  Proof-of-Work (PoW) is a popular consensus protocol used by Bitcoin since its
inception. PoW has the well-known flaw of assigning all the reward to the
single miner (or pool) that inserts the new block. This has the consequence of
making the variance of the reward and thus the mining enterprise risk extremely
high. To address this problem, Shi in 2016 proposed a theoretical algorithm
that would substantially reduce the issue. We introduce a variant of
Proof-of-Work that improves on Shi's idea and can be easily implemented in
practice. In order to insert a block, the network must not find a single nonce,
but must find a few of them. This small change allows for a fairer distribution
of rewards and at the same time has the effect of regularizing the insertion
time of blocks. This would facilitate the emergence of small pools or
autonomous miners.
