This rigorous textbook tames technicalities and makes even the most complex models accessible to students. Its unique two-tier structure makes the book attractive for undergraduates, graduates and researchers alike. In fact, the coverage is primarily directed to undergraduate students and is mainly confined to graphic analysis and to some elementary algebra. Further, each chapter has its own mathematical appendix, in which (i) the topics treated in the text are examined at a level suitable for advanced undergraduates, graduates and researchers, and (ii) generalizations and/or topics not...