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U-M-I MICROFILMED 1994 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. Broken or indistinct print, colored or poor quality illustrations and photographs, print bleedthrough, substandard margins, and improper alignment can adversely affect reproduction. In the unlikely, event that the author did not send UMI a complete manuscript and there are missing pages, these will be noted. Also, if unauthorized copyright material had to be removed, a note will indicate the deletion. Oversize materials (e.g., maps, drawings, charts) are reproduced by sectioning the original, beginning at the upper left-hand corner and continuing from left to right in equal sections with small overlaps. Each original is also photographed in one exposure and is included in reduced form at the bade of the book. Photographs induded in the original manuscript have been reproduced xerographically in this copy. Higher quality 6" x 9" black and white photographic prints are available for any photographs or illustrations appearing in this copy for an additional charge. Contact UMI directly to order. UMI University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road. Ann Arbor. Ml 48106-1346 USA 313/761-4700 800/521-0600 Order Number 04209G0 On the M2-part” of the Birch and Swlnnerton-Dyer Conjecture for elliptic curves with complex multiplication Gonzalez-Aviles, Cristian D., Ph.D. The Ohio State University, 1004 UMI 300 N. Zeeb Rd. Ann Aibor, MI 48106 O n t h e “2 - p a r t ” o f t h e B ir c h a n d S w i n n e r t o n -D y e r c o n j e c t u r e f o r ELLIPTIC CURVES WITH COMPLEX MULTIPLICATION DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Cristian D. Gonzalez-Aviles, * * * * * The Ohio State University 1994 Dissertation Committee: Approved by Professor Karl Rubin Professor Robert Gold Adviser Professor Warren Sinnott Department of Mathematics A cknowledgements I thank my advisor Prof. Karl Rubin for his guidance and help; 1 have been very fortunate to be able to share in his wisdom and superb talent. My thanks go to Prof. Warren Sinnott as well, who helped me overcome many of the technical difficulties involved in this work. I also benefited from conversations with Professor Robert Gold and Mr. Cristian Popcscu. I thank them heartily for their help. Eslc trabajo csta dcdicado a mis queridos padres , quicncs me han apoyado sicmpre. V it a June 25, 1961 ...............Born in Arica, Chile. 1985 ...............................B. Sc., Univcrsidad dc Chile, Santiago, Chile. 1986 ...............................M. Sc., Univcrsidad dc Chile, Santiago, Chile. Thesis: “Class numbers of quadratic function fields and continued fractions” (J. Number Theory 40, no. 1, January 1992, pp. 38*59). Thesis advisor: Prof. Ricardo Bacza. 1987-1994 .................... Graduate Teaching Associate, Department of Mathematics, The Ohio State University, Columbus, Ohio. F i e l d s o f S t u d y Major Field: Mathematics T a b l e o f C o n t e n t s ACKNOWLEDGEMENTS ........................................................................................ ii VITA ............................................................................................................................... iii CHAPTER PAGE I Introduction ............................................................................................................ I II The primes of bad reduction ............................................................................... 5 2.1 Preliminaries for Chapter II ...................................................................... 5 2.2 Sclmcr groups ............................................................................................... 8 2.3 Sclmer groups, continued ........................................................................... 11 III The “main conjecture” of Iwasawa t h e o r y ..................................................... 18 3.1 Preliminaries for Chapter III .................................................................... 18 3.2 Elliptic units ................................................................... 21 3.3 Euler systems of elliptic units ................................................................... 26 3.4 A logarithm map ......................................................................................... 29 3.5 Statement of the main conjecture ............................................................ 33 3.6 Results from Iwasawa theory. ................................................................. 35 3.7 Iwasawa modules of global and elliptic units ......................................... 39 3.8 A divisibility relation .................................................................................. 44 3.9 The Iwasawa invariants of X * ................................................................. 