Expand all Collapse all | Results 151 - 175 of 227 |
151. CJM 2004 (vol 56 pp. 71)
Euclidean Rings of Algebraic Integers Let $K$ be a finite Galois extension of the field of rational numbers
with unit rank greater than~3. We prove that the ring of integers of
$K$ is a Euclidean domain if and only if it is a principal ideal
domain. This was previously known under the assumption of the
generalized Riemann hypothesis for Dedekind zeta functions. We now
prove this unconditionally.
Categories:11R04, 11R27, 11R32, 11R42, 11N36 |
152. CJM 2004 (vol 56 pp. 194)
Selmer Groups of Elliptic Curves with Complex Multiplication Suppose $K$ is an imaginary quadratic field and $E$ is an elliptic curve over a
number field $F$ with complex multiplication by the ring of integers in $K$.
Let $p$ be a rational prime that splits as $\mathfrak{p}_{1}\mathfrak{p}_{2}$
in $K$. Let $E_{p^{n}}$ denote the $p^{n}$-division points on $E$. Assume
that $F(E_{p^{n}})$ is abelian over $K$ for all $n\geq 0$. This paper proves
that the Pontrjagin dual of the $\mathfrak{p}_{1}^{\infty}$-Selmer group of
$E$ over $F(E_{p^{\infty}})$ is a finitely generated free $\Lambda$-module,
where $\Lambda$ is the Iwasawa algebra of $\Gal\bigl(F(E_{p^{\infty}})/
F(E_{\mathfrak{p}_{1}^{\infty}\mathfrak{p}_{2}})\bigr)$. It also gives a simple
formula for the rank of the Pontrjagin dual as a $\Lambda$-module.
Categories:11R23, 11G05 |
153. CJM 2004 (vol 56 pp. 55)
$\mathbb{Z}[\sqrt{14}]$ is Euclidean We provide the first unconditional proof that the ring $\mathbb{Z}
[\sqrt{14}]$ is a Euclidean domain. The proof is generalized to
other real quadratic fields and to cyclotomic extensions of
$\mathbb{Q}$. It is proved that if $K$ is a real quadratic field
(modulo the existence of two special primes of $K$) or if $K$ is a
cyclotomic extension of $\mathbb{Q}$ then:
$$
the~ring~of~integers~of~K~is~a~Euclidean~domain~if~and~only~if~it~is~a~principal~ideal~domain.
$$
The proof is a modification of the proof of a theorem of Clark and
Murty giving a similar result when $K$ is a totally real extension of
degree at least three. The main changes are a new Motzkin-type lemma
and the addition of the large sieve to the argument. These changes
allow application of a powerful theorem due to Bombieri, Friedlander
and Iwaniec in order to obtain the result in the real quadratic case.
The modification also allows the completion of the classification of
cyclotomic extensions in terms of the Euclidean property.
Categories:11R04, 11R11 |
154. CJM 2003 (vol 55 pp. 1191)
Decay of Mean Values of Multiplicative Functions For given multiplicative function $f$, with $|f(n)| \leq 1$ for all
$n$, we are interested in how fast its mean value $(1/x) \sum_{n\leq
x} f(n)$ converges. Hal\'asz showed that this depends on the minimum
$M$ (over $y\in \mathbb{R}$) of $\sum_{p\leq x} \bigl( 1 - \Re (f(p)
p^{-iy}) \bigr) / p$, and subsequent authors gave the upper bound $\ll
(1+M) e^{-M}$. For many applications it is necessary to have explicit
constants in this and various related bounds, and we provide these via
our own variant of the Hal\'asz-Montgomery lemma (in fact the constant
we give is best possible up to a factor of 10). We also develop a new
type of hybrid bound in terms of the location of the absolute value of
$y$ that minimizes the sum above. As one application we give bounds
for the least representatives of the cosets of the $k$-th powers
mod~$p$.
