1 (Couplings and monotonicity). A coupling of two or more random variables is nothing but a simultaneous reconstruction of (copies of) the variables in the same probability model. For example, let X and Y are Bernoulli random variables each taking values 0 and 1 with probability 1/2. We can construct a coupling (X̃, Ỹ ) of X and Y by generating a uniform random variable Z over the set {00, 01, 1...