KENNEDY'S TALK: The tangent star cone TS(X) of a scheme X is the normal cone of the diagonal in X-times-X; similarly one can define the relative tangent star cone TS(X/T) of a morphism from X to T. Geometrically, TS(X) consists of limiting secant lines to X, as the two points approach each other. But TS(X) may also have a surprisingly intricate scheme structure. Being cones, TS(X) and TS(X/T) carry Segre classes. Now suppose that the Segre class s(TS(X/T)) specializes, over a point t of T, to s(TS(Xt)), the Segre class of the fiber. Then, in certain circumstances, one can show that TS(X/T) is flat over T above t.

SUWA'S TALK: Some of the important formulas in Complex Analytic Geometry or Algebraic Geometry can be naturally interpreted as ``residue formulas", which are obtained by localizing certain characteristic classes of vector bundles or coherent sheaves.
This sort of theory fits nicely into the framework of the Cech-deRham cohomology. In fact, it provides not only a simple and natural way to prove the classical formulas but also means to deal with a wider range of problems such as the ones on singular varieties or singular foliations. The method is also effective for problems related to characteristic classes in other areas including Symplectic Geometry. I will try to explain the underlying basic ideas and the essentials of some of the following recent developements : 1) theory of Milnor classes for singular varieties, 2) multiplicity of functions on singular varieties, 3) Riemann-Roch theorem for embeddings of singular varieties and its applications, 4) simple proof of the Lefschetz fixed point formula, 5) residues of singular foliations and its application to complex dynamical systems and 6) localization of Maslov classes.

BRASSELET'S TALK: The Euler-Poincar'e characteristic is the first example of a characteristic class. It can be defined by various ways, mainly topological and geometrical ones. From the Euler-Poincar'e characteristic and through Poincar'e-Hopf theorem, we will pass to obstruction theory. Various examples will be given to show the geometric point of view of the theory.