The Langlands Program Seminar
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Langlands, Weil, and Local Class Field Theory
LANGLANDS, WEIL, AND LOCAL CLASS FIELD THEORY DAVID SCHWEIN Abstract. The local Langlands conjecture predicts a relationship between Galois repre- sentations and representations of the topological general linear group. In this talk we explain a special case of the program, local class field theory, with a goal towards its nonabelian generalization. One of our main conclusions is that the Galois group should be replaced by a variant called the Weil group. As number theorists, we would like to understand the absolute Galois group ΓQ of Q. It is hard to say briefly why such an understanding would be interesting. But for one, if we understood the open, index-n subgroups of ΓQ then we would understand the number fields of degree n. There are much deeper reasons, related to the geometry of algebraic varieties, why we suspect ΓQ carries deep information, though that is more speculative. One way to study ΓQ is through its n-dimensional complex representations, that is, (con- jugacy classes of) homomorphisms ΓQ ! GLn(C): Starting with a 1967 letter to Weil, Langlands proposed that these representations are related to the representations of a completely different kind of group, the adelic group GLn(AQ). This circle of ideas is known as the Langlands program. The Langlands program over Q turned out to be very difficult. Even today, we cannot properly formulate a precise conjecture. So to get a start on the problem, mathematicians restricted attention to the completions of Q, namely Qp and R, and studied the problem there. As over Q, Langlands conjectured a relationship between n-dimensional Galois rep- resentations ΓQp ! GLn(C) and representations of the group GLn(Qp), as well as an analogous relationship over R. -
Class Numbers of CM Algebraic Tori, CM Abelian Varieties and Components of Unitary Shimura Varieties
CLASS NUMBERS OF CM ALGEBRAIC TORI, CM ABELIAN VARIETIES AND COMPONENTS OF UNITARY SHIMURA VARIETIES JIA-WEI GUO, NAI-HENG SHEU, AND CHIA-FU YU Abstract. We give a formula for the class number of an arbitrary CM algebraic torus over Q. This is proved based on results of Ono and Shyr. As applications, we give formulas for numbers of polarized CM abelian varieties, of connected components of unitary Shimura varieties and of certain polarized abelian varieties over finite fields. We also give a second proof of our main result. 1. Introduction An algebraic torus T over a number field k is a connected linear algebraic group over k such d that T k k¯ isomorphic to (Gm) k k¯ over the algebraic closure k¯ of k for some integer d 1. The class⊗ number, h(T ), of T is by⊗ definition, the cardinality of T (k) T (A )/U , where A≥ \ k,f T k,f is the finite adele ring of k and UT is the maximal open compact subgroup of T (Ak,f ). Asa natural generalization for the class number of a number field, Takashi Ono [18, 19] studied the class numbers of algebraic tori. Let K/k be a finite extension and let RK/k denote the Weil restriction of scalars form K to k, then we have the following exact sequence of tori defined over k 1 R(1) (G ) R (G ) G 1, −→ K/k m,K −→ K/k m,K −→ m,k −→ where R(1) (G ) is the kernel of the norm map N : R (G ) G . -
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. -
Weil Groups and $ F $-Isocrystals
Weil groups and F -Isocrystals Richard Crew The University of Florida December 19, 2017 Introduction The starting point for local class field theory in most modern treatments is the classification of central simple algebras over a local field K. On the other hand an old theorem of Dieudonn´e[6] may interpreted as saying that when K is absolutely unramified and of characteristic zero any such algebra is the endomorphism algebra of an isopentic F -isocrystal on the completion Knr of a maximal unramified extension of K. In fact the restrictions on K can be removed by a suitably generalizing the notion of F -isocrystal, so one is led to ask if there approach to local class field theory based on the structure theory of F -isocrystals. One aim of this article is to carry out this project, and we will find that it gives a particularly quick approach to most of the main results of local class field theory, the exception being the existence theorem. We will not need many of the more technical results of group cohomology such as the Tate-Nakayama theorem or the “ugly lemma” of [4, Ch. 6 §1.5], and the formal properties of the norm residue symbol follow from the construction rather than the usual cohomological formalism. In this approach one sees a close relation between two topics not normally associated with each other. The first is a celebrated formula of Dwork for the norm residue symbol in the case of a totally ramified abelian extension. A generalization of Dwork’s formula valid for any finite Galois extension can be unearthed from the exercises in chapter XIII of [10]. -
On Functional Equations of Euler Systems
ON FUNCTIONAL EQUATIONS OF EULER SYSTEMS DAVID BURNS AND TAKAMICHI SANO Abstract. We establish precise relations between Euler systems that are respectively associated to a p-adic representation T and to its Kummer dual T ∗(1). Upon appropriate specialization of this general result, we are able to deduce the existence of an Euler system of rank [K : Q] over a totally real field K that both interpolates the values of the Dedekind zeta function of K at all positive even integers and also determines all higher Fitting ideals of the Selmer groups of Gm over abelian extensions of K. This construction in turn motivates the formulation of a precise conjectural generalization of the Coleman-Ihara formula and we provide supporting evidence for this conjecture. Contents 1. Introduction 1 1.1. Background and results 1 1.2. General notation and convention 4 2. Coleman maps and local Tamagawa numbers 6 2.1. The local Tamagawa number conjecture 6 2.2. Coleman maps 8 2.3. The proof of Theorem 2.3 10 3. Generalized Stark elements and Tamagawa numbers 13 3.1. Period-regulator isomorphisms 13 3.2. Generalized Stark elements 16 3.3. Deligne-Ribet p-adic L-functions 17 3.4. Evidence for the Tamagawa number conjecture 18 arXiv:2003.02153v1 [math.NT] 4 Mar 2020 4. The functional equation of vertical determinantal systems 18 4.1. Local vertical determinantal sytems 19 4.2. The functional equation 20 5. Construction of a higher rank Euler system 24 5.1. The Euler system 25 5.2. The proof of Theorem 5.2 26 6. -
