This volume contains the revised versions of papers presented at the fourth international Workshop on Implementing Automata (WIA), held 17 19 July, 1999, at Potsdam University, Germany. As for its predecessors, the theme of WIA99 was the implementation of au- mata and grammars of all types and their application in other ?elds. The papers contributed to this volume address, among others, algorithmic issues regarding automata, image and dictionarystorage byautomata, and natural language p- cessing. In addition to the papers presented in these proceedings, the workshop - cluded a paper on quantum computing byC. Calude, E. Calude, and K. Svozil (published elsewhere), an invited lecture byW. Thomas on Algorithmic P- blems in the Theory of ?-Automata, a tutorial byM. Silberztein on the INTEX linguistic development environment, and several demonstrations of systems. The local arrangements for WIA99 were conducted byHelmut J urgensen, Suna Aydin, Oliver Boldt, Carsten Haustein, Beatrice Mix, and Lynda R- bins. The meeting was held in the Communs building, now the main university building, of the New Palace in the park of Sanssouci, Potsdam. The program committee for WIA99 was: A. Bruggemann-Klein Technische Universit at Munc hen J.-M. Champarnaud Universit e de Rouen F. Gun thner Universit at Munc hen H. Jurgensen Universit at Potsdam and Universityof Western Ontario D. Maurel Universit e de Tours D. Raymond Gateway Group Inc. K. Salomaa Universityof Western Ontario W. Thomas Rheinisch-Westf alische Technische Hochschule Aachen B. Watson Ribbit Software Systems Inc. FA Minimisation Heuristics for a Class of Finite Languages.- SEA: A Symbolic Environment for Automata Theory.- Analysis of Reactive Systems with n Timers.- Animation of the Generation and Computation of Finite Automata for Learning Software.- Metric Lexical Analysis.- State Complexity of Basic Operations on Finite Languages.- Treatment of Unknown Words.- Computing Entropy Maps of Finite-Automaton-Encoded Binary Images.- Thompson Digraphs: A Characterization.- Finite Automata Encoding Geometric Figures.- Compressed Storage of Sparse Finite-State Transducers.- An Extendible Regular Expression Compiler for Finite-State Approaches in Natural Language Processing.- Multiset Processing by Means of Systems of Finite State Transducers.- A Structural Method for Output Compaction of Sequential Automata Implemented as Circuits.- An Algorithm to Verify Local Threshold Testability of Deterministic Finite Automata.- A Taxonomy of Algorithms for Constructing Minimal Acyclic Deterministic Finite Automata.