Categories:11N60, 11N56, 10K20, 11N37 |
155. CJM 2003 (vol 55 pp. 897)
Hypergeometric Abelian Varieties In this paper, we construct abelian varieties associated to Gauss' and
Appell--Lauricella hypergeometric series.
Abelian varieties of this kind and the algebraic curves we define
to construct them were considered by several authors in settings
ranging from monodromy groups (Deligne, Mostow), exceptional sets
(Cohen, Wolfart, W\"ustholz), modular embeddings (Cohen, Wolfart) to
CM-type (Cohen, Shiga, Wolfart) and modularity (Darmon).
Our contribution is to provide a complete, explicit and self-contained
geometric construction.
Categories:11, 14 |
156. CJM 2003 (vol 55 pp. 933)
Renormalized Periods on $\GL(3)$ A theory of renormalization of divergent integrals over torus
periods on $\GL(3)$ is given, based on a relative truncation. It
is shown that the renormalized periods of Eisenstein series have
unexpected functional equations.
Categories:11F12, 11F55 |
157. CJM 2003 (vol 55 pp. 711)
Adic Topologies for the Rational Integers A topology on $\mathbb{Z}$, which gives a nice proof that the
set of prime integers is infinite, is characterised and examined.
It is found to be homeomorphic to $\mathbb{Q}$, with a compact
completion homeomorphic to the Cantor set. It has a natural place
in a family of topologies on $\mathbb{Z}$, which includes the
$p$-adics, and one in which the set of rational primes $\mathbb{P}$
is dense. Examples from number theory are given, including the
primes and squares, Fermat numbers, Fibonacci numbers and $k$-free
numbers.
Keywords:$p$-adic, metrizable, quasi-valuation, topological ring,, completion, inverse limit, diophantine equation, prime integers,, Fermat numbers, Fibonacci numbers Categories:11B05, 11B25, 11B50, 13J10, 13B35 |
158. CJM 2003 (vol 55 pp. 673)
A Note on Cyclotomic Euler Systems and the Double Complex Method Let $\FF$ be a finite real abelian extension of $\QQ$. Let $M$ be an odd
positive integer. For every squarefree positive integer $r$ the prime
factors of which are congruent to $1$ modulo $M$ and split completely
in $\FF$, the corresponding Kolyvagin class $\kappa_r\in\FF^{\times}/
\FF^{\times M}$ satisfies a remarkable and crucial recursion which
for each prime number $\ell$ dividing $r$ determines the order of
vanishing of $\kappa_r$ at each place of $\FF$ above $\ell$ in terms
of $\kappa_{r/\ell}$. In this note we give the recursion a new and
universal interpretation with the help of the double complex method
introduced by Anderson and further developed by Das and Ouyang. Namely,
we show that the recursion satisfied by Kolyvagin classes is the
specialization of a universal recursion independent of $\FF$ satisfied
by universal Kolyvagin classes in the group cohomology of the universal
ordinary distribution {\it \`a la\/} Kubert tensored with $\ZZ/M\ZZ$.
Further, we show by a method involving a variant of the diagonal shift
operation introduced by Das that certain group cohomology classes belonging
(up to sign) to a basis previously constructed by Ouyang also satisfy the
universal recursion.
Categories:11R18, 11R23, 11R34 |
159. CJM 2003 (vol 55 pp. 432)
Pair Correlation of Squares in $p$-Adic Fields Let $p$ be an odd prime number, $K$ a $p$-adic field of degree $r$
over $\mathbf{Q}_p$, $O$ the ring of integers in $K$, $B = \{\beta_1,\dots,
\beta_r\}$ an integral basis of $K$ over $\mathbf{Q}_p$, $u$ a unit in $O$
and consider sets of the form $\mathcal{N}=\{n_1\beta_1+\cdots+n_r\beta_r:
1\leq n_j\leq N_j, 1\leq j\leq r\}$. We show under certain growth
conditions that the pair correlation of $\{uz^2:z\in\mathcal{N}\}$ becomes
Poissonian.