On the Non-Abelian Global Class Field Theory
See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/268165110 On the non-abelian global class field theory Article · September 2013 DOI: 10.1007/s40316-013-0004-9 CITATION READS 1 19 1 author: Kazım Ilhan Ikeda Bogazici University 15 PUBLICATIONS 28 CITATIONS SEE PROFILE Some of the authors of this publication are also working on these related projects: The Langlands Reciprocity and Functoriality Principles View project All content following this page was uploaded by Kazım Ilhan Ikeda on 10 January 2018. The user has requested enhancement of the downloaded file. On the non-abelian global class field theory Kazımˆ Ilhan˙ Ikeda˙ –Dedicated to Robert Langlands for his 75th birthday – Abstract. Let K be a global field. The aim of this speculative paper is to discuss the possibility of constructing the non-abelian version of global class field theory of K by “glueing” the non-abelian local class field theories of Kν in the sense of Koch, for each ν ∈ hK, following Chevalley’s philosophy of ideles,` and further discuss the relationship of this theory with the global reciprocity principle of Langlands. Mathematics Subject Classification (2010). Primary 11R39; Secondary 11S37, 11F70. Keywords. global fields, idele` groups, global class field theory, restricted free products, non-abelian idele` groups, non-abelian global class field theory, ℓ-adic representations, automorphic representations, L-functions, Langlands reciprocity principle, global Langlands groups. 1. Non-abelian local class field theory in the sense of Koch For details on non-abelian local class field theory (in the sense of Koch), we refer the reader to the papers [21, 23, 24, 50] as well as Laubie’s work [37]. -
Questions and Remarks to the Langlands Program
Questions and remarks to the Langlands program1 A. N. Parshin (Uspekhi Matem. Nauk, 67(2012), n 3, 115-146; Russian Mathematical Surveys, 67(2012), n 3, 509-539) Introduction ....................................... ......................1 Basic fields from the viewpoint of the scheme theory. .............7 Two-dimensional generalization of the Langlands correspondence . 10 Functorial properties of the Langlands correspondence. ................12 Relation with the geometric Drinfeld-Langlands correspondence . 16 Direct image conjecture . ...................20 A link with the Hasse-Weil conjecture . ................27 Appendix: zero-dimensional generalization of the Langlands correspondence . .................30 References......................................... .....................33 Introduction The goal of the Langlands program is a correspondence between representations of the Galois groups (and their generalizations or versions) and representations of reductive algebraic groups. The starting point for the construction is a field. Six types of the fields are considered: three types of local fields and three types of global fields [L3, F2]. The former ones are the following: 1) finite extensions of the field Qp of p-adic numbers, the field R of real numbers and the field C of complex numbers, arXiv:1307.1878v1 [math.NT] 7 Jul 2013 2) the fields Fq((t)) of Laurent power series, where Fq is the finite field of q elements, 3) the field of Laurent power series C((t)). The global fields are: 4) fields of algebraic numbers (= finite extensions of the field Q of rational numbers), 1I am grateful to R. P. Langlands for very useful conversations during his visit to the Steklov Mathematical institute of the Russian Academy of Sciences (Moscow, October 2011), to Michael Harris and Ulrich Stuhler, who answered my sometimes too naive questions, and to Ilhan˙ Ikeda˙ who has read a first version of the text and has made several remarks. -
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. -
The Local Langlands Correspondence for Tamely Ramified
Introduction to Local Langlands Local Langlands for Tamely Ramified Unitary Groups The Local Langlands Correspondence for tamely ramified groups David Roe Department of Mathematics Harvard University Harvard Number Theory Seminar David Roe The Local Langlands Correspondence for tamely ramified groups Introduction to Local Langlands Local Langlands for Tamely Ramified Unitary Groups Outline 1 Introduction to Local Langlands Local Langlands for GLn Beyond GLn DeBacker-Reeder 2 Local Langlands for Tamely Ramified Unitary Groups The Torus The Character Embeddings and Induction David Roe The Local Langlands Correspondence for tamely ramified groups Local Langlands for GL Introduction to Local Langlands n Beyond GL Local Langlands for Tamely Ramified Unitary Groups n DeBacker-Reeder What is the Langlands Correspondence? A generalization of class field theory to non-abelian extensions. A tool for studying L-functions. A correspondence between representations of Galois groups and representations of algebraic groups. David Roe The Local Langlands Correspondence for tamely ramified groups Local Langlands for GL Introduction to Local Langlands n Beyond GL Local Langlands for Tamely Ramified Unitary Groups n DeBacker-Reeder Local Class Field Theory Irreducible 1-dimensional representations of WQp Ù p q Irreducible representations of GL1 Qp The 1-dimensional case of local Langlands is local class field theory. David Roe The Local Langlands Correspondence for tamely ramified groups Local Langlands for GL Introduction to Local Langlands n Beyond GL Local Langlands for Tamely Ramified Unitary Groups n DeBacker-Reeder Conjecture Irreducible n-dimensional representations of WQp Ù Irreducible representations of GLnpQpq In order to make this conjecture precise, we need to modify both sides a bit. -
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 .