In this paper, we describe the global structure of webs in codimension one, and study in particular their singularities (the caustic). We define and study different concepts which have no interest locally near regular points, such as the type, the reducibility, the quasi-smoothness, the CIproperty (complete intersection), the dicriticity.... As an example of application, we explain how the alge...

We present a simple method to deal with caustics in the semiclassical approximation to the thermal density matrix of a particle moving on the line. For simplicity, only its diagonal elements are considered. The only ingredient we require is the knowledge of the extrema of the Euclidean action. The procedure makes use of complex trajectories, and is applied to the quartic double-well potential.

We present a simple method to deal with caustics in the semiclassical approximation to the partition function of a one-dimensional quantum system. The procedure, which makes use of complex trajectories, is applied to the quartic double-well potential.