The description for this book, Knot Groups. Annals of Mathematics Studies. (AM-56), Volume 56, will be forthcoming.

These lectures, delivered by Professor Mumford at Harvard in 1963-1964, are devoted to a study of properties of families of algebraic curves, on a non-singular projective algebraic curve defined over an algebraically closed field of arbitrary characteristic. The methods and techniques of Grothendieck, which have so changed the character of algebraic geometry in recent years, are used systematically throughout. Thus the classical material is presented from a new viewpoint.

The description for this book, Compositional Methods in Homotopy Groups of Spheres. (AM-49), will be forthcoming.

During the summer of 1965, an informal seminar in geometric topology was held at the University of Wisconsin under the direction of Professor Bing. Twenty-five of these lectures are included in this study, among them Professor Bing's lecture describing the recent attacks of Haken and Poincaré on the Poincaré conjectures, and sketching a proof of Haken's main result.

Das Buch beginnt mit einem alten Zaubertrick - Man nehme eine 3-stellige Zahl, etwa 782, kehre sie um, ziehe die kleinere von der größeren ab und addiere dazu die Umkehrung. Also - 782 - 287 = 495, dann 495 + 594. Und schon ist man mitten in der Wunderwelt der Mathematik, denn das Ergebnis ist immer - 1089. Mit solchen und vielen weiteren Beispielen aus Alltag, Geschichte und Wissenschaft gelingt es David Acheson, die faszinierende Welt der Mathematik zu erschließen - ein geistreicher Überblick, eine für jeden verständliche Einführung.

The last book XIII of Euclid's Elements deals with the regular solids which therefore are sometimes considered as crown of classical geometry. More than two thousand years later around 1850 Schl~fli extended the classification of regular solids to four and more dimensions. A few decades later, thanks to the invention of group and invariant theory the old three dimensional regular solid were involved in the development of new mathematical ideas: F. Klein (Lectures on the Icosa hedron and the Resolution of Equations of Degree Five, 1884) emphasized the relation of the regular solids to the finite rotation groups. He introduced complex coordinates and by means of invariant theory associated polynomial equations with these groups. These equations in turn describe isolated singularities of complex surfaces. The structure of the singularities is investigated by methods of commutative algebra, algebraic and complex analytic geometry, differential and algebraic topology. A paper by DuVal from 1934 (see the References), in which resolutions play an important rele, marked an early stage of these investigations. Around 1970 Klein's polynomials were again related to new mathematical ideas: V. I. Arnold established a hierarchy of critical points of functions in several variables according to growing com plexity. In this hierarchy Kleinls polynomials describe the "simple" critical points.