F. Andreatta, University Degli Studi, Padova, Italy,
and E. Z. Goren, McGill University, Montreal, PQ, Canada

Hilbert Modular Forms: mod p and p-Adic Aspects

Description

We study Hilbert modular forms in characteristic p and over p-adic rings. In the characteristic p theory we describe the kernel and image of the q-expansion map and prove the existence of filtration for Hilbert modular forms; we define operators U, V and Theta_chi and study the variation of the filtration under these operators. Our methods are geometric - comparing holomorphic Hilbert modular forms with rational functions on a moduli scheme with level-p structure, whose poles are supported on the non-ordinary locus.

In the p-adic theory we study congruences between Hilbert modular forms. This applies to the study of congruences between special values of zeta functions of totally real fields. It also allows us to define p-adic Hilbert modular forms "a la Serre" as p-adic uniform limit of classical modular forms, and compare them with p-adic modular forms "a la Katz" that are regular functions on a certain formal moduli scheme. We show that the two notions agree for cusp forms and for a suitable class of weights containing all the classical ones. We extend the operators V and Theta_chi to the p-adic setting.

Contents

Introduction
Notations
Moduli spaces of abelian varieties with real multiplication
Properties of mathcal{G}
Hilbert modular forms
The q-expansion map
The partial Hasse invariants
Reduceness of the partial Hasse invariants
A compactification of mathfrak{M} (k,mu_{pN})^{rm{Kum}}
Congruences mod p^n and Serre's p-adic modular forms
Katz's p-adic Hilbert modular forms
The operators Theta_{mathfrak{P},i}
The operator V
The operator U
Applications to filtrations of modular forms
Theta cycles and parallel filtration (inert case)
Functorialities
Integrality and congruences for values of zeta functions
Numerical examples
Comments regarding values of zeta functions
References

Details:

Series: Memoirs of the American Mathematical Society, Volume: 819
Publication Year: 2005
ISBN: 0-8218-3609-9
Paging: 100 pp.
Binding: Softcover

Javier Fernandez de Bobadilla, Universiteit Utrecht, Netherlands

Moduli Spaces of Polynomials in Two Variables

Description

In the space of polynomials in two variables mathbb{C}[x,y] with complex coefficients we let the group of automorphisms of the affine plane mathbb{A}^2_{mathbb{C}} act by composition on the right. In this paper we investigate the geometry of the orbit space.

We associate a graph with each polynomial in two variables that encodes part of its geometric properties at infinity; we define a partition of mathbb{C}[x,y] imposing that the polynomials in the same stratum are the polynomials with a fixed associated graph. The graphs associated with polynomials belong to certain class of graphs (called behaviour graphs), that has a purely combinatorial definition. We show that any behaviour graph is actually a graph associated with a polynomial. Using this we manage to give a quite precise geometric description of the subsets of the partition.

We associate a moduli functor with each behaviour graph of the class, which assigns to each scheme T the set of families of polynomials with the given graph parametrized over T. Later, using the language of groupoids, we prove that there exists a geometric quotient of the subsets of the partition associated with the given graph by the equivalence relation induced by the action of Aut(mathbb{C}^2). This geometric quotient is a coarse moduli space for the moduli functor associated with the graph. We also give a geometric description of it based on the combinatorics of the associated graph.

The results presented in this memoir need the development of a certain combinatorial formalism. Using it we are also able to reprove certain known theorems in the subject.

Contents

Introduction
Automorphisms of the affine plane
A partition on mathbb{C}[x,y]
The geometry of the partition
The action of Aut(mathbb{C}^2) on mathbb{C}[x,y]
The moduli problem
The moduli spaces
Appendix A. Canonical orders
Bibliography

Details:

Series: Memoirs of the American Mathematical Society, Volume: 817
Publication Year: 2005
ISBN: 0-8218-3593-9
Paging: 136 pp.
Binding: Softcover

Tom De Medts, Ghent University, Belgium

An Algebraic Structure for Moufang Quadrangles

Description

Very recently, the classification of Moufang polygons has been completed by Tits and Weiss. Moufang n-gons exist for n in { 3, 4, 6, 8 } only. For n in { 3, 6, 8 }, the proof is nicely divided into two parts: first, it is shown that a Moufang n-gon can be parametrized by a certain interesting algebraic structure, and secondly, these algebraic structures are classified. The classification of Moufang quadrangles (n=4) is not organized in this way due to the absence of a suitable algebraic structure. The goal of this article is to present such a uniform algebraic structure for Moufang quadrangles, and to classify these structures without referring back to the original Moufang quadrangles from which they arise, thereby also providing a new proof for the classification of Moufang quadrangles, which does consist of the division into these two parts. We hope that these algebraic structures will prove to be interesting in their own right.

Contents

Introduction
Definition
Some identities
From quadrangular systems to Moufang quadrangles
From Moufang quadrangles to quadrangular systems
Some remarks
Examples
The classification
Appendix A. Abelian quadrangular systems
Bibliography

Details:

Series: Memoirs of the American Mathematical Society, Volume: 818
Publication Year: 2005
ISBN: 0-8218-3608-0
Paging: 99 pp.
Binding: Softcover

Vadim A. Kaimanovich, Universite Rennes, France, and Mikhail Lyubich, SUNY at Stony Brook, NY

Conformal and Harmonic Measures on Laminations Associated with Rational Maps

Description

The framework of affine and hyperbolic laminations provides a unifying foundation for many aspects of conformal dynamics and hyperbolic geometry. The central objects of this approach are an affine Riemann surface lamination mathcal A and the associated hyperbolic 3-lamination mathcal H endowed with an action of a discrete group of isomorphisms. This action is properly discontinuous on mathcal H, which allows one to pass to the quotient hyperbolic lamination mathcal M. Our work explores natural "geometric" measures on these laminations.

