IRREDUCIBILITY OF ELLIPTIC CURVES AND INTERSECTION WITH LINES.
|
|
- Marcus Gregory
- 5 years ago
- Views:
Transcription
1 IRREDUCIBILITY OF ELLIPTIC CURVES AND INTERSECTION WITH LINES. IAN KIMING 1. Non-singular points and tangents. Suppose that k is a field and that F (x 1,..., x n ) is a homogeneous polynomial in n variables (n 2) with coefficients in k, and of degree d, say. The equation: F (x 1,..., x n ) = 0 defines a projective variety V defined over k. If (ξ 1,..., ξ n ) P n 1 ( k) is a point on V ( k), we say that (ξ 1,..., ξ n ) is nonsingular if the partial derivatives x i do not all vanish at the point. If so, we have a well-defined hyperplane in P n given by the equation: ( ) x x n = 0 ; x 1 x 1=ξ 1 x n x n=ξ n this hyperplane is called the tangent (space) at the point (ξ 1,..., ξ n ). This tangent space does indeed pass through the point (ξ 1,..., ξ n ): For F is a sum with coefficients in k of monomials x i1 1 x in n where i i n = d; such a monomial is seen to give a contribution (i i n ) x i1 1 x in n = d x i1 1 x in n to the left hand side of the tangent equation ( ), whence: ξ ξ n = d F (ξ 1,..., ξ n ) = 0. x 1 x 1=ξ 1 x n x n=ξ n We call V smooth if all points in V ( k) are non-singular. It is clear that the question of whether V contains any singular points is independent of whether we apply a linear change of variables in the equation of V. 2. Elliptic curves. We define (in this course...) an elliptic curve over a field k as a non-singular projective curve given by a general Weierstraß equation: y 2 z + a 1 xyz + a 3 yz 2 = x 3 + a 2 x 2 z + a 4 xz 2 + a 6 z 3. Proposition 1. (i). Assume char(k) 2. Then, using a linear change of variables, a general Weierstraß equation may be put in shape: ( ) y 2 z = x 3 + ax 2 z + bxz 2 + cz 3. 1
2 2 IAN KIMING If additionally char(k) 3, we can also attain a = 0. A Weierstraß equation ( ) defines an elliptic curves if and only if the polynomial x 3 + ax 2 + bx + c does not have any multiple roots. (ii). Assume char(k) = 2. Then, using a linear change of variables, a general Weierstraß equation may be put in shape ( ) y 2 z + a 1 xyz = x 3 + ax 2 z + bxz 2 + cz 3, a 1 0, or ( ) y 2 z + a 3 yz 2 = x 3 + ax 2 z + bxz 2 + cz 3, a 3 0. An equation ( ) defines an elliptic curve if and only if b 2 + a 1 c 0. equation ( ) always defines an elliptic curve. Proof. (i). Since char(k) 2 we can consider the linear change of variables: (x, y, z) (x, y a 1 2 x a 3 2, z) that will bring the Weierstraß equation in shape ( ). If also char(k) 3, we can further consider the change x x a 3, y y, z z. By definition, a Weierstraß equation ( ) defines an elliptic curve if and only if the projective curve defined by it is without singularities. Writing the equation ( ) as F (x, y, z) = 0 where: F (x, y, z) := y 2 z x 3 ax 2 z bxz 2 cz 3, we find that: x = 3x2 2axz bz 2, y = 2yz, z = y2 ax 2 2bxz 3cz 2. Hence, we see that ( x, y, z )(0, 1, 0) = (0, 0, 1), and so O = (0, 1, 0) is never a singular point. Suppose that (x 0, y 0, 1) is an affine singular point. Then 2y 0 = 0, and hence y 0 = 0 since char(k) 2. We conclude that x 0 is a root of x 3 + ax 2 + bx + c. Since we have 3x 2 0 2ax 0 b = 0 we conclude that x 0 is a multiple root of x 3 + ax 2 + bx + c. If conversely the polynomial x 3 +ax 2 +bx+c has a multiple root x 0 then (x 0, 0, 1) is a point on the projective curve defined by ( ). We also see that x and y both vanish at this point. The same holds for the partial derivative z : ax 2 0 2bx 0 3c = (3x ax 0 + b)x 0 3(x ax bx 0 + c) = 0, so that (x 0, 0, 1) is in fact a singular point. (ii). If a 1 0 the linear change of variables (x, y, z) (x + a 3 a 1, y, z) An
3 IRREDUCIBILITY OF ELLIPTIC CURVES AND INTERSECTION WITH LINES. 3 transforms ( ) to an equation of type ( ). The remaining statements are left as exercises. Proposition 2. Suppose that E is an elliptic curve defined over a field k. Then E is irreducible, i.e., does not contain a whole line in P 2 ( k). Proof. We use the previous proposition and leave the proof as an exercise in case char(k) = 2. So assume char(k) 2. According to the previous proposition we may then assume the equation for E in form: E : y 2 z = x 3 + ax 2 z + bxz 2 + cz 3. By definition E is a curve without singularities, and by the previous proposition we know that this is equivalent to the polynomial not having any multiple roots. x 3 + ax 2 + bx + c Now suppose that E contains the line: l: ux + vy + wz = 0, where (u, v, w) k\f(0, 0, 0)g. Suppose that w = 0. Then (u, v) (0, 0). The equation ux + vy = 0 has a solution (x 0, y 0 ) (0, 0). Then l would be the set of points (x 0, y 0, t), t k. But then we would have: 0 = ct 3 + bx 0 t 2 + (ax 2 0 y 2 0)t + x 3 0 for all t k; but that implies first x 3 0 = 0 hence x 0 = 0, and then y 2 0 = ax 2 0 y 2 0 = 0 so y 0 = 0 and contradiction. So we may suppose that l is given by an equation of form z = αx + βy. If now l is contained in E we deduce that the polynomial: g(x, y) := y 2 (αx + βy) x 3 ax 2 (αx + βy) bx(αx + βy) 2 c(αx + βy) 3 vanishes identically. Looking at the coefficients of x 3, xy 2 and x 2 y, respectively, we deduce: (1) cα 3 + bα 2 + aα + 1 = 0, (2) α bβ 2 3cαβ 2 = 0, (3) aβ 2bαβ 3cα 2 β = 0. Then (1) implies α 0; then (2) gives β 0. Then (3) implies a+2bα+3cα 2 = 0. Together with (1) this implies that α 1 is (at least) a double root of the polynomial x 3 + ax 2 + bx + c, contradiction.
