Baer function

The Baer function is a mathematical concept that arises in the context of real analysis and function theory. Specifically, it is a type of function that has certain properties related to measurability and can be used to exemplify various concepts in measure theory. The Baer function is constructed to be a function from the real numbers to the real numbers that is not Lebesgue measurable, which serves to illustrate the existence of non-measurable sets.