Title : Contact geometry in low dimensions Abstract: This series of talks will be about explaining some fundamental open problems in three-dimensional contact geometry. This third talk will be on overtwisted vs. tight dichotomy (or flexible vs. rigid), and existence problem of tight contact structures.  

Title: Lie Groupoid Abstract: Motivation and introduction to the general theory of groupoid, Lie groupoid and Lie algebroid. Few examples are given, in particular the gauge groupoid.  

Title: Atiyah sequence Abstract: Review of the theory of exact sequences to define a connection on a principal bundle. The construction of a gauge theory of gravity on a Lie algebroid is considered.