4 4 IAN KIMING 3. Intersection between lines and elliptic curves. Let k be a field and let E be an elliptic curve over k given by a Weierstrass equation: We shall write this as: where: y 2 z + a 1 xyz + a 3 yz 2 = x 3 + a 2 x 2 z + a 4 xz 2 + a 6 z 3. F (x, y, z) = 0 F (x, y, z) := y 2 z + a 1 xyz + a 3 yz 2 (x 3 + a 2 x 2 z + a 4 xz 2 + a 6 z 3 ) so that F is a homogeneous polynomial of degree 3. Consider a projective line l given by an equation: αx + βy + γz = 0. Thus, (α, β, γ) (0, 0, 0). Notice that we do not necessarily assume that l is k-rational in the sense that α, β, γ k. The statement we will now discuss is the following: With an appropriately defined notion of multiplicity of intersection points, the line l intersects E in precisely 3 points. Furthermore, if l is k-rational, and if 2 of the intersection points are k-rational then so is the 3 rd point of intersection. Actually, what we describe below is not only a proof of this statement but also an algorithm for computing these intersection points. With the above statement we will not need any reference to Bezout s theorem as in chap. 1 of [1]. The statement above holds of course in much greater generality: Without going into Bezout s theorem, you can at least easily see from the following how to generalize the statement to a statement about points of intersection between a line and a projective curve of degree n (n N); you do need some kind of assumption on the curve though, specifically an irreducibility condition. For us, in connection with elliptic curves it is enough that we showed that an elliptic curve does not contain any line. Now to the argument in favor of the above statement. As we said, the notion of multiplicity will be defined in course of the analysis. One needs to split the discussion up into 3 cases depending on which of α, β, γ is 0. We do only 1 case, assuming that: γ 0. We may thus assume an equation of form: for our line l. z = rx + sy
5 IRREDUCIBILITY OF ELLIPTIC CURVES AND INTERSECTION WITH LINES. 5 and: A point P = (x, y, z) is a point of intersection between l and E precisely if: Thus, if we put: (x, y, z) = (x, y, rx + sy) 0 = F (x, y, z) = F (x, y, rx + sy). g(x, y) := F (x, y, rx + sy), the points of intersection are precisely the points (x, y, rx+sy) where (x, y) (0, 0) is such that g(x, y) = 0 (notice that (x, y, rx + sy) is a point in the projective plane exactly if (x, y) (0, 0)). Now, g(x, y) is clearly a homogeneous polynomial of degree 3, so we can write: ( ) g(x, y) = ax 3 + bx 2 y + cxy 2 + dy 3. Notice that, as the coefficients of F are in k, we can conclude that a, b, c, d are also in k if l is k-rational, i.e., if r, s k. We first claim that g splits into linear factors: ( ) g(x, y) = (u 1 x + v 1 y)(u 2 x + v 2 y)(u 3 x + v 3 y) with u i, v i in an algebraic closure of k and (u i, v i ) (0, 0) for each i = 1, 2, 3. To see this, notice first that g is not identically 0: For otherwise, we would conclude that E contained the whole line l. So if a = d = 0 then (b, c) (0, 0), and also: so that things are clear in this case. g(x, y) = xy(bx + cy) Now, in principle we would have to discuss both of the cases a 0 and d 0. Let us take just the second case: If d 0 the polynomial: ( ) g(1, y) = a + by + cy 2 + dy 3 is a polynomial of degree 3 in y. Hence: g(1, y) = d(y θ 1 )(y θ 2 )(y θ 3 ) with θ 1, θ 2, θ 3 in an algebraic closure of k. Then: d( θ 1 θ 2 θ 3 ) = c, d(θ 1 θ 2 + θ 1 θ 3 + θ 2 θ 3 ) = b, d( θ 1 θ 2 θ 3 ) = a. Using these formulas we see that: ( ) g(x, y) = d(y θ 1 x)(y θ 2 x)(y θ 3 x) simply by multiplying the right hand side out. Thus we have established ( ) in all cases. Using the form ( ) we can now say that the points of intersection between l and E are the points (x 0, y 0, rx 0 + sy 0 ) where (x 0, y 0 ) (0, 0) is a solution to an equation: ( ) u i x 0 + v i y 0 = 0
6 6 IAN KIMING for some i f1, 2, 3g. Now, if (x 0, y 0 ), (x 0, y 0) (0, 0) are 2 solutions to ( ) then (x 0, y 0) = (λx 0, λy 0 ) for some non-zero constant λ: We can deduce this since we had (u i, v i ) (0, 0). Consequently, these 2 solutions to ( ) (for a fixed i) give us the same intersection point (x 0, y 0, rx 0 + sy 0 ) in the projective plane. Or put in another way: We get 3 intersection points by considering the 3 linear factors of g in ( ) one after the other. Of course we may get the same point 2 or even 3 times, but it is now clear how to define multiplicity of an intersection point: It is the number of times the point arises when we consider the linear factors of g one after the other. Concerning the last remark (about k-rational intersection points): Suppose that our line l is k-rational. Then r, s above are in k. Since F has coefficients in k (the elliptic curve E being defined over k) we deduce that a, b, c, d in ( ) and ( ) are in k. Let the 3 points of intersection be (x