We begin with a brief self-contained introduction to the measure theory on laminations by discussing the relationship between leafwise, transverse and global measures. The central themes of our study are: leafwise and transverse "conformal streams" on an affine lamination mathcal A (analogues of the Patterson-Sullivan conformal measures for Kleinian groups), harmonic and invariant measures on the corresponding hyperbolic lamination mathcal H, the "Anosov--Sinai cocycle", the corresponding "basic cohomology class" on mathcal A (which provides an obstruction to flatness), and the Busemann cocycle on mathcal H. A number of related geometric objects on laminations -- in particular, the backward and forward Poincare series and the associated critical exponents, the curvature forms and the Euler class, currents and transverse invariant measures, lambda-harmonic functions and the leafwise Brownian motion -- are discussed along the lines.

The main examples are provided by the laminations arising from the Kleinian and the rational dynamics. In the former case, mathcal M is a sublamination of the unit tangent bundle of a hyperbolic 3-manifold, its transversals can be identified with the limit set of the Kleinian group, and we show how the classical theory of Patterson-Sullivan measures can be recast in terms of our general approach. In the latter case, the laminations were recently constructed by Lyubich and Minsky in [LM97]. Assuming that they are locally compact, we construct a transverse delta-conformal stream on mathcal A and the corresponding lambda-harmonic measure on mathcal M, where lambda=delta(delta-2). We prove that the exponent delta of the stream does not exceed 2 and that the affine laminations are never flat except for several explicit special cases (rational functions with parabolic Thurston orbifold).

Contents

Introduction
Affine and hyperbolic laminations
Measures and currents on laminations
Laminations associated with rational maps
Measures on laminations associated with rational maps
Appendix A. Laminations associated with Kleinian groups
List of notations
Bibliography

Details:

Series: Memoirs of the American Mathematical Society,Volume: 820
Publication Year: 2005
ISBN: 0-8218-3615-3
Paging: 119 pp.
Binding: Softcover

Edited by: Bernhelm Boos-Bavnbek, Roskilde University, Denmark, Gerd Grubb, University of Copenhagen, Denmark, and Krzysztof P. Wojciechowski, Indiana University-Purdue University, Indianapolis, IN

Spectral Geometry of Manifolds with Boundary and Decomposition of Manifolds

Description

In recent years, increasingly complex methods have been brought into play in the treatment of geometric and topological problems for partial differential operators on manifolds. This collection of papers, resulting from a Workshop on Spectral Geometry of Manifolds with Boundary and Decomposition of Manifolds, provides a broad picture of these methods with new results.

Subjects in the book cover a wide variety of topics, from recent advances in index theory and the more general theory of spectral invariants on closed manifolds and manifolds with boundary, to applications of those invariants in geometry, topology, and physics.

Papers are grouped into four parts: Part I gives an overview of the subject from various points of view. Part II deals with spectral invariants, such as traces, indices, and determinants. Part III is concerned with general geometric and topological questions. Part IV deals specifically with problems on manifolds with singularities. The book is suitable for graduate students and researchers interested in spectral problems in geometry.

Contents

Part I. Basic material-Reviews
D. V. Vassilevich -- Spectral problems from quantum field theory
G. Esposito -- Euclidean quantum gravity in light of spectral geometry
G. Grubb -- Analysis of invariants associated with spectral boundary problems for elliptic operators
Part II. Spectral invariants and asymptotic expansions
G. Grubb -- A resolvent approach to traces and zeta Laurent expansions
Y. Lee -- Asymptotic expansion of the zeta-determinant of an invertible Laplacian on a stretched manifold
J. Park and K. P. Wojciechowski -- Agranovich-Dynin formula for the zeta-determinants of the Neumann and Dirichlet problems
Part III. Geometric and topological problems
H. U. Boden, C. M. Herald, and P. Kirk -- The Calderon projector for the odd signature operator and spectral flow calculations in 3-dimensional topology
E. Leichtnam and P. Piazza -- Cut-and-paste on foliated bundles
M. Lesch -- The uniqueness of the spectral flow on spaces of unbounded self-adjoint Fredholm operators
M. Marcolli and B.-L. Wang -- Variants of equivariant Seiberg-Witten Floer homology
Part IV. Manifolds with singularities
P. Loya -- Dirac operators, boundary value problems, and the b-calculus
V. E. Nazaikinskii, G. Rozenblum, A. Yu. Savin, and B. Yu. Sternin -- Guillemin transform and Toeplitz representations for operators on singular manifolds
V. Nistor -- Pseudodifferential operators on non-compact manifolds and analysis on polyhedral domains

Details:

Series: Contemporary Mathematics, Volume: 366
Publication Year: 2005
ISBN: 0-8218-3536-X
Paging: 328 pp.
Binding: Softcover