Class Number One Problems
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An Introduction to Iwasawa Theory
An Introduction to Iwasawa Theory Notes by Jim L. Brown 2 Contents 1 Introduction 5 2 Background Material 9 2.1 AlgebraicNumberTheory . 9 2.2 CyclotomicFields........................... 11 2.3 InfiniteGaloisTheory . 16 2.4 ClassFieldTheory .......................... 18 2.4.1 GlobalClassFieldTheory(ideals) . 18 2.4.2 LocalClassFieldTheory . 21 2.4.3 GlobalClassFieldTheory(ideles) . 22 3 SomeResultsontheSizesofClassGroups 25 3.1 Characters............................... 25 3.2 L-functionsandClassNumbers . 29 3.3 p-adicL-functions .......................... 31 3.4 p-adic L-functionsandClassNumbers . 34 3.5 Herbrand’sTheorem . .. .. .. .. .. .. .. .. .. .. 36 4 Zp-extensions 41 4.1 Introduction.............................. 41 4.2 PowerSeriesRings .......................... 42 4.3 A Structure Theorem on ΛO-modules ............... 45 4.4 ProofofIwasawa’stheorem . 48 5 The Iwasawa Main Conjecture 61 5.1 Introduction.............................. 61 5.2 TheMainConjectureandClassGroups . 65 5.3 ClassicalModularForms. 68 5.4 ConversetoHerbrand’sTheorem . 76 5.5 Λ-adicModularForms . 81 5.6 ProofoftheMainConjecture(outline) . 85 3 4 CONTENTS Chapter 1 Introduction These notes are the course notes from a topics course in Iwasawa theory taught at the Ohio State University autumn term of 2006. They are an amalgamation of results found elsewhere with the main two sources being [Wash] and [Skinner]. The early chapters are taken virtually directly from [Wash] with my contribution being the choice of ordering as well as adding details to some arguments. Any mistakes in the notes are mine. There are undoubtably type-o’s (and possibly mathematical errors), please send any corrections to [email protected]. As these are course notes, several proofs are omitted and left for the reader to read on his/her own time. -
Automorphic Functions and Fermat's Last Theorem(3)
Jiang and Wiles Proofs on Fermat Last Theorem (3) Abstract D.Zagier(1984) and K.Inkeri(1990) said[7]:Jiang mathematics is true,but Jiang determinates the irrational numbers to be very difficult for prime exponent p.In 1991 Jiang studies the composite exponents n=15,21,33,…,3p and proves Fermat last theorem for prime exponenet p>3[1].In 1986 Gerhard Frey places Fermat last theorem at the elliptic curve that is Frey curve.Andrew Wiles studies Frey curve. In 1994 Wiles proves Fermat last theorem[9,10]. Conclusion:Jiang proof(1991) is direct and simple,but Wiles proof(1994) is indirect and complex.If China mathematicians had supported and recognized Jiang proof on Fermat last theorem,Wiles would not have proved Fermat last theorem,because in 1991 Jiang had proved Fermat last theorem.Wiles has received many prizes and awards,he should thank China mathematicians. - Automorphic Functions And Fermat’s Last Theorem(3) (Fermat’s Proof of FLT) 1 Chun-Xuan Jiang P. O. Box 3924, Beijing 100854, P. R. China [email protected] Abstract In 1637 Fermat wrote: “It is impossible to separate a cube into two cubes, or a biquadrate into two biquadrates, or in general any power higher than the second into powers of like degree: I have discovered a truly marvelous proof, which this margin is too small to contain.” This means: xyznnnn+ =>(2) has no integer solutions, all different from 0(i.e., it has only the trivial solution, where one of the integers is equal to 0). It has been called Fermat’s last theorem (FLT). -
Introduction to L-Functions: Dedekind Zeta Functions
Introduction to L-functions: Dedekind zeta functions Paul Voutier CIMPA-ICTP Research School, Nesin Mathematics Village June 2017 Dedekind zeta function Definition Let K be a number field. We define for Re(s) > 1 the Dedekind zeta function ζK (s) of K by the formula X −s ζK (s) = NK=Q(a) ; a where the sum is over all non-zero integral ideals, a, of OK . Euler product exists: Y −s −1 ζK (s) = 1 − NK=Q(p) ; p where the product extends over all prime ideals, p, of OK . Re(s) > 1 Proposition For any s = σ + it 2 C with σ > 1, ζK (s) converges absolutely. Proof: −n Y −s −1 Y 1 jζ (s)j = 1 − N (p) ≤ 1 − = ζ(σ)n; K K=Q pσ p p since there are at most n = [K : Q] many primes p lying above each rational prime p and NK=Q(p) ≥ p. A reminder of some algebraic number theory If [K : Q] = n, we have n embeddings of K into C. r1 embeddings into R and 2r2 embeddings into C, where n = r1 + 2r2. We will label these σ1; : : : ; σr1 ; σr1+1; σr1+1; : : : ; σr1+r2 ; σr1+r2 . If α1; : : : ; αn is a basis of OK , then 2 dK = (det (σi (αj ))) : Units in OK form a finitely-generated group of rank r = r1 + r2 − 1. Let u1;:::; ur be a set of generators. For any embedding σi , set Ni = 1 if it is real, and Ni = 2 if it is complex. Then RK = det (Ni log jσi (uj )j)1≤i;j≤r : wK is the number of roots of unity contained in K. -