i, y i, rx i + sy i ), i = 1, 2, 3, corresponding as in the above to solutions to ( ) for i = 1, 2, 3, respectively. Assume now further that the first 2 of these points are k-rational, i.e., that x 1, x 2, y 1, y 2 k. We claim that then the u i, v i in the decomposition ( ) can be chosen in k (the decomposition ( ) is not unique, the factors are only determined up to multiplication with a non-zero constant; clearly we could multiply one of the factors with some non-zero λ and then some other factor with λ 1 ). Let us argue in the case we considered above: If g(x, y) = xy(bx + cy) the claim is clear as b, c k. Suppose then that d 0. Considering ( ) we may choose (say) (u i, v i ) = ( θ i, 1) for i = 1, 2, and (u 3, v 3 ) = ( dθ 3, d). Since (x i, y i ) is a solution (0, 0) to u i x + v i y = 0 we see that we can not possibly have x i = 0. Thus, θ i = y i /x i k for i = 1, 2 by our assumption x 1, x 2, y 1, y 2 k. We deduce: θ 3 = c/d θ 1 θ 2 k and hence the claim u i, v i k for i = 1, 2, 3. But since now u 3, v 3 k the equation u 3 x + v 3 y = 0 has a solution (x 3, y 3) (0, 0) with x 3, y 3 k. As r, s k the point (x 3, y 3, rx 3 + sy 3) is a k-rational point. But this point is the 3 rd point of intersection between l and E. References [1] J. H. Silverman, J. Tate: Rational points on elliptic curves, Undergraduate Texts in Mathematics. Springer, Department of Mathematics, University of Copenhagen, Universitetsparken 5, DK Copenhagen Ø, Denmark. address: kiming@math.ku.dk
LECTURE 7, WEDNESDAY
LECTURE 7, WEDNESDAY 25.02.04 FRANZ LEMMERMEYER 1. Singular Weierstrass Curves Consider cubic curves in Weierstraß form (1) E : y 2 + a 1 xy + a 3 y = x 3 + a 2 x 2 + a 4 x + a 6, the coefficients a i
More informationLECTURE 5, FRIDAY
LECTURE 5, FRIDAY 20.02.04 FRANZ LEMMERMEYER Before we start with the arithmetic of elliptic curves, let us talk a little bit about multiplicities, tangents, and singular points. 1. Tangents How do we
More informationTheorem 6.1 The addition defined above makes the points of E into an abelian group with O as the identity element. Proof. Let s assume that K is
6 Elliptic curves Elliptic curves are not ellipses. The name comes from the elliptic functions arising from the integrals used to calculate the arc length of ellipses. Elliptic curves can be parametrised
More informationProjective Varieties. Chapter Projective Space and Algebraic Sets
Chapter 1 Projective Varieties 1.1 Projective Space and Algebraic Sets 1.1.1 Definition. Consider A n+1 = A n+1 (k). The set of all lines in A n+1 passing through the origin 0 = (0,..., 0) is called the
More informationARITHMETIC IN PURE CUBIC FIELDS AFTER DEDEKIND.
ARITHMETIC IN PURE CUBIC FIELDS AFTER DEDEKIND. IAN KIMING We will study the rings of integers and the decomposition of primes in cubic number fields K of type K = Q( 3 d) where d Z. Cubic number fields
More informationElliptic curves and modularity
Elliptic curves and modularity For background and (most) proofs, we refer to [1]. 1 Weierstrass models Let K be any field. For any a 1, a 2, a 3, a 4, a 6 K consider the plane projective curve C given
More informationElliptic Curves and Public Key Cryptography (3rd VDS Summer School) Discussion/Problem Session I
Elliptic Curves and Public Key Cryptography (3rd VDS Summer School) Discussion/Problem Session I You are expected to at least read through this document before Wednesday s discussion session. Hopefully,
More informationLocal properties of plane algebraic curves
Chapter 7 Local properties of plane algebraic curves Throughout this chapter let K be an algebraically closed field of characteristic zero, and as usual let A (K) be embedded into P (K) by identifying
More informationElliptic Curves Spring 2017 Lecture #5 02/22/2017
18.783 Elliptic Curves Spring 017 Lecture #5 0//017 5 Isogenies In almost every branch of mathematics, when considering a category of mathematical objects with a particular structure, the maps between
More informationLECTURE 10, MONDAY MARCH 15, 2004
LECTURE 10, MONDAY MARCH 15, 2004 FRANZ LEMMERMEYER 1. Minimal Polynomials Let α and β be algebraic numbers, and let f and g denote their minimal polynomials. Consider the resultant R(X) of the polynomials
More informationCORRESPONDENCE BETWEEN ELLIPTIC CURVES IN EDWARDS-BERNSTEIN AND WEIERSTRASS FORMS
CORRESPONDENCE BETWEEN ELLIPTIC CURVES IN EDWARDS-BERNSTEIN AND WEIERSTRASS FORMS DEPARTMENT OF MATHEMATICS AND STATISTICS UNIVERSITY OF OTTAWA SUPERVISOR: PROFESSOR MONICA NEVINS STUDENT: DANG NGUYEN
More informationPOLYNOMIALS. x + 1 x x 4 + x 3. x x 3 x 2. x x 2 + x. x + 1 x 1
POLYNOMIALS A polynomial in x is an expression of the form p(x) = a 0 + a 1 x + a x +. + a n x n Where a 0, a 1, a. a n are real numbers and n is a non-negative integer and a n 0. A polynomial having only
More informationDISCRETE SUBGROUPS, LATTICES, AND UNITS.
