Ian Chiswell acheived a Ph.D. at the University of Michigan in 1973 on the Bass-Serre theory of groups acting on trees. After three years as a temporary lecturer at the University of Birmingham he moved back to Queen Mary, University of London in 1976. His teaching experience dates back to 1968 when he was a teaching fellow at ... Read morethe University of Michigan. He spent the academic year 1972-73 in Germany at the Ruhr-Universitaet Bochum. He has published a monograph on lamda-trees, which are generalisations of ordinary trees. His work has connections with mathematical logic, mainly via non-standard free groups. Wilfrid Hodges achieved his DPhil at Oxford in 1970 for a thesis in model theory (mathematical logic). He has taught mathematics at London University for nearly forty years, first at Bedford College and then at Queen Mary, and also taught for visiting years in Los Angeles and Boulder (USA). Besides this book, he has four other textbooks of logic in print, at levels ranging from popular to research. He has served as president of the British Logic Colloquium and the European Association for Logic, Language and Information, and as vice-president of the London Mathematical Society. Show Less