f′ = f o f deals with the non-linear differential equation in which the derivative f′ is required to equal the self-composition f o f. The right-hand side uses the solution f to determine the non-linear structure of the problem solved. So, in a sense, the answer is required to define the problem. This work was begun with Professor Igor Skrypnik. The published version is in the East-West Journal of Mathematics in 2001. Computations and constructions in the paper (as easily downloaded and executed) MAPLE programs. Copies of the paper are available.

ABC Entropy is an introduction to Shannon entropies and their use in measuring information/patterns. Preprint.