DISCRETE SUBGROUPS, LATTICES, AND UNITS. IAN KIMING 1. Discrete subgroups of real vector spaces and lattices. Definitions: A lattice in a real vector space V of dimension d is a subgroup of form: Zv 1
More informationPartial Fractions. Combining fractions over a common denominator is a familiar operation from algebra: 2 x 3 + 3
Partial Fractions Combining fractions over a common denominator is a familiar operation from algebra: x 3 + 3 x + x + 3x 7 () x 3 3x + x 3 From the standpoint of integration, the left side of Equation
More information2.1 Affine and Projective Coordinates
1 Introduction Depending how you look at them, elliptic curves can be deceptively simple. Using one of the easier definitions, we are just looking at points (x,y) that satisfy a cubic equation, something
More informationIntroduction to Arithmetic Geometry
Introduction to Arithmetic Geometry 18.782 Andrew V. Sutherland September 5, 2013 What is arithmetic geometry? Arithmetic geometry applies the techniques of algebraic geometry to problems in number theory
More informationGroup Law for elliptic Curves
Group Law for elliptic Curves http://www.math.ku.dk/ verrill/grouplaw/ (Based on Cassels Lectures on Elliptic curves, Chapter 7) 1 Outline: Introductory remarks Construction of the group law Case of finding
More informationIntroduction to Arithmetic Geometry Fall 2013 Lecture #23 11/26/2013
18.782 Introduction to Arithmetic Geometry Fall 2013 Lecture #23 11/26/2013 As usual, a curve is a smooth projective (geometrically irreducible) variety of dimension one and k is a perfect field. 23.1
More informationCLASSIFYING QUADRATIC QUANTUM P 2 S BY USING GRADED SKEW CLIFFORD ALGEBRAS
CLASSIFYING QUADRATIC QUANTUM P 2 S BY USING GRADED SKEW CLIFFORD ALGEBRAS Manizheh Nafari 1 manizheh@uta.edu Michaela Vancliff 2 vancliff@uta.edu uta.edu/math/vancliff Jun Zhang zhangjun19@gmail.com Department
More informationdiv(f ) = D and deg(d) = deg(f ) = d i deg(f i ) (compare this with the definitions for smooth curves). Let:
Algebraic Curves/Fall 015 Aaron Bertram 4. Projective Plane Curves are hypersurfaces in the plane CP. When nonsingular, they are Riemann surfaces, but we will also consider plane curves with singularities.
More informationMath Midterm Solutions
Math 145 - Midterm Solutions Problem 1. (10 points.) Let n 2, and let S = {a 1,..., a n } be a finite set with n elements in A 1. (i) Show that the quasi-affine set A 1 \ S is isomorphic to an affine set.
More informationThe Group Structure of Elliptic Curves Defined over Finite Fields
The Group Structure of Elliptic Curves Defined over Finite Fields A Senior Project submitted to The Division of Science, Mathematics, and Computing of Bard College by Andrija Peruničić Annandale-on-Hudson,
More informationLINEAR ALGEBRA W W L CHEN
LINEAR ALGEBRA W W L CHEN c W W L Chen, 994, 28. This chapter is available free to all individuals, on the understanding that it is not to be used for financial gain, and may be downloaded and/or photocopied,
More informationBasic facts and definitions
Synopsis Thursday, September 27 Basic facts and definitions We have one one hand ideals I in the polynomial ring k[x 1,... x n ] and subsets V of k n. There is a natural correspondence. I V (I) = {(k 1,
More informationProjective Spaces. Chapter The Projective Line
Chapter 3 Projective Spaces 3.1 The Projective Line Suppose you want to describe the lines through the origin O = (0, 0) in the Euclidean plane R 2. The first thing you might think of is to write down
More informationAN ELEMENTARY PROOF OF THE GROUP LAW FOR ELLIPTIC CURVES
AN ELEMENTARY PROOF OF THE GROUP LAW FOR ELLIPTIC CURVES Abstract. We give a proof of the group law for elliptic curves using explicit formulas. 1. Introduction In the following K will denote an algebraically
More informationMath 203A - Solution Set 4
Math 203A - Solution Set 4 Problem 1. Let X and Y be prevarieties with affine open covers {U i } and {V j }, respectively. (i) Construct the product prevariety X Y by glueing the affine varieties U i V
More informationExercises for algebraic curves
Exercises for algebraic curves Christophe Ritzenthaler February 18, 2019 1 Exercise Lecture 1 1.1 Exercise Show that V = {(x, y) C 2 s.t. y = sin x} is not an algebraic set. Solutions. Let us assume that
More informationFinite affine planes in projective spaces
Finite affine planes in projective spaces J. A.Thas H. Van Maldeghem Ghent University, Belgium {jat,hvm}@cage.ugent.be Abstract We classify all representations of an arbitrary affine plane A of order q
More informationResolution of Singularities in Algebraic Varieties
Resolution of Singularities in Algebraic Varieties Emma Whitten Summer 28 Introduction Recall that algebraic geometry is the study of objects which are or locally resemble solution sets of polynomial equations.
