\[ \newcommand{\or}{\textrm{ or }} \newcommand{\and}{\textrm{ and }} \newcommand{\not}{\textrm{not }} \newcommand{\Pois}{\textrm{Poisson}} \newcommand{\E}{\textrm{E}} \newcommand{\var}{\textrm{Var}} \]
\[ \newcommand{\or}{\textrm{ or }} \newcommand{\and}{\textrm{ and }} \newcommand{\not}{\textrm{not }} \newcommand{\Pois}{\textrm{Poisson}} \newcommand{\E}{\textrm{E}} \newcommand{\var}{\textrm{Var}} \]