In this book Christian Prem features new innovations on several levels. On a conceptual level he presents a complete restructuring and modularisation of the field of lending theory. On a formal level he bestows great care on providing precise definitions and promotes notational standardisation. On a technical level the development of an algorithm to solve repayment games automatically is thoroughly documented. Eventually, new theoretic results on the performance of various credit schemes are established, the quality of existing lending schemes is scrutinised and new more efficient mechanisms are presented. The content therefore inspires theorists as well as it provides well-grounded advice to practitioners in the lending industry. Altogether this thesis is a major step towards improving the quality and applicability of lending theory.