Grammars of natural languages can be expressed as mathematical objects, similar to computer programs. Such a formal presentation of grammars facilitates mathematical reasoning with grammars (and the languages they denote), as well as computational implementation of grammar processors. This book presents one of the most commonly used grammatical formalisms, Unification Grammars, which underlies contemporary linguistic theories such as Lexical-Functional Grammar (LFG) and Head-driven Phrase Structure Grammar (HPSG). The book provides a robust and rigorous exposition of the formalism that is both mathematically well-founded and linguistically motivated. While the material is presented formally, and much of the text is mathematically oriented, a core chapter of the book addresses linguistic applications and the implementation of several linguistic insights in unification grammars. Dozens of examples and numerous exercises (many with solutions) illustrate key points. Graduate students and researchers in both computer science and linguistics will find this book a valuable resource.

The symposium "Languages: From Formal to Natural," celebrating the 65th birthday of Nissim Francez, was held on May 24-25, 2009 at the Technion, Haifa. The symposium consisted of two parts, a veri?cation day and a language day, and covered all areas of Nissim's past and present research interests, areas which he has inspiringly in?uenced and to which he has contributed so much. This volume comprises severalpapers presentedat the symposium, as wellas additional articles that were contributed by Nissim's friends and colleagues who were unable to attend the event. We thank the authors for their contributions. Wearealsogratefultothereviewersfor their dedicated and timely work. Nissim Francez was born on January 19, 1944. In 1962 he started his mat- matical education at the Hebrew University. He received a BSc in Mathematics in 1965, and, after four years of military service, started his MSc studies in Computer Science at the Weizmann Institute of Science under the supervision of Amir Pnueli. After completing the MSc program in 1971, Nissim continued his studies toward a PhD, again, at the Weizmann Institute of Science and, again, under the supervisionof Amir Pnueli. Nissim wasawardeda PhDin Computer Science in 1976.