Dual of the Janus geometry

We discuss the aspect of the Janus geometries and their dual gauge theories. We first review the Janus geometry/ICFT correspondence. We also review the dual gauge theory description of the cosmological solution by the procedure of the double Wick rotation. The coupling is driven either to zero or to infinity at the big-bang and big-crunch singularities, which are shown to be related by the S-duality symmetry, In the dual Yang-Mills theory description, these are non singular at all as the coupling goes to zero in the N = 4 Super Yang-Mills theory.