The Status of Volatility Modeling

I'd like to know from you about the joint calibration of S&P and Vakes as Miles, which is something you have worked on for some time. Martin Gleie: It's true that it's an important and intriguing problem. I think I contributed to revive quite a lot the subject by obtaining the first what I call exact calibration. And this was done an interesting model which is non-parametric.