You Don't Know The Math Michael Maiello, 09.29.09, 06:00 AM EDT The complexities of the financial markets are beyond your broker's abilities. Four years retired from Yale, Benoit Mandelbrot, the inventor of fractal geometry, is still trying to teach the essential lesson of his life's work--nature and markets defy easy description. Anyone who tells you otherwise is either trying to sell you something, doesn't know the math or both. Last week, Mandelbrot, 84, spoke to a gathering of diplomats, business leaders and philanthropists at the Louise Blouin Foundation's Creative Leadership Summit. Mandelbrot has also served as mentor to economist Nassim...