More informationELLIPTIC CURVES BJORN POONEN
ELLIPTIC CURVES BJORN POONEN 1. Introduction The theme of this lecture is to show how geometry can be used to understand the rational number solutions to a polynomial equation. We will illustrate this
More information2. Intersection Multiplicities
2. Intersection Multiplicities 11 2. Intersection Multiplicities Let us start our study of curves by introducing the concept of intersection multiplicity, which will be central throughout these notes.
More informationPOSITIVE POLYNOMIALS LECTURE NOTES (09: 10/05/10) Contents
POSITIVE POLYNOMIALS LECTURE NOTES (09: 10/05/10) SALMA KUHLMANN Contents 1. Proof of Hilbert s Theorem (continued) 1 2. The Motzkin Form 2 3. Robinson Method (1970) 3 3. The Robinson Form 4 1. PROOF OF
More informationPolynomial decompositions and applications
Polynomial decompositions and applications Jarosªaw Buczy«ski 26th October 2014 Tensors Tensors (also referred to as multi-way arrays ) are present both in pure math- ematics and in more applied sciences:
More informationOn Maps Taking Lines to Plane Curves
Arnold Math J. (2016) 2:1 20 DOI 10.1007/s40598-015-0027-1 RESEARCH CONTRIBUTION On Maps Taking Lines to Plane Curves Vsevolod Petrushchenko 1 Vladlen Timorin 1 Received: 24 March 2015 / Accepted: 16 October
More informationIntroduction to Arithmetic Geometry Fall 2013 Lecture #24 12/03/2013
18.78 Introduction to Arithmetic Geometry Fall 013 Lecture #4 1/03/013 4.1 Isogenies of elliptic curves Definition 4.1. Let E 1 /k and E /k be elliptic curves with distinguished rational points O 1 and
More informationExercise Sheet 3 - Solutions
Algebraic Geometry D-MATH, FS 2016 Prof. Pandharipande Exercise Sheet 3 - Solutions 1. Prove the following basic facts about algebraic maps. a) For f : X Y and g : Y Z algebraic morphisms of quasi-projective
More information10. Smooth Varieties. 82 Andreas Gathmann
82 Andreas Gathmann 10. Smooth Varieties Let a be a point on a variety X. In the last chapter we have introduced the tangent cone C a X as a way to study X locally around a (see Construction 9.20). It
More informationFFTs in Graphics and Vision. Homogenous Polynomials and Irreducible Representations
FFTs in Graphics and Vision Homogenous Polynomials and Irreducible Representations 1 Outline The 2π Term in Assignment 1 Homogenous Polynomials Representations of Functions on the Unit-Circle Sub-Representations
More informationTHE RING OF POLYNOMIALS. Special Products and Factoring
THE RING OF POLYNOMIALS Special Products and Factoring Special Products and Factoring Upon completion, you should be able to Find special products Factor a polynomial completely Special Products - rules
More informationAppendix B Convex analysis
This version: 28/02/2014 Appendix B Convex analysis In this appendix we review a few basic notions of convexity and related notions that will be important for us at various times. B.1 The Hausdorff distance
More informationResultants. Chapter Elimination Theory. Resultants
Chapter 9 Resultants 9.1 Elimination Theory We know that a line and a curve of degree n intersect in exactly n points if we work in the projective plane over some algebraically closed field K. Using the
More informationChapter 3. Second Order Linear PDEs
Chapter 3. Second Order Linear PDEs 3.1 Introduction The general class of second order linear PDEs are of the form: ax, y)u xx + bx, y)u xy + cx, y)u yy + dx, y)u x + ex, y)u y + f x, y)u = gx, y). 3.1)
More informationCourse 311: Michaelmas Term 2005 Part III: Topics in Commutative Algebra
Course 311: Michaelmas Term 2005 Part III: Topics in Commutative Algebra D. R. Wilkins Contents 3 Topics in Commutative Algebra 2 3.1 Rings and Fields......................... 2 3.2 Ideals...............................