Notes on the Riemann Hypothesis Ricardo Pérez-Marco
Notes on the Riemann Hypothesis Ricardo Pérez-Marco To cite this version: Ricardo Pérez-Marco. Notes on the Riemann Hypothesis. 2018. hal-01713875 HAL Id: hal-01713875 https://hal.archives-ouvertes.fr/hal-01713875 Preprint submitted on 21 Feb 2018 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. NOTES ON THE RIEMANN HYPOTHESIS RICARDO PEREZ-MARCO´ Abstract. Our aim is to give an introduction to the Riemann Hypothesis and a panoramic view of the world of zeta and L-functions. We first review Riemann's foundational article and discuss the mathematical background of the time and his possible motivations for making his famous conjecture. We discuss some of the most relevant developments after Riemann that have contributed to a better understanding of the conjecture. Contents 1. Euler transalgebraic world. 2 2. Riemann's article. 8 2.1. Meromorphic extension. 8 2.2. Value at negative integers. 10 2.3. First proof of the functional equation. 11 2.4. Second proof of the functional equation. 12 2.5. The Riemann Hypothesis. 13 2.6. The Law of Prime Numbers. 17 3. On Riemann zeta-function after Riemann. -
And Siegel's Theorem We Used Positivi
Math 259: Introduction to Analytic Number Theory A nearly zero-free region for L(s; χ), and Siegel's theorem We used positivity of the logarithmic derivative of ζq to get a crude zero-free region for L(s; χ). Better zero-free regions can be obtained with some more effort by working with the L(s; χ) individually. The situation is most satisfactory for 2 complex χ, that is, for characters with χ = χ0. (Recall that real χ were also the characters that gave us the most difficulty6 in the proof of L(1; χ) = 0; it is again in the neighborhood of s = 1 that it is hard to find a good zero-free6 region for the L-function of a real character.) To obtain the zero-free region for ζ(s), we started with the expansion of the logarithmic derivative ζ 1 0 (s) = Λ(n)n s (σ > 1) ζ X − − n=1 and applied the inequality 1 0 (z + 2 +z ¯)2 = Re(z2 + 4z + 3) = 3 + 4 cos θ + cos 2θ (z = eiθ) ≤ 2 it iθ s to the phases z = n− = e of the terms n− . To apply the same inequality to L 1 0 (s; χ) = χ(n)Λ(n)n s; L X − − n=1 it it we must use z = χ(n)n− instead of n− , obtaining it 2 2it 0 Re 3 + 4χ(n)n− + χ (n)n− : ≤ σ Multiplying by Λ(n)n− and summing over n yields L0 L0 L0 0 3 (σ; χ ) + 4 Re (σ + it; χ) + Re (σ + 2it; χ2) : (1) ≤ − L 0 − L − L 2 Now we see why the case χ = χ0 will give us trouble near s = 1: for such χ the last term in (1) is within O(1) of Re( (ζ0/ζ)(σ + 2it)), so the pole of (ζ0/ζ)(s) at s = 1 will undo us for small t . -
Fundamental Theorems in Mathematics
SOME FUNDAMENTAL THEOREMS IN MATHEMATICS OLIVER KNILL Abstract. An expository hitchhikers guide to some theorems in mathematics. Criteria for the current list of 243 theorems are whether the result can be formulated elegantly, whether it is beautiful or useful and whether it could serve as a guide [6] without leading to panic. The order is not a ranking but ordered along a time-line when things were writ- ten down. Since [556] stated “a mathematical theorem only becomes beautiful if presented as a crown jewel within a context" we try sometimes to give some context. Of course, any such list of theorems is a matter of personal preferences, taste and limitations. The num- ber of theorems is arbitrary, the initial obvious goal was 42 but that number got eventually surpassed as it is hard to stop, once started. As a compensation, there are 42 “tweetable" theorems with included proofs. More comments on the choice of the theorems is included in an epilogue. For literature on general mathematics, see [193, 189, 29, 235, 254, 619, 412, 138], for history [217, 625, 376, 73, 46, 208, 379, 365, 690, 113, 618, 79, 259, 341], for popular, beautiful or elegant things [12, 529, 201, 182, 17, 672, 673, 44, 204, 190, 245, 446, 616, 303, 201, 2, 127, 146, 128, 502, 261, 172]. For comprehensive overviews in large parts of math- ematics, [74, 165, 166, 51, 593] or predictions on developments [47]. For reflections about mathematics in general [145, 455, 45, 306, 439, 99, 561]. Encyclopedic source examples are [188, 705, 670, 102, 192, 152, 221, 191, 111, 635]. -
Arxiv:1802.06193V3 [Math.NT] 2 May 2018 Etr ...I Hsppr Efi H Udmna Discrimi Fundamental the fix Fr We Quadratic Paper, Binary I This a Inverse by in the Squares 1.4.]
