Unlike some other reproductions of classic texts (1) We have not used OCR(Optical Character Recognition), as this leads to bad quality books with introduced typos. (2) In books where there are images such as portraits, maps, sketches etc We have endeavoured to keep the quality of these images, so they represent accurately the original artefact. Although occasionally there may be certain imperfections with these old texts, we feel they deserve to be made available for future generations to enjoy.

This book is the first English translation of the classic long paper Theorie der algebraischen Functionen einer Veranderlichen (Theory of algebraic functions of one variable), published by Dedekind and Weber in 1882. The translation has been enriched by a Translator's Introduction that provides historical background, and extensive commentary embedded in the translation itself. The translation, introduction, and commentary provide the first easy access to this important paper for a wide mathematical audience: students, historians of mathematics, and professional mathematicians. Why is the Dedekind-Weber paper important? In the 1850s, Riemann initiated a revolution in algebraic geometry by interpreting algebraic curves as surfaces covering the sphere. He obtained deep and striking results in pure algebra by intuitive arguments about surfaces and their topology. However, Riemann's arguments were not rigorous, and they remained in limbo until 1882, when Dedekind and Weber put them on a sound foundation. The key to this breakthrough was to develop the theory of algebraic functions in analogy with Dedekind's theory of algebraic numbers, where the concept of ideal plays a central role. By introducing such concepts into the theory of algebraic curves, Dedekind and Weber paved the way for modern algebraic geometry.

The nineteenth century saw the paradoxes and obscurities of eighteenth-century calculus gradually replaced by the exact theorems and statements of rigorous analysis. It became clear that all analysis could be deduced from the properties of the real numbers. But what are the real numbers and why do they have the properties we claim they do? In this charming and influential book, Richard Dedekind (1831-1916), Professor at the Technische Hochschule in Braunschweig, showed how to resolve this problem starting from elementary ideas. His method of constructing the reals from the rationals (the Dedekind cut) remains central to this day and was generalised by Conway in his construction of the 'surreal numbers'. This reissue of Dedekind's 1888 classic is of the 'second, unaltered' 1893 edition.

The invention of ideals by Dedekind in the 1870s was well ahead of its time, and proved to be the genesis of what today we would call algebraic number theory. His memoir 'Sur la Theorie des Nombres Entiers Algebriques' first appeared in instalments in the 'Bulletin des sciences mathematiques' in 1877. This is a translation of that work by John Stillwell, who also adds a detailed introduction that gives the historical background as well as outlining the mathematical obstructions that Dedekind was striving to overcome. Dedekind's memoir gives a candid account of his development of an elegant theory as well as providing blow-by-blow comments as he wrestled with the many difficulties encountered en route. A must for all number theorists.

Included in this volume are two essays on the theory of numbers: "Continuity and Irrational Numbers" and "The Nature and Meaning of Numbers." The text is an authorized translation by Wooster Woodruff Beman, Professor of Mathematics in the University of Michigan.

1. VORSTELLUNG DES ZAHLENGEBIETES Wir konnen jede ganze Zahl bildlich oder geometrisch darstellen. Nehmen wir zum Beispiel eine Linie von beliebiger Lange an, und auf derselben einen Punkt o. So konnen wir die Zahl eins so darstellen, indem wir eine beliebige konstante Lange auf dieser vom Nullpunkt aus nach rechts auftragen. Dieses Stuck reprasen- tirt uns also die Zahl eins. Wollen wir die Zahl 2 geometrisch darstellen, so wissen wir, dass 2 = 1 + 1 ist. Wir haben also nur die Einheit zweimal vom Nullpunkt aus aufzutragen, oder von 1 aus noch einmal und erhalten das geometrische Bild der Zahl 2 . Urn das Bild der Zahl 3 zu erhalten, konnen wir unsere Langeneinheit dreimal vom Nullpunkt aus auftragen. Ebenso k- nen wir 4,5,6,7,8 ... bis bildlich darstellen. Wollen wir hingegen eine gebrochene Zahl geometrisch darstellen, zum Beispiel t, so waren wir dies mit unsern Langeneinheiten 7 3 3 nicht imstande, denn 4 = 14 ' und 4 ist eine Grosse, die kleiner ist als 1. Wir mussen daher unsere Lange in noch klei- nere Theile eintheilen und zwar in Viertel. Dann sind wir erst 7 imstande, 4 geometrisch darzustellen.

Zur Rechtfertigung dieser Edition von Dedekinds beruhmtem elften Supplement zu Dirichlets "Vorlesungen uber Zahlentheorie" kann ich keine besseren Worte finden als die von Dedekind selbst am Schluss seines Vorworts zur zweiten Auflage dieser "V orlesungen" (1871): "Endlich habe ich mich bemuht, uberall, wo es mir moglich war, auf die Quellen zu verweisen, um den Leser zum Studium der Original werke zu veranlassen und in ihm ein Bild von den Fortschritten der Wissenschaft zu erwecken, deren ebenso tiefe wie erhabene Wahrheiten einen Schatz bilden, welcher die unvergangliche Frucht eines wahrhaft edelen Wett kampfes der europaischen Volker ist. " Das elfte Supplement, das zuerst in der dritten Auflage erschien, war eine Neufassung eines bedeutenden Abschnittes ( 159-170) des zehnten Supplementes der zweiten Auflage. Uber diesen Abschnitt schreibt Dedekind im Vorwort zur zweiten Auflage: "Endlich habe ich in dieses Supplement eine allgemeine Theorie der Ideale aufgenommen, um auf den Hauptgegenstand des ganzen Buches von einem hoheren Standpunkte aus ein neues Licht zu werfen; hierbei habe ich mich freilich auf die Darstellung der Grundlagen beschranken mussen, doch hoffe ich, dass das Streben nach charakteristischen Grund begriffen, welches in anderen Teilen der Mathematik mit so schonen Erfolgen gekront ist, mir nicht ganz missgluckt sein moge. " Schon vor Dedekind hatte Kronecker eine Idealtheorie der algebraischen Zahlkorper entwickelt, aber die Dedekindsche Theorie ist unabhangig von der Kroneckerschen entstanden."

The nineteenth century saw the paradoxes and obscurities of eighteenth-century calculus gradually replaced by the exact theorems and statements of rigorous analysis. It became clear that all analysis could be deduced from the properties of the real numbers. But what are the real numbers and why do they have the properties we claim they do? In this charming and influential book, Richard Dedekind (1831 1916), Professor at the Technische Hochschule in Braunschweig, showed how to resolve this problem starting from elementary ideas. His method of constructing the reals from the rationals (the Dedekind cut) remains central to this day and was generalised by Conway in his construction of the 'surreal numbers'. This reissue of Dedekind's 1888 classic is of the 'second, unaltered' 1893 edition.

This Is A New Release Of The Original 1901 Edition.

This Is A New Release Of The Original 1901 Edition.

I. Continuity and Irrational Numbers. II. The Nature and Meaning of Numbers.

I. Continuity and Irrational Numbers. II. The Nature and Meaning of Numbers.