More informationarxiv: v1 [math.gr] 3 Feb 2019
Galois groups of symmetric sextic trinomials arxiv:1902.00965v1 [math.gr] Feb 2019 Alberto Cavallo Max Planck Institute for Mathematics, Bonn 5111, Germany cavallo@mpim-bonn.mpg.de Abstract We compute
More informationMAS345 Algebraic Geometry of Curves: Exercises
MAS345 Algebraic Geometry of Curves: Exercises AJ Duncan, September 22, 2003 1 Drawing Curves In this section of the exercises some methods of visualising curves in R 2 are investigated. All the curves
More informationTopics In Algebra Elementary Algebraic Geometry
Topics In Algebra Elementary Algebraic Geometry David Marker Spring 2003 Contents 1 Algebraically Closed Fields 2 2 Affine Lines and Conics 14 3 Projective Space 23 4 Irreducible Components 40 5 Bézout
More informationHere, the word cubic designates an algebraic curve C in the projective plane P2 defined by a homogeneous equation, F (X, Y, Z) = 0, of
Chapter 5 Elliptic Curves Mais où sont les neiges d antan? François Villon An elliptic curve can be defined as a smooth projective curve of degree 3 in the projective plane with a distinguished point chosen
More informationElliptic Curves and Public Key Cryptography
Elliptic Curves and Public Key Cryptography Jeff Achter January 7, 2011 1 Introduction to Elliptic Curves 1.1 Diophantine equations Many classical problems in number theory have the following form: Let
More informationINTRODUCTION TO ELLIPTIC CURVES
INTRODUCTION TO ELLIPTIC CURVES MATILDE LALÍN Abstract. These notes correspond to a mini-course taught by the author during the program Two Weeks at Waterloo - A Summer School for Women in Math. Please
More informationCONSTRUCTION OF THE REAL NUMBERS.
CONSTRUCTION OF THE REAL NUMBERS. IAN KIMING 1. Motivation. It will not come as a big surprise to anyone when I say that we need the real numbers in mathematics. More to the point, we need to be able to
More informationIntroduction to Arithmetic Geometry Fall 2013 Lecture #17 11/05/2013
18.782 Introduction to Arithmetic Geometry Fall 2013 Lecture #17 11/05/2013 Throughout this lecture k denotes an algebraically closed field. 17.1 Tangent spaces and hypersurfaces For any polynomial f k[x
More informationElliptic Curves: An Introduction
Elliptic Curves: An Introduction Adam Block December 206 Introduction The goal of the following paper will be to explain some of the history of and motivation for elliptic curves, to provide examples and
More informationALGEBRAIC CURVES. B3b course Nigel Hitchin
ALGEBRAIC CURVES B3b course 2009 Nigel Hitchin hitchin@maths.ox.ac.uk 1 These notes trace a path through material which is covered in more detail in the book for the course which is: F Kirwan, Complex
More informationPermutations and Polynomials Sarah Kitchen February 7, 2006
Permutations and Polynomials Sarah Kitchen February 7, 2006 Suppose you are given the equations x + y + z = a and 1 x + 1 y + 1 z = 1 a, and are asked to prove that one of x,y, and z is equal to a. We
More informationA very simple proof of Pascal s hexagon theorem and some applications
Proc. Indian Acad. Sci. (Math. Sci.) Vol. 120, No. 5, November 2010, pp. 619 629. Indian Academy of Sciences A very simple proof of Pascal s hexagon theorem and some applications NEDELJKO STEFANOVIĆ and
More information1. Algebra 1.5. Polynomial Rings
1. ALGEBRA 19 1. Algebra 1.5. Polynomial Rings Lemma 1.5.1 Let R and S be rings with identity element. If R > 1 and S > 1, then R S contains zero divisors. Proof. The two elements (1, 0) and (0, 1) are
More informationELLIPTIC CURVES OVER FINITE FIELDS
Further ELLIPTIC CURVES OVER FINITE FIELDS FRANCESCO PAPPALARDI #4 - THE GROUP STRUCTURE SEPTEMBER 7 TH 2015 SEAMS School 2015 Number Theory and Applications in Cryptography and Coding Theory University
More informationALGEBRAIC GEOMETRY HOMEWORK 3
ALGEBRAIC GEOMETRY HOMEWORK 3 (1) Consider the curve Y 2 = X 2 (X + 1). (a) Sketch the curve. (b) Determine the singular point P on C. (c) For all lines through P, determine the intersection multiplicity
More informationREDUCTION MODULO p. We will prove the reduction modulo p theorem in the general form as given by exercise 4.12, p. 143, of [1].
