Theoretical foundations
In this section, various theoretical concepts will be introduced that have been developed with the introduction of different altcoins in the past few years.
Alternatives to Proof of Work
The PoW scheme in the context of cryptocurrency was first used in Bitcoin and served as a mechanism to provide assurance that a miner had completed the required amount of work to find a block. This process, in turn, provided decentralization, security, and stability for the blockchain. This is the primary vehicle in Bitcoin for providing decentralized distributed consensus. PoW schemes are required to have a much-desired property called progress freeness, which means that the reward for consuming computational resources should be random and proportional to the contribution made by the miners. In this case, some chance of winning the block reward is given to even those miners who have comparatively less computational power.
The term progress freeness was introduced...