THE LEAST PRIME IDEAL IN A GIVEN IDEAL CLASS NASER T. SARDARI Abstract. Let K be a number field with the discriminant DK and the class number hK , which has bounded degree over Q. By assuming GRH, we prove that every ideal class of K contains a prime ideal with norm less 2 2 than hK log(DK ) and also all but o(hK ) of them have a prime ideal with 2+ǫ norm less than hK log(DK ) . For imaginary quadratic fields K = Q(√D), by assuming Conjecture 1.2 (a weak version of the pair correlation conjecure), we improve our bounds by removing a factor of log(D) from our bounds and show that these bounds are optimal. Contents 1. Introduction 1 1.1. Motivation 1 1.2. Repulsion of the prime ideals near the cusp 5 1.3. Method and Statement of results 6 Acknowledgements 7 2. Hecke L-functions 7 2.1. Functional equation 7 2.2. Weil’s explicit formula 8 3. Proof of Theorem 1.8 8 4. Proof of Theorem 1.1 11 References 12 1. Introduction 1.1. Motivation. One application of our main result addresses the optimal upper arXiv:1802.06193v3 [math.NT] 2 May 2018 bound on the least prime number represented by a binary quadratic form up to a power of the logarithm of its discriminant. Giving sharp upper bound of this form on the least prime or the least integer representable by a sum of two squares is crucial in the analysis of the complexity of some algorithms in quantum compiling. -
Class Number Formula for Dihedral Extensions 2
CLASS NUMBER FORMULA FOR DIHEDRAL EXTENSIONS LUCA CAPUTO AND FILIPPO A. E. NUCCIO MORTARINO MAJNO DI CAPRIGLIO Abstract. We give an algebraic proof of a class number formula for dihedral extensions of number fields of degree 2q, where q is any odd integer. Our formula expresses the ratio of class numbers as a ratio of orders of cohomology groups of units and allows one to recover similar formulas which have appeared in the literature. As a corollary of our main result we obtain explicit bounds on the (finitely many) possible values which can occur as ratio of class numbers in dihedral extensions. Such bounds are obtained by arithmetic means, without resorting to deep integral representation theory. 1. Introduction Let k be a number field and let M/k be a finite Galois extension. For a subgroup H Gal(M/k), let χH denote the rational character of the permutation representation defined by the Gal(M/k)-set⊆ Gal(M/k)/H. If M/k is non-cyclic, then there exists a relation n χ =0 H · H XH where nH Z are not all 0 and H runs through the subgroups of Gal(M/k). Using the formalism of Artin L-functions∈ and the formula for the residue at 1 of the Dedekind zeta-function, Brauer showed in [Bra51] that the above relation translates into the following formula nH H nH wM (1.1) (hM H ) = RM H YH YH where, for a number field E, hE, RE, wE denote the class number, the regulator and the order of the group of roots of unity of E, respectively. -
The Legacy of Leonhard Euler: a Tricentennial Tribute (419 Pages)
P698.TP.indd 1 9/8/09 5:23:37 PM This page intentionally left blank Lokenath Debnath The University of Texas-Pan American, USA Imperial College Press ICP P698.TP.indd 2 9/8/09 5:23:39 PM Published by Imperial College Press 57 Shelton Street Covent Garden London WC2H 9HE Distributed by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. THE LEGACY OF LEONHARD EULER A Tricentennial Tribute Copyright © 2010 by Imperial College Press All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the Publisher. For photocopying of material in this volume, please pay a copying fee through the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, USA. In this case permission to photocopy is not required from the publisher. ISBN-13 978-1-84816-525-0 ISBN-10 1-84816-525-0 Printed in Singapore. LaiFun - The Legacy of Leonhard.pmd 1 9/4/2009, 3:04 PM September 4, 2009 14:33 World Scientific Book - 9in x 6in LegacyLeonhard Leonhard Euler (1707–1783) ii September 4, 2009 14:33 World Scientific Book - 9in x 6in LegacyLeonhard To my wife Sadhana, grandson Kirin,and granddaughter Princess Maya, with love and affection. -
Asymptotic Problems in Number Theory Summary of Lectures- Spring 2015
