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These notes originate from a seminar held in Pisa in November and December 1996 jointly by Riccardo Benedetti, Paolo Lisca and me. The aim of these notes is to give a detailed proof of the following result due to Eliashberg and Thurston: THM Let M be a closed oriented 3-manifold and let F be a cooriented C2-smooth codimension-1 foliation on M. Assume that (M, F) is not diffeomorphic to the product foliation on S2xS1. Then arbitrarily close to F in the C0 topology there exist a positive and a negative C\infty contact structure

During the past 20 years spectral curves have proved to be a successful geometrical tool for studying a large number of Hamiltonian systems. In 1987 Hitchin applied the theory of spectral curves, considering the moduli space of stable principal G-bundles over a compact Riemann surface C and used spectral curves to describe the cotangent bundle T*M as an "algebraically completely integrable Hamiltonian system", defining an analytic map H: T*M->K, where K is a suitable vector space. In this work we provide an explicit description of the generic fibres of H in term of both generalized Prym varieties and Prym-Tjurin varieties in the Jacobian of suitable spectral curves.

These are transcripts of notes taken at (some of) the lectures given at the Mittag-Leffler Institute during the first semester of the year 1996/97 on Enumerative geometry and its interaction with theoretical physics. The first part of this collection consists of notes from talks on the basics of quantum cohomology; the second part treats more advanced topics in quantum cohomology; the third part consists of background material and related topics; an appendix gives a description of Kresch's C-program Farsta for quantum cohomology computations. These notes are meant as a series of snapshots of quantum cohomology as seen by the speakers at the time of their lectures. The reader should bear in mind that quantum cohomology is a growing and rapidly changing field. Many of the writeups have been left in the form of the original talks, which were usually more concerned with giving motivations and a point of view, rather than conveying detailed proofs or attempting to survey the considerably extensive literature on the subject.

At the end of October 1985 a group of friends gathered at the Scuola Normale Superiore, Pisa, to celebrate Gian Carlo Wick's seventy-fifth birthday. They came from near and far to talk physics with him as they had been doing for so many years. And they talked about theory and experiments as they knew that Gian Carlo had always thought that these two sides of physics should never be separated. We dedicate the papers that were presented at the meeting to a dear friend from whose wisdom and knowledge we all profited.

The notes are based on lectures on stochastic processes given at Scuola Normale Superiore in 1999 and 2000. Some new material was added and only selected, less standard results were presented. We did not include several applications to statistical mechanics and mathematical finance, covered in the lectures, as we hope to write part two of the notes devoted to applications of stochastic processes in modelling. The main themes of the notes are constructions of stochastic processes. We present different approaches to the existence question proposed by Kolmogorov, Wiener, Ito and Prohorov. Special attention is also paid to Levy processes. The lectures are basically self-contained and rely only on elementary measure theory and functional analysis. They might be used for more advanced courses on stochastic processes.

This volume collects two articles by Christine Laurent-Thiébaut and Jürgen Leiterer which were submitted to, and accepted by the Annali della Scuola Normale Superiore, Classe di Scienze: The q-convex case; the q-concave case. Owing to the character of the systematic exposition of the new scientific results achieved and to the size of the work, the authors agreed to have the two papers published in a separate volume.