REDUCTION MODULO p. IAN KIMING We wll prove the reducton modulo p theorem n the general form as gven by exercse 4.12, p. 143, of [1]. We consder an ellptc curve E defned over Q and gven by a Weerstraß
More informationAlgebraic Varieties. Chapter Algebraic Varieties
Chapter 12 Algebraic Varieties 12.1 Algebraic Varieties Let K be a field, n 1 a natural number, and let f 1,..., f m K[X 1,..., X n ] be polynomials with coefficients in K. Then V = {(a 1,..., a n ) :
More informationConvex Functions and Optimization
Chapter 5 Convex Functions and Optimization 5.1 Convex Functions Our next topic is that of convex functions. Again, we will concentrate on the context of a map f : R n R although the situation can be generalized
More information3 Applications of partial differentiation
Advanced Calculus Chapter 3 Applications of partial differentiation 37 3 Applications of partial differentiation 3.1 Stationary points Higher derivatives Let U R 2 and f : U R. The partial derivatives
More informationTHE ALGEBRAIC GEOMETRY DICTIONARY FOR BEGINNERS. Contents
THE ALGEBRAIC GEOMETRY DICTIONARY FOR BEGINNERS ALICE MARK Abstract. This paper is a simple summary of the first most basic definitions in Algebraic Geometry as they are presented in Dummit and Foote ([1]),
More informationMath 418 Algebraic Geometry Notes
Math 418 Algebraic Geometry Notes 1 Affine Schemes Let R be a commutative ring with 1. Definition 1.1. The prime spectrum of R, denoted Spec(R), is the set of prime ideals of the ring R. Spec(R) = {P R
More informationTorsion Points of Elliptic Curves Over Number Fields
Torsion Points of Elliptic Curves Over Number Fields Christine Croll A thesis presented to the faculty of the University of Massachusetts in partial fulfillment of the requirements for the degree of Bachelor
More informationElliptic Curves and the abc Conjecture
Elliptic Curves and the abc Conjecture Anton Hilado University of Vermont October 16, 2018 Anton Hilado (UVM) Elliptic Curves and the abc Conjecture October 16, 2018 1 / 37 Overview 1 The abc conjecture
More informationRATIONAL POINTS ON CURVES. Contents
RATIONAL POINTS ON CURVES BLANCA VIÑA PATIÑO Contents 1. Introduction 1 2. Algebraic Curves 2 3. Genus 0 3 4. Genus 1 7 4.1. Group of E(Q) 7 4.2. Mordell-Weil Theorem 8 5. Genus 2 10 6. Uniformity of Rational
More informationCOMPLEX MULTIPLICATION: LECTURE 13
COMPLEX MULTIPLICATION: LECTURE 13 Example 0.1. If we let C = P 1, then k(c) = k(t) = k(c (q) ) and the φ (t) = t q, thus the extension k(c)/φ (k(c)) is of the form k(t 1/q )/k(t) which as you may recall
More informationMath 203A - Solution Set 1
Math 203A - Solution Set 1 Problem 1. Show that the Zariski topology on A 2 is not the product of the Zariski topologies on A 1 A 1. Answer: Clearly, the diagonal Z = {(x, y) : x y = 0} A 2 is closed in
More informationPolynomials, Ideals, and Gröbner Bases
Polynomials, Ideals, and Gröbner Bases Notes by Bernd Sturmfels for the lecture on April 10, 2018, in the IMPRS Ringvorlesung Introduction to Nonlinear Algebra We fix a field K. Some examples of fields
More informationTangent spaces, normals and extrema
Chapter 3 Tangent spaces, normals and extrema If S is a surface in 3-space, with a point a S where S looks smooth, i.e., without any fold or cusp or self-crossing, we can intuitively define the tangent
More informationMath 341: Convex Geometry. Xi Chen
Math 341: Convex Geometry Xi Chen 479 Central Academic Building, University of Alberta, Edmonton, Alberta T6G 2G1, CANADA E-mail address: xichen@math.ualberta.ca CHAPTER 1 Basics 1. Euclidean Geometry
More informationElliptic curves and their cryptographic applications
Eastern Washington University EWU Digital Commons EWU Masters Thesis Collection Student Research and Creative Works 2013 Elliptic curves and their cryptographic applications Samuel L. Wenberg Eastern Washington
More informationinv lve a journal of mathematics 2009 Vol. 2, No. 3 Numerical evidence on the uniform distribution of power residues for elliptic curves
inv lve a journal of mathematics Numerical evidence on the uniform distribution of power residues for elliptic curves Jeffrey Hatley and Amanda Hittson mathematical sciences publishers 29 Vol. 2, No. 3
More informationAbelian Varieties and Complex Tori: A Tale of Correspondence
Abelian Varieties and Complex Tori: A Tale of Correspondence Nate Bushek March 12, 2012 Introduction: This is an expository presentation on an area of personal interest, not expertise. I will use results
More informationAlgebraic geometry codes
Algebraic geometry codes Tom Høholdt, Jacobus H. van Lint and Ruud Pellikaan In the Handbook of Coding Theory, vol 1, pp. 871-961, (V.S. Pless, W.C. Huffman and R.A. Brualdi Eds.), Elsevier, Amsterdam
More informationADVANCED TOPICS IN ALGEBRAIC GEOMETRY
ADVANCED TOPICS IN ALGEBRAIC GEOMETRY DAVID WHITE Outline of talk: My goal is to introduce a few more advanced topics in algebraic geometry but not to go into too much detail. This will be a survey of
More informationExamples of numerics in commutative algebra and algebraic geo
Examples of numerics in commutative algebra and algebraic geometry MCAAG - JuanFest Colorado State University May 16, 2016 Portions of this talk include joint work with: Sandra Di Rocco David Eklund Michael
More informationIntroduction to Arithmetic Geometry Fall 2013 Lecture #2 09/10/2013
18.78 Introduction to Arithmetic Geometry Fall 013 Lecture # 09/10/013.1 Plane conics A conic is a plane projective curve of degree. Such a curve has the form C/k : ax + by + cz + dxy + exz + fyz with
More informationLinear Algebra. Hoffman & Kunze. 2nd edition. Answers and Solutions to Problems and Exercises Typos, comments and etc...
Linear Algebra Hoffman & Kunze 2nd edition Answers and Solutions to Problems and Exercises Typos, comments and etc Gregory R Grant University of Pennsylvania email: ggrant@upennedu Julyl 2017 2 Note This
More informationSOLVED PROBLEMS. 1. The angle between two lines whose direction cosines are given by the equation l + m + n = 0, l 2 + m 2 + n 2 = 0 is
SOLVED PROBLEMS OBJECTIVE 1. The angle between two lines whose direction cosines are given by the equation l + m + n = 0, l 2 + m 2 + n 2 = 0 is (A) π/3 (B) 2π/3 (C) π/4 (D) None of these hb : Eliminating
More informationD-MATH Algebraic Geometry FS 2018 Prof. Emmanuel Kowalski. Solutions Sheet 1. Classical Varieties
D-MATH Algebraic Geometry FS 2018 Prof. Emmanuel Kowalski Solutions Sheet 1 Classical Varieties Let K be an algebraically closed field. All algebraic sets below are defined over K, unless specified otherwise.
