About this document.

This eventually should be merged into the ``Distributed Consensus'' section of A Treatise on Altcoins, but as that is very unfinished, in the meantime the author is releasing it as a standalone article.

Because of the interaction between incentive analysis and cryptography, this subject makes for frequent and mentally-taxing discussions on IRC. The goal of this document is to clarify the fundamentals and put these discussions on sounder footing.