Kac's formula, vertices of chains and equidecomposability of functions and enhanced functions (PHD thesis)

This PHD thesis hinges on the terms mentioned in the title. It introduces a formalism which allows one to find equalities generalizing the formula of Mark Kac which deals with a measure-preserving transformation. The formalism is meaningful for general measure-preserving actions of groups ("discrete", "continuous", "multidimensional"). Some aspects of the notions introduced are investigated.