54 3.10 The Iwasawa invariants of the p>adic L-function. Proof of the main conjecture ...................................................................................................... 60 iv IV The Birch and Swinnerton-Dyer conjecture ..................................................... 67 4.1 The conjecture over A' ................................................................................... 67 4.2 The conjecture over Q ..................................... 71 BIBLIOGRAPHY ........................................................................................................ 79 v C H A PT E R I Introduction Let E be an elliptic curve defined over K — Q (\/—7) (one of the 9 imaginary quadratic fields of class number 1), with complex multiplication by the ring of integers Ok of K and with minimal period lattice generated by SI € Cx. Suppose that L (E fK , 1) ^ 0. Then E(K) is finite (Coates and Wiles [8]) and the Talc-Shafarcvich group ]M{EjK} is finite (Rubin [22]). Further, for each prime q of J(t let Cq = [E(I<q) : £b(/fq)], where Eo(Kq) C E(K q) is the subgroup of points with non-singular reduction modulo q. In this dissertation we prove the following Theorem A. If E has good reduction at 2 then L(E/I<, 1) = m i. (# £ (/0 )-2 m• ( E / K ) • n^q. (1.1) q In other words, the full Birch and Swinnerton-Dyer conjecture is true for E. Remarks, (a) Rubin [23] has shown that (1.1) is true up to multiplication by an element of K divisible only by primes dividing #0% (for all 9 imaginary quadratic fields K of class number 1). Thus when 0j[* = { ± 1} (as is the case for K — Q (\/—7)), the verification of (1.1) reduces, in a sense to be made precise shortly, to “checking 2-components”. The case K — Q (\/—7) treated in this paper is, for reasons that are explained below, the simplest of all. 2 (b) With more work it should be possible to remove the restriction on E in The orem A. We hope to be able to resolve this issue in the near future. (c) Other authors have addressed the problem studied in this dissertation. Sec [1] and [11]. The effectiveness of their methods is limited to those cases where the elliptic curve in question has few primes of bad reduction (at most 2). We hasten to remark, however, that the first of .the references given addresses this problem for other choices of K as well. This author is currently working on these remaining cases. In this thesis wc also prove the following result. For any non-zero integer d let Ed denote the elliptic curve y2 = x3 -f-21dx3 + 112d3x, which has complex multiplication by Ok = Z[(l + V=7)/2). Theorem B. Suppose d — l(m od4) and L(Ed/Q t 1) / 0. Then the full Birch and Swinnerton-Dyer conjecture is true for Ed/Q. The following is a brief outline of the paper. Fix, once and for all, an embedding of K = Q(\/-7) in C. Assume that E has good reduction at 2 and L (E /K t 1) ^ 0, and let B denote the set of primes of K where E has a bad reduction. We will sec below (Proposition 2.1.7) that cq = 4 for each q € B. Further, let 4> denote the Heckc character of K attached to E and 2/(tf>,s) the corresponding Hecke //-function. Then the //-function of E over K factors as L(E/K , s) = L{4>y s)L{$t s) (1.2) and L(4i, l)/Q € J<> so L{E/K, l)/fm = Nk/q(Z,(& l)/«) € Q+. Thus formula (1.1) is true up to multiplication by a power of 2 (cf. Remark (a) above), and therefore Theorem A is equivalent to the statement that L (E /K }l)/SlO, and 46*(^£?(/C)3»)*'a* 3 # m 2°° differ by a 2-adic unit. Here b = #B. Since 2 splits in K , say 2 = pp with p ^ p, one can show, using the factorization (1,2) and the fact that = 4 (Corollary 2.1.2), that the result sought will follow from l(0,l)/ft - 2t-2.#UIp» (1.3) where ~ means “equal up to a unit of /fp”. To establish (1.3) we first show (in §2.3) that #Hom(-Voo, Ep«>)** = 2h~2 • #£(/fp)p- • #UIP« (1.4) where A',*, is the Galois group of the maximal abelian 2-extension of = K(Ep«>) which is unramificd away from the prime above p, and *£ = Gal(KcafE). The essential ingredient in the derivation of this result is Theorem 2.2.6 below, which gives the index of the p°°-Sclmcr group of E in the larger group of 1-cohomology classes which arc locally trivial outside of B U {p}. The proof of Theorem 2.2.6 depends crucially on work of Bashmakov [2]. The rest of the argument leading to (1.4) is likely to seem familiar to those readers acquainted with Coates' paper [6] (but also a little more complicated, because here we deal with the troublesome prime 2). Now Rubin ([23], §11) has shown how to relate the integer on the left-hand side of formula (1.4) to ordp(Xf($, l)/fl) when p^f 2, as an application of Theorem 4.1 of [23], the “main conjecture" of Iwasawa theory for K . In Chapter III we prove a “main conjecture" for the extension KoojK (Theorem 3.5.1 below) which is well-suited for similar applications. The fact that 2 splits in I( means that we are in the setting of a one-variable main conjecture, which is the reason why the case K = Q (\/—7) is the 4 simplest of ail.