filter banks and they allow us to define new kinds of complexity measures in particular this Hessian measure that we talked about it's all in there and say there's some some papers that people would like to take a peek and I'd be happy to answer any additional questions [Applause] it's all really a question the second derivative of that one so yeah so the basically the the way the way that we think about it is that you have a it's okay there's there's let's stop it to hear a heuristic way of thinking about it is if you had a piecewise-defined