Principle of maximum caliber

The principle of maximum caliber (MaxCal) or maximum path entropy principle, suggested by E. T. Jaynes, can be considered as a generalization of the principle of maximum entropy. It postulates that the most unbiased probability distribution of paths is the one that maximizes their Shannon entropy. This entropy of paths is sometimes called the "caliber" of the system, and is given by the path integral

${\displaystyle S[\rho [x()]]=\int D_{x}\,\,\rho [x()]\,\ln {\rho [x()] \over \pi [x()]}}$