Categories:11S99, 11K06, 1134 |
160. CJM 2003 (vol 55 pp. 353)
Weak Explicit Matching for Level Zero Discrete Series of Unit Groups of $\mathfrak{p}$-Adic Simple Algebras |
Weak Explicit Matching for Level Zero Discrete Series of Unit Groups of $\mathfrak{p}$-Adic Simple Algebras Let $F$ be a $p$-adic local field and let $A_i^\times$ be the unit
group of a central simple $F$-algebra $A_i$ of reduced degree $n>1$
($i=1,2$). Let $\mathcal{R}^2 (A_i^\times)$ denote the set of
irreducible discrete series representations of $A_i^\times$. The
``Abstract Matching Theorem'' asserts the existence of a bijection,
the ``Jacquet-Langlands'' map, $\mathcal{J} \mathcal{L}_{A_2,A_1}
\colon \mathcal{R}^2 (A_1^\times) \to \mathcal{R}^2 (A_2^\times)$
which, up to known sign, preserves character values for regular
elliptic elements. This paper addresses the question of explicitly
describing the map $\mathcal{J} \mathcal{L}$, but only for ``level
zero'' representations. We prove that the restriction $\mathcal{J}
\mathcal{L}_{A_2,A_1} \colon \mathcal{R}_0^2 (A_1^\times) \to
\mathcal{R}_0^2 (A_2^\times)$ is a bijection of level zero discrete
series (Proposition~3.2) and we give a parameterization of the set of
unramified twist classes of level zero discrete series which does not
depend upon the algebra $A_i$ and is invariant under $\mathcal{J}
\mathcal{L}_{A_2,A_1}$ (Theorem~4.1).
Categories:22E50, 11R39 |
161. CJM 2003 (vol 55 pp. 292)
Infinitely Divisible Laws Associated with Hyperbolic Functions The infinitely divisible distributions on $\mathbb{R}^+$ of random
variables $C_t$, $S_t$ and $T_t$ with Laplace transforms
$$
\left( \frac{1}{\cosh \sqrt{2\lambda}} \right)^t, \quad \left(
\frac{\sqrt{2\lambda}}{\sinh \sqrt{2\lambda}} \right)^t, \quad \text{and}
\quad \left( \frac{\tanh \sqrt{2\lambda}}{\sqrt{2\lambda}} \right)^t
$$
respectively are characterized for various $t>0$ in a number of
different ways: by simple relations between their moments and
cumulants, by corresponding relations between the distributions and
their L\'evy measures, by recursions for their Mellin transforms, and
by differential equations satisfied by their Laplace transforms. Some
of these results are interpreted probabilistically via known
appearances of these distributions for $t=1$ or $2$ in the description
of the laws of various functionals of Brownian motion and Bessel
processes, such as the heights and lengths of excursions of a
one-dimensional Brownian motion. The distributions of $C_1$ and $S_2$
are also known to appear in the Mellin representations of two
important functions in analytic number theory, the Riemann zeta
function and the Dirichlet $L$-function associated with the quadratic
character modulo~4. Related families of infinitely divisible laws,
including the gamma, logistic and generalized hyperbolic secant
distributions, are derived from $S_t$ and $C_t$ by operations such as
Brownian subordination, exponential tilting, and weak limits, and
characterized in various ways.
Keywords:Riemann zeta function, Mellin transform, characterization of distributions, Brownian motion, Bessel process, LÃ©vy process, gamma process, Meixner process Categories:11M06, 60J65, 60E07 |
162. CJM 2003 (vol 55 pp. 225)
Short Kloosterman Sums for Polynomials over Finite Fields We extend to the setting of polynomials over a finite field certain
estimates for short Kloosterman sums originally due to Karatsuba.
Our estimates are then used to establish some uniformity of
distribution results in the ring $\mathbb{F}_q[x]/M(x)$ for collections of
polynomials either of the form $f^{-1}g^{-1}$ or of the form
$f^{-1}g^{-1}+afg$, where $f$ and $g$ are polynomials coprime to
$M$ and of very small degree relative to $M$, and $a$ is an
arbitrary polynomial. We also give estimates for short Kloosterman
sums where the summation runs over products of two irreducible
polynomials of small degree. It is likely that this result can be
used to give an improvement of the Brun-Titchmarsh theorem for
polynomials over finite fields.
