3.2 Let (Yn) be a square integrable (Fn)n-martingale. 3.2.1 State the Jensen's inequality. 3.2.2 Show that (Y2) is an (Fn)n-submartingale.

3.2 Let (Yn) be a square integrable (Fn)n-martingale. 3.2.1 State the Jensen's inequality. 3.2.2 Show that (Yn2) is an (Fn)n-submartingale. 3.2 Let (Yn) be a square integrable (Fn)n-martingale. 3.2.1 State the Jensen's inequality. 3.2.2 Show that (Yn2) is an (Fn)n-submartingale