More informationLECTURE 15, WEDNESDAY
LECTURE 15, WEDNESDAY 31.03.04 FRANZ LEMMERMEYER 1. The Filtration of E (1) Let us now see why the kernel of reduction E (1) is torsion free. Recall that E (1) is defined by the exact sequence 0 E (1)
More informationPure Math 764, Winter 2014
Compact course notes Pure Math 764, Winter 2014 Introduction to Algebraic Geometry Lecturer: R. Moraru transcribed by: J. Lazovskis University of Waterloo April 20, 2014 Contents 1 Basic geometric objects
More informationwhere m is the maximal ideal of O X,p. Note that m/m 2 is a vector space. Suppose that we are given a morphism
8. Smoothness and the Zariski tangent space We want to give an algebraic notion of the tangent space. In differential geometry, tangent vectors are equivalence classes of maps of intervals in R into the
More informationChapter 3 Second Order Linear Equations
Partial Differential Equations (Math 3303) A Ë@ Õæ Aë áöß @. X. @ 2015-2014 ú GA JË@ É Ë@ Chapter 3 Second Order Linear Equations Second-order partial differential equations for an known function u(x,
More informationALGEBRAIC GEOMETRY COURSE NOTES, LECTURE 4: MORE ABOUT VARIETIES AND REGULAR FUNCTIONS.
ALGERAIC GEOMETRY COURSE NOTES, LECTURE 4: MORE AOUT VARIETIES AND REGULAR FUNCTIONS. ANDREW SALCH. More about some claims from the last lecture. Perhaps you have noticed by now that the Zariski topology
More information8. Prime Factorization and Primary Decompositions
70 Andreas Gathmann 8. Prime Factorization and Primary Decompositions 13 When it comes to actual computations, Euclidean domains (or more generally principal ideal domains) are probably the nicest rings
More informationMath 203A - Solution Set 1
Math 203A - Solution Set 1 Problem 1. Show that the Zariski topology on A 2 is not the product of the Zariski topologies on A 1 A 1. Answer: Clearly, the diagonal Z = {(x, y) : x y = 0} A 2 is closed in
More information12. Hilbert Polynomials and Bézout s Theorem
12. Hilbert Polynomials and Bézout s Theorem 95 12. Hilbert Polynomials and Bézout s Theorem After our study of smooth cubic surfaces in the last chapter, let us now come back to the general theory of
More informationDirect Proof Rational Numbers
Direct Proof Rational Numbers Lecture 14 Section 4.2 Robb T. Koether Hampden-Sydney College Thu, Feb 7, 2013 Robb T. Koether (Hampden-Sydney College) Direct Proof Rational Numbers Thu, Feb 7, 2013 1 /
More information1 Flat, Smooth, Unramified, and Étale Morphisms
1 Flat, Smooth, Unramified, and Étale Morphisms 1.1 Flat morphisms Definition 1.1. An A-module M is flat if the (right-exact) functor A M is exact. It is faithfully flat if a complex of A-modules P N Q
More informationAPPLICATIONS The eigenvalues are λ = 5, 5. An orthonormal basis of eigenvectors consists of
CHAPTER III APPLICATIONS The eigenvalues are λ =, An orthonormal basis of eigenvectors consists of, The eigenvalues are λ =, A basis of eigenvectors consists of, 4 which are not perpendicular However,
More information6 Orthogonal groups. O 2m 1 q. q 2i 1 q 2i. 1 i 1. 1 q 2i 2. O 2m q. q m m 1. 1 q 2i 1 i 1. 1 q 2i. i 1. 2 q 1 q i 1 q i 1. m 1.
6 Orthogonal groups We now turn to the orthogonal groups. These are more difficult, for two related reasons. First, it is not always true that the group of isometries with determinant 1 is equal to its
More informationModern Number Theory: Rank of Elliptic Curves
Modern Number Theory: Rank of Elliptic Curves Department of Mathematics University of California, Irvine October 24, 2007 Rank of Outline 1 Introduction Basics Algebraic Structure 2 The Problem Relation
More informationPolynomials. Math 4800/6080 Project Course
Polynomials. Math 4800/6080 Project Course 2. Algebraic Curves. Everyone knows what a curve is, until he has studied enough mathematics to become confused through the countless number of possible exceptions.
More informationu xx + u yy = 0. (5.1)
Chapter 5 Laplace Equation The following equation is called Laplace equation in two independent variables x, y: The non-homogeneous problem u xx + u yy =. (5.1) u xx + u yy = F, (5.) where F is a function
More informationMethod of Lagrange Multipliers
Method of Lagrange Multipliers A. Salih Department of Aerospace Engineering Indian Institute of Space Science and Technology, Thiruvananthapuram September 2013 Lagrange multiplier method is a technique
More information21.4. Engineering Applications of z-transforms. Introduction. Prerequisites. Learning Outcomes
Engineering Applications of z-transforms 21.4 Introduction In this Section we shall apply the basic theory of z-transforms to help us to obtain the response or output sequence for a discrete system. This
More information