Categories:11T23, 11T06 |
163. CJM 2003 (vol 55 pp. 331)
The Maximum Number of Points on a Curve of Genus $4$ over $\mathbb{F}_8$ is $25$ We prove that the maximum number of rational points on a smooth,
geometrically irreducible genus 4 curve over the field of 8 elements
is 25. The body of the paper shows that 27 points is not possible by
combining techniques from algebraic geometry with a computer
verification. The appendix shows that 26 points is not possible by
examining the zeta functions.
Categories:11G20, 14H25 |
164. CJM 2002 (vol 54 pp. 1202)
Octahedral Galois Representations Arising From $\mathbf{Q}$-Curves of Degree $2$ Generically, one can attach to a $\mathbf{Q}$-curve $C$ octahedral representations
$\rho\colon\Gal(\bar{\mathbf{Q}}/\mathbf{Q})\rightarrow\GL_2(\bar\mathbf{F}_3)$
coming from the Galois action on the $3$-torsion of those abelian varieties of
$\GL_2$-type whose building block is $C$. When $C$ is defined over a quadratic
field and has an isogeny of degree $2$ to its Galois conjugate, there exist
such representations $\rho$ having image into $\GL_2(\mathbf{F}_9)$. Going
the other way, we can ask which $\mod 3$ octahedral representations $\rho$ of
$\Gal(\bar\mathbf{Q}/\mathbf{Q})$ arise from $\mathbf{Q}$-curves in the above
sense. We characterize those arising from quadratic $\mathbf{Q}$-curves of
degree $2$. The approach makes use of Galois embedding techniques in
$\GL_2(\mathbf{F}_9)$, and the characterization can be given in terms of a
quartic polynomial defining the $\mathcal{S}_4$-extension of $\mathbf{Q}$
corresponding to the projective representation $\bar{\rho}$.
Categories:11G05, 11G10, 11R32 |
165. CJM 2002 (vol 54 pp. 1305)
Continued Fractions Associated with $\SL_3 (\mathbf{Z})$ and Units in Complex Cubic Fields Continued fractions associated with $\GL_3 (\mathbf{Z})$ are
introduced and applied to find fundamental units in a two-parameter
family of complex cubic fields.
Keywords:fundamental units, continued fractions, diophantine approximation, symmetric space Categories:11R27, 11J70, 11J13 |
166. CJM 2002 (vol 54 pp. 828)
Spherical Functions for the Semisimple Symmetric Pair $\bigl( \Sp(2,\mathbb{R}), \SL(2,\mathbb{C}) \bigr)$ |
Spherical Functions for the Semisimple Symmetric Pair $\bigl( \Sp(2,\mathbb{R}), \SL(2,\mathbb{C}) \bigr)$ Let $\pi$ be an irreducible generalized principal series
representation of $G = \Sp(2,\mathbb{R})$ induced from its Jacobi parabolic
subgroup. We show that the space of algebraic intertwining operators
from $\pi$ to the representation induced from an irreducible
admissible representation of $\SL(2,\mathbb{C})$ in $G$ is at most one
dimensional. Spherical functions in the title are the images of
$K$-finite vectors by this intertwining operator. We obtain an
integral expression of Mellin-Barnes type for the radial part of our
spherical function.
Categories:22E45, 11F70 |
167. CJM 2002 (vol 54 pp. 673)
Local $L$-Functions for Split Spinor Groups We study the local $L$-functions for Levi subgroups in split spinor
groups defined via the Langlands-Shahidi method and prove a conjecture
on their holomorphy in a half plane. These results have been used in
the work of Kim and Shahidi on the functorial product for $\GL_2
\times \GL_3$.
