Plasma cash and all the coin splitting mechanisms can be generalized into Sharded Plasma.
Idea is somehow similar to tree of Plasma chains but offers izolation of deposits like Plasma Cash and it might be possible to combine those two.
Sharded Plasma consists of Root Plasma blockchain, smart contract on Ethereum and Plasma Shards.
- Root Plasma blocks has merkle tree mapping shardId \rightarrow shardDataHash
- Ethereum Smart Contract maintains shardId \rightarrow deposits. Every deposit and withdrawal is constrained to a shard. There can be additional rules enforced like for Cash there can be only one deposit per shard.
- Plasma Shards for each block are empty or hold some data. In case of Plasma Cash data is a signle transaction. If each shard is like an “Original Plasma” it would be a merkle tree of transactions.
Only thing sharding adds to withdrawal process is specifying shardId and providing proof inclusion of each referenced shard data in Root Plasma.
Like in Cash user only needs to keep track of history of shards it has a stake in.
This way basically any Plasma design can be sharded as long as there is no need of inter shard communication. Also shards can be heterogeneus, for example person making first deposit to a shard could choose if it’s a single coin, can it be split or should it have Original Plasma in it.