The Ethereum yellow paper available at https://ethereum.github.io/yellowpaper/paper.pdf has been written by Dr. Gavin Wood, Founder, Ethereum & Parity (http://gavwood.com) and serves as a formal definition of the Ethereum protocol. Anyone can implement an Ethereum client by following the protocol specifications defined in the paper.
While this paper can be somewhat challenging to read, especially for those who do not have a background in algebra or mathematics and are not familiar with mathematical notations, it contains a complete formal specification of Ethereum. This specification can be used to implement a fully compliant Ethereum client.
The list of all symbols with their meanings used in the paper is provided here with ...