Category:11F70 |
168. CJM 2002 (vol 54 pp. 449)
ThÃ©orÃ¨me de Vorono\"\i\ dans les espaces symÃ©triques On d\'emontre un th\'eor\`eme de Vorono\"\i\ (caract\'erisation des
maxima locaux de l'invariant d'Hermite) pour les familles de r\'eseaux
param\'etr\'ees par les espaces sym\'etriques irr\'e\-ductibles non
exceptionnels de type non compact.
We prove a theorem of Vorono\"\i\ type (characterisation of local
maxima of the Hermite invariant) for the lattices parametrized by
irreducible nonexceptional symmetric spaces of noncompact type.
Keywords:rÃ©seaux, thÃ©orÃ¨me de Vorono\"\i, espaces symÃ©triques Categories:11H06, 53C35 |
169. CJM 2002 (vol 54 pp. 468)
Mahler's Measure and the Dilogarithm (I) An explicit formula is derived for the logarithmic Mahler measure
$m(P)$ of $P(x,y) = p(x)y - q(x)$, where $p(x)$ and $q(x)$ are
cyclotomic. This is used to find many examples of such polynomials
for which $m(P)$ is rationally related to the Dedekind zeta value
$\zeta_F (2)$ for certain quadratic and quartic fields.
Categories:11G40, 11R06, 11Y35 |
170. CJM 2002 (vol 54 pp. 263)
IntÃ©grales orbitales pondÃ©rÃ©es sur les algÃ¨bres de Lie : le cas $p$-adique Soit $G$ un groupe rÃ©ductif connexe dÃ©fini sur un corps $p$-adique $F$ et $\ggo$
son algÃ¨bre de Lie. Les intÃ©grales orbitales pondÃ©rÃ©es sur $\ggo(F)$ sont des
distributions $J_M(X,f)$---$f$ est une fonction test---indexÃ©es par les
sous-groupes de LÃ©vi $M$ de $G$ et les Ã©lÃ©ments semi-simples rÃ©guliers
$X \in \mgo(F)\cap \ggo_{\reg}$. Leurs analogues sur $G$ sont les principales
composantes du cÃ´tÃ© gÃ©omÃ©trique des formules des traces locale et globale d'Arthur.
Si $M=G$, on retrouve les intÃ©grales orbitales invariantes qui, vues comme fonction
de $X$, sont bornÃ©es sur $\mgo(F)\cap \ggo_{\reg}$~: c'est un rÃ©sultat bien connu
de Harish-Chandra. Si $M \subsetneq G$, les intÃ©grales orbitales pondÃ©rÃ©es
explosent au voisinage des Ã©lÃ©ments singuliers. Nous construisons dans cet article
de nouvelles intÃ©grales orbitales pondÃ©rÃ©es $J_M^b(X,f)$, Ã©gales Ã $J_M(X,f)$ Ã
un terme correctif prÃ¨s, qui tout en conservant les principales propriÃ©tÃ©s des
prÃ©cÃ©dentes (comportement par conjugaison, dÃ©veloppement en germes, {\it etc.})
restent bornÃ©es quand $X$ parcourt $\mgo(F)\cap\ggo_{\reg}$. Nous montrons
Ã©galement que les intÃ©grales orbitales pondÃ©rÃ©es globales, associÃ©es Ã des
Ã©lÃ©ments semi-simples rÃ©guliers, se dÃ©composent en produits de ces nouvelles
intÃ©grales locales.
Categories:22E35, 11F70 |
171. CJM 2002 (vol 54 pp. 417)
Slim Exceptional Sets for Sums of Cubes We investigate exceptional sets associated with various additive
problems involving sums of cubes. By developing a method wherein an
exponential sum over the set of exceptions is employed explicitly
within the Hardy-Littlewood method, we are better able to exploit
excess variables. By way of illustration, we show that the number of
odd integers not divisible by $9$, and not exceeding $X$, that fail to
have a representation as the sum of $7$ cubes of prime numbers, is
$O(X^{23/36+\eps})$. For sums of eight cubes of prime numbers, the
corresponding number of exceptional integers is $O(X^{11/36+\eps})$.
