Browsing by Author "González Rovira, Josep"

Automorphism group of split Cartan modular curves
González Rovira, Josep (20160801)
Article
Open Access 
Constraints on the automorphism group of a curve
González Rovira, Josep (20170101)
Article
Open AccessFor a curve of genus > 1 defined over a finite field, we present a sufficient criterion for the nonexistence of automorphisms of order a power of a rational prime. We show how this criterion can be used to determine the ... 
Cropping Euler factors of modular Lfunctions
González Rovira, Josep; Jiménez Urroz, Jorge; Lario Loyo, Joan Carles (201309)
Article
Open AccessAccording to the Birch and SwinnertonDyer conjectures, if A/Q is an abelian variety, then its Lfunction must capture a substantial part of the properties of A. The smallest number field L where A has all its endomorphisms ... 
Equations of bielliptic modular curves
González Rovira, Josep (201211)
Article
Open AccessWe give a procedure to determine equations for the modular curves X0(N) which are bielliptic and equations for the 30 values of N such that X0(N) is bielliptic and nonhyperelliptic are presented. 
Frobenius distribution for quotients of Fermat curves of prime exponent
Fité, Francesc; González Rovira, Josep; Lario Loyo, Joan Carles (20150618)
Article
Open AccessLet C denote the Fermat curve over Q of prime exponent l. The Jacobian Jac(C) of C splits over Q as the product of Jacobians Jac(C_k), 0< k < l1, where C_k are curves obtained as quotients of C by certain subgroups of ... 
Functions and differentials on the nonsplit Cartan modular curve of level 11
Fernández González, Julio; González Rovira, Josep (20170101)
Article
Open AccessThe genus 4 modular curve Xns(11) attached to a nonsplit Cartan group of level 11 admits a model defined over Q. We compute generators for its function field in terms of Siegel modular functions. We also show that its ... 
Nonexistence of almost Moore digraphs of diameter four
Conde Colom, Josep; Gimbert Quintilla, Joan; González Rovira, Josep; Miret Biosca, Josep Maria; Moreno Chiral, Ramiro (20130331)
Article
Open AccessRegular digraphs of degree d > 1, diameter k > 1 and order N(d; k) = d+ +dk will be called almost Moore (d; k)digraphs. So far, the problem of their existence has only been solved when d = 2; 3 or k = 2; 3. In this ... 
On the nonexistence of almost Moore digraphs
Conde Colom, Josep; Gimbert Quintilla, Joan; González Rovira, Josep; Miller, Mirka; Miret Biosca, Josep Maria (20140701)
Article
Restricted access  publisher's policyDigraphs of maximum outdegree at most d > 1, diameter at most k > 1 and order N(d, k) = d + ... + d(k) are called almost Moore or (d, k)digraphs. So far, the problem of their existence has been solved only when d = 2, 3 ... 
The automorphism group of the nonsplit Cartan modular curve of level 11
Dose, Valerio; Fernández González, Julio; González Rovira, Josep; Schoof, Rene (20141101)
Article
Restricted access  publisher's policyWe derive equations for the modular curve Xns(11) associated to a nonsplit Cartan subgroup of GL(2)(F11). This allows us to compute the automorphism group of the curve and show that it is isomorphic to Klein's four ... 
The Frobenius traces distribution for modular Abelian surfaces
González Rovira, Josep (201402)
Article
Restricted access  publisher's policyWe prove that there exist at least 15 pairs of measures for which the two normalized Frobenius traces on modular Abelian surfaces are equidistributed. Under an assumption about stochastic independence, we prove that there ... 
The kernel of Ribet’s isogeny for genus three Shimura curves
Molina Blanco, Santiago; González Rovira, Josep (2015)
Article
Open AccessThere are exactly nine reduced discriminants D of indefinite quaternion algebras over Q for which the Shimura curve XD attached to D has genus 3. We present equations for these nine curves. Moreover, for each D we determine ...