The Ghost in Ethereum (Greedy Heaviest Observed Subtree) was introduced in 2013 as a way to combat the fact that blocking blocks with fast block time suffer from a large number of obsolete blocks – that is, blocks that were distributed on the network and tested by some nodes. They are certainly correct, but eventually discarded, like a longer chain. The protocol also struggles with the problem of centralization offset – the larger the pool, the less time is spent, the more often they gain an advantage over other blocks, producing the block itself and immediately launching the program to create the next block.
An obsolete block is created when two nodes find the block simultaneously. Then both nodes report that they have found a solution for this block and sent their block to check and plug it into other block circuits. In Bitcoin, the probability of finding a block is relatively low, since the blocking time is ten minutes, and the distribution of the block to 50% of the network takes about twelve seconds.
If you want the lock time to be shorter, and also want to reduce the speed for combining the production, as Ethereum does – then you need to do this with GHOST.
GHOST includes obsolete blocks – or Uncles, as Ethereum calls them – they are included in the calculation, which of the chains is long or has the highest cumulative complexity. Centralization is decided by granting block rewards 87.5%, and nephew (ancestor of the Uncles block) also receives a reward of 12.5% of the block.
In the version of Ethereum, Ghost only goes down seven levels or raises the chain of blocks to seven levels.
- The block must indicate its ancestors and the number of Uncles.
- Uncles included in the block must be a direct descendant of the new block, and also a descendant of blocks that are seven blocks below it in height
- It can not be a direct ancestor of the formed block.
- Uncles must have a valid block header.
- Uncles should be different from all other Uncles-type units and be formed according to a new one.
- For each Uncles included in the block, the miner receives an additional 3.125%, and the Uncles miner gets 93.75% of the standard block award.