Keywords:Waring's problem, exceptional sets Categories:11P32, 11P05, 11P55 |
172. CJM 2002 (vol 54 pp. 352)
On Connected Components of Shimura Varieties We study the cohomology of connected components of Shimura varieties
$S_{K^p}$ coming from the group $\GSp_{2g}$, by an approach modeled on
the stabilization of the twisted trace formula, due to Kottwitz and
Shelstad. More precisely, for each character $\olomega$ on
the group of connected components of $S_{K^p}$ we define an operator
$L(\omega)$ on the cohomology groups with compact supports $H^i_c
(S_{K^p}, \olbbQ_\ell)$, and then we prove that the virtual
trace of the composition of $L(\omega)$ with a Hecke operator $f$ away
from $p$ and a sufficiently high power of a geometric Frobenius
$\Phi^r_p$, can be expressed as a sum of $\omega$-{\em weighted}
(twisted) orbital integrals (where $\omega$-{\em weighted} means that
the orbital integrals and twisted orbital integrals occuring here each
have a weighting factor coming from the character $\olomega$).
As the crucial step, we define and study a new invariant $\alpha_1
(\gamma_0; \gamma, \delta)$ which is a refinement of the invariant
$\alpha (\gamma_0; \gamma, \delta)$ defined by Kottwitz. This is done
by using a theorem of Reimann and Zink.
Categories:14G35, 11F70 |
173. CJM 2002 (vol 54 pp. 92)
Comparisons of General Linear Groups and their Metaplectic Coverings I We prepare for a comparison of global trace formulas of general linear
groups and their metaplectic coverings. In particular, we generalize
the local metaplectic correspondence of Flicker and Kazhdan and
describe the terms expected to appear in the invariant trace formulas
of the above covering groups. The conjectural trace formulas are
then placed into a form suitable for comparison.
Categories:11F70, 11F72, 22E50 |
174. CJM 2002 (vol 54 pp. 71)
Small Prime Solutions of Quadratic Equations Let $b_1,\dots,b_5$ be non-zero integers and $n$ any integer. Suppose
that $b_1 + \cdots + b_5 \equiv n \pmod{24}$ and $(b_i,b_j) = 1$ for
$1 \leq i < j \leq 5$. In this paper we prove that
\begin{enumerate}[(ii)]
\item[(i)] if $b_j$ are not all of the same sign, then the above
quadratic equation has prime solutions satisfying $p_j \ll \sqrt{|n|}
+ \max \{|b_j|\}^{20+\ve}$; and
\item[(ii)] if all $b_j$ are positive and $n \gg \max \{|b_j|\}^{41+
\ve}$, then the quadratic equation $b_1 p_1^2 + \cdots + b_5 p_5^2 =
n$ is soluble in primes $p_j$.
\end{enumerate}
Categories:11P32, 11P05, 11P55 |
175. CJM 2001 (vol 53 pp. 1194)
Explicit Upper Bounds for Residues of Dedekind Zeta Functions and Values of $L$-Functions at $s=1$, and Explicit Lower Bounds for Relative Class Numbers of $\CM$-Fields |
Explicit Upper Bounds for Residues of Dedekind Zeta Functions and Values of $L$-Functions at $s=1$, and Explicit Lower Bounds for Relative Class Numbers of $\CM$-Fields We provide the reader with a uniform approach for obtaining various
useful explicit upper bounds on residues of Dedekind zeta functions of
numbers fields and on absolute values of values at $s=1$ of $L$-series
associated with primitive characters on ray class groups of number
fields. To make it quite clear to the reader how useful such bounds
are when dealing with class number problems for $\CM$-fields, we
deduce an upper bound for the root discriminants of the normal
$\CM$-fields with (relative) class number one.
Keywords:Dedekind zeta functions, $L$-functions, relative class numbers, $\CM$-fields Categories:11R42, 11R29 |