The Root Numbers of the Cyclotomic Field of the l-th Roots of Unity

Author(s):  
David Hilbert
1999 ◽  
Vol 42 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Josep González

AbstractWe study the splitting of Fermat Jacobians of prime degree l over an algebraic closure of a finite field of characteristic p not equal to l. We prove that their decomposition is determined by the residue degree of p in the cyclotomic field of the l-th roots of unity. We provide a numerical criterion that allows to compute the absolutely simple subvarieties and their multiplicity in the Fermat Jacobian.


2006 ◽  
Vol 05 (04) ◽  
pp. 403-416
Author(s):  
MANUEL FRANCO-FERNANDEZ ◽  
VICTOR SNAITH

Let K be a p-adic local field where p is an odd prime and let A be the unique quaternion division algebra whose centre is K. By means of Stiefel–Whitney classes, we define an exponential homomorphism ϒK from the orthogonal representations of A*/K* to fourth roots of unity. We then evaluate this homomorphism in terms of the local root numbers of two-dimensional symplectic Galois representations of K, using the Langlands correspondence relating Galois representations to continuous representations of A*.


2012 ◽  
Vol 92 (3) ◽  
pp. 299-311 ◽  
Author(s):  
JOE BUHLER ◽  
STEVE BUTLER ◽  
WARWICK DE LAUNEY ◽  
RON GRAHAM

AbstractMotivated by mathematical aspects of origami, Erik Demaine asked which points in the plane can be constructed by using lines whose angles are multiples of $\pi /n$ for some fixed $n$. This has been answered for some specific small values of $n$ including $n=3,4,5,6,8,10,12,24$. We answer this question for arbitrary $n$. The set of points is a subring of the complex plane $\mathbf {C}$, lying inside the cyclotomic field of $n$th roots of unity; the precise description of the ring depends on whether $n$is prime or composite. The techniques apply in more general situations, for example, infinite sets of angles, or more general constructions of subsets of the plane.


1991 ◽  
Vol 43 (5) ◽  
pp. 1055-1064 ◽  
Author(s):  
Walter Tautz ◽  
Jaap Top ◽  
Alain Verberkmoes

AbstractThe aim of this paper is to present a very explicit construction of one parameter families of hyperelliptic curves C of genus (p−1 )/ 2, for any odd prime number p, with the property that the endomorphism algebra of the jacobian of C contains the real subfield Q(2 cos(2π/p)) of the cyclotomic field Q(e2π i/p).Two proofs of the fact that the constructed curves have this property will be given. One is by providing a double cover with the pth roots of unity in its automorphism group. The other is by explicitly writing down equations of a correspondence in C x C which defines multiplication by 2cos(2π/ p) on the jacobian of C. As a byproduct we obtain polynomials which define bijective maps Fℓ → Fℓ for all prime numbers in certain congruence classes.


2012 ◽  
Vol 08 (03) ◽  
pp. 715-748 ◽  
Author(s):  
KAMAL KHURI-MAKDISI

Let ℓ ≥ 3. Using the moduli interpretation, we define certain elliptic modular forms of level Γ(ℓ) over any field k where 6ℓ is invertible and k contains the ℓth roots of unity. These forms generate a graded algebra [Formula: see text], which, over C, is generated by the Eisenstein series of weight 1 on Γ(ℓ). The main result of this article is that, when k = C, the ring [Formula: see text] contains all modular forms on Γ(ℓ) in weights ≥ 2. The proof combines algebraic and analytic techniques, including the action of Hecke operators and nonvanishing of L-functions. Our results give a systematic method to produce models for the modular curve X(ℓ) defined over the ℓth cyclotomic field, using only exact arithmetic in the ℓ-torsion field of a single Q-rational elliptic curve E0.


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