Vorlesungen über Zahlentheorie
for Lectures on Number Theory
) is a textbook of number theory
written by German
mathematicians P.G.L. Dirichlet
and Richard Dedekind
, and published in 1863
Based on Dirichlet's number theory course at the University of Göttingen, the Vorlesungen were edited by Dedekind and published after Dirichlet's death. Dedekind added several appendices to the Vorlesungen, in which he collected further results of Dirichlet's and also developed his own original mathematical ideas.
cover topics in elementary number theory, algebraic number theory
and analytic number theory
, including modular arithmetic
, quadratic congruences, quadratic reciprocity
and binary quadratic forms
The contents of Professor John Stillwell's 1999 translation of the Vorlesungen
are as follows
- Chapter 1. On the divisibility of numbers
- Chapter 2. On the congruence of numbers
- Chapter 3. On quadratic residues
- Chapter 4. On quadratic forms
- Chapter 5. Determination of the class number of binary quadratic forms
- Supplement I. Some theorems from Gauss's theory of circle division
- Supplement II. On the limiting value of an infinite series
- Supplement III. A geometric theorem
- Supplement IV. Genera of quadratic forms
- Supplement V. Power residues for composite moduli
- Supplement VI. Primes in arithmetic progressions
- Supplement VII. Some theorems from the theory of circle division
- Supplement VIII. On the Pell equation
- Supplement IX. Convergence and continuity of some infinite series
This translation does not include Dedekind's Supplements X and XI in which he begins to develop the theory of ideals.
Chapters 1 to 4 cover similar ground to Gauss' Disquisitiones Arithmeticae, and Dedekind added footnotes which specifically cross-reference the relevant sections of the Disquisitiones. These chapters can be thought of as a summary of existing knowledge, although Dirichlet simplifies Gauss' presentation, and introduces his own proofs in some places.
Chapter 5 contains Dirichlet's derivation of the class number formula for real and imaginary quadratic fields. Although other mathematicians had conjectured similar formulae, Dirichlet gave the first rigorous proof.
Supplement VI contains Dirichlet's proof that an arithmetic progression of the form a+nd where a and d are coprime contains an infinite number of primes.
can be seen as a watershed between the classical number theory of Fermat
, and the modern number theory of Dedekind, Riemann
. Dirichlet does not explicitly recognise the concept of the group
that is central to modern algebra
, but many of his proofs show an implicit understanding of group theory
The Vorlesungen contains two key results in number theory which were first proved by Dirichlet. The first of these is the class number formulae for binary quadratic forms. The second is a proof that arithmetic progressions contains an infinite number of primes (known as Dirichlet's theorem); this proof introduces Dirichlet L-series. These results are important milestones in the development of analytic number theory.
- P.G.L. Dirichlet, R. Dedekind tr. John Stillwell: Lectures on Number Theory, American Mathematical Society, 1999 ISBN 0821820176
Note that the Göttinger Digitalisierungszentrum has a scanned copy of the original, 2nd edition text (in German).