: Perspectives and Open Problems focuses on the trends and major open problems on the formal language theory. The selection first ponders on the methods for specifying families of formal languages, open problems about regular languages, and generators of cones and cylinders. Discussions focus on cylinders of algebraic languages, cone of algebraic languages, regularity of noncounting classes, group complexity, specification formalism, and grammars. The publication then elaborates on very small families of algebraic nonrational languages and formal languages and their relation to automata. The book tackles morphisms on free monoids and language theory, homomorphisms, and survey of results and open problems in the mathematical theory of L systems. Topics include single finite substitutions iterated, single homomorphisms iterated, representation of language families, homomorphism equivalence on a language, and problems about infinite words. The selection is a valuable source of data for researchers interested in the formal language theory.

The theory of tree languages, founded in the late Sixties and still active in the Seventies, was much less active during the Eighties. Now there is a simultaneous revival in several countries, with a number of significant results proved in the past five years. A large proportion of them appear in the present volume. The editors of this volume suggested that the authors should write comprehensive half-survey papers. This collection is therefore useful for everyone interested in the theory of tree languages as it covers most of the recent questions which are not treated in the very few rather old standard books on the subject. Trees appear naturally in many chapters of computer science and each new property is likely to result in improvement of some computational solution of a real problem in handling logical formulae, data structures, programming languages on systems, algorithms etc. The point of view adopted here is to put emphasis on the properties themselves and their rigorous mathematical exposition rather than on the many possible applications. This volume is a useful source of concepts and methods which may be applied successfully in many situations: its philosophy is very close to the whole philosophy of the ESPRIT Basic Research Actions and to that of the European Association for Theoretical Computer Science.

The refereed proceedings of the 7th International Conference on Developments in Language Theory, DLT 2003, held in Szeged, Hungary, in July 2003. The 27 revised full papers presented together with 7 invited papers were carefully reviewed and selected from 57 submissions. All current aspects in language theory are addressed, in particular grammars, acceptors, and transducers for strings, trees, graphs, arrays, etc; algebraic theories for automata and languages; combinatorial properties of words and languages; formal power series; decision problems; efficient algorithms for automata and languages; and relations to complexity theory and logic, picture description and analysis, DNA computing, quantum computing, cryptography, and concurrency.