Georgia Institute of Technology College of Sciences

In Watchareepan Atiponrat's thesis the properties of decomposable exact Lagrangian codordisms betweenLegendrian links in R^3 with the standard contact structure were studied. In particular, for any decomposableexact Lagrangian filling L of a Legendrian link K, one may obtain a normal ruling of K associated with L.Atiponrat's main result is that the associated normal rulings must have an even number of clasps. As a result, there exists a Legendrian (4,-(2n +5))-torus knot, for each n >= 0, which does not have a decomposable exact Lagrangian filling because it has only 1 normal ruling and this normal rolling has odd number of clasps.