Math 719: Asymptotic Problems in Number Theory Summary of Lectures- Spring 2015. In this document I will give a summary of what we have covered so far in the course, provide references, and given some idea of where we are headed next. 1 Lecture 1 In the first lecture I gave an overview of what we will cover in the first half of the course. The broad goal is to understand the behavior of families of arithmetic objects. We want to understand what an `average' object looks like, and also what an `extremal' object looks like. We will look at this question in a few different settings. The three main topics will (likely) be: 1. Class groups of imaginary quadratic fields; 2. Curves over finite fields; 3. Linear codes. Our first major goal is to understand positivep definite quadratic forms of given discriminant and then connection to class groups of the field Q( −d), or really more accurately, the quadratic ring of discriminant −d. We will spend approximately the first three weeks setting up this connection, first focusing on quadratic forms and then transferring over to ideal class groups. p As we vary over all quadratic imaginary fields K = Q( −d) where d > 0 is squarefree, we get some set of finite abelian groups C(OK ). What can we say about these groups? How large are they on average? How often is this group trivial? What can we say about the p-parts of these groups for fixed p? Understanding these questions will require using some of the key ideas of class field theory and also understanding some analytic techniques. -
The Class Number Formula for Quadratic Fields and Related Results
The Class Number Formula for Quadratic Fields and Related Results Roy Zhao January 31, 2016 1 The Class Number Formula for Quadratic Fields and Related Results Roy Zhao CONTENTS Page 2/ 21 Contents 1 Acknowledgements 3 2 Notation 4 3 Introduction 5 4 Concepts Needed 5 4.1 TheKroneckerSymbol.................................... 6 4.2 Lattices ............................................ 6 5 Review about Quadratic Extensions 7 5.1 RingofIntegers........................................ 7 5.2 Norm in Quadratic Fields . 7 5.3 TheGroupofUnits ..................................... 7 6 Unique Factorization of Ideals 8 6.1 ContainmentImpliesDivision................................ 8 6.2 Unique Factorization . 8 6.3 IdentifyingPrimeIdeals ................................... 9 7 Ideal Class Group 9 7.1 IdealNorm .......................................... 9 7.2 Fractional Ideals . 9 7.3 Ideal Class Group . 10 7.4 MinkowskiBound....................................... 10 7.5 Finiteness of the Ideal Class Group . 10 7.6 Examples of Calculating the Ideal Class Group . 10 8 The Class Number Formula for Quadratic Extensions 11 8.1 IdealDensity ......................................... 11 8.1.1 Ideal Density in Imaginary Quadratic Fields . 11 8.1.2 Ideal Density in Real Quadratic Fields . 12 8.2 TheZetaFunctionandL-Series............................... 14 8.3 The Class Number Formula . 16 8.4 Value of the Kronecker Symbol . 17 8.5 UniquenessoftheField ................................... 19 9 Appendix 20 2 The Class Number Formula for Quadratic Fields and Related Results Roy Zhao Page 3/ 21 1 Acknowledgements I would like to thank my advisor Professor Richard Pink for his helpful discussions with me on this subject matter throughout the semester, and his extremely helpful comments on drafts of this paper. I would also like to thank Professor Chris Skinner for helping me choose this subject matter and for reading through this paper. -
Dirichlet's Class Number Formula
Dirichlet's Class Number Formula Luke Giberson 4/26/13 These lecture notes are a condensed version of Tom Weston's exposition on this topic. The goal is to develop an analytic formula for the class number of an imaginary quadratic field. Algebraic Motivation Definition.p Fix a squarefree positive integer n. The ring of algebraic integers, O−n ≤ Q( −n) is defined as ( p a + b −n a; b 2 Z if n ≡ 1; 2 mod 4 O−n = p a + b −n 2a; 2b 2 Z; 2a ≡ 2b mod 2 if n ≡ 3 mod 4 or equivalently O−n = fa + b! : a; b 2 Zg; where 8p −n if n ≡ 1; 2 mod 4 < p ! = 1 + −n : if n ≡ 3 mod 4: 2 This will be our primary object of study. Though the conditions in this def- inition appear arbitrary,p one can check that elements in O−n are precisely those elements in Q( −n) whose characteristic polynomial has integer coefficients. Definition. We define the norm, a function from the elements of any quadratic field to the integers as N(α) = αα¯. Working in an imaginary quadratic field, the norm is never negative. The norm is particularly useful in transferring multiplicative questions from O−n to the integers. Here are a few properties that are immediate from the definitions. • If α divides β in O−n, then N(α) divides N(β) in Z. • An element α 2 O−n is a unit if and only if N(α) = 1. • If N(α) is prime, then α is irreducible in O−n .