An introduction to the theory of functional equations and inequalities: Cauchy's equation and Jensen's inequality (2nd ed.)

Part 1 of this book lists the required knowledge in set and measure theory, topology and algebra.

Part 2 gives details on solutions of the Cauchy equation and of the Jensen inequality while part 3 deals with related equations and inequalities before the text concludes with an excursion into the field of extensions of homomorphisms.