In information theory, there is something called the maximum entropy principle. Are other information measures, such as mutual information, also commonly maximized? If mutual information describes the reduction in uncertainty of characterizing one random variable (r.v. 1) based on full knowledge of a second random variable (r.v. 2), then would maximizing mutual information mean knowing everything about r.v. 2 will allow us to also have full knowledge of r.v. 1?