Plasma Debit (see https://ethresear.ch/t/plasma-debit-arbitrary-denomination-payments-in-plasma-cash/2198) explicitly calls itself a Plasma flavor, and is arguably much closer to an account-based model than a UTXO-based one; in fact, it seems to have very similar properties to what this is proposing. So I do think the way the Plasma community has been using the term Plasma lately is closer to the expansive definition than the restrictive one.

Examples of things that I think everyone would agree are definitely not Plasma include:

• Bitcoin-style “Proof of Existence” — because Plasma inherently hinges on using Merkle trees with committed roots to provide proof of non-existence of double-spends (both to users and to a parent chain)
• Layer-1 blockchains (including sharded systems with “tight coupling”)
• “Sidechains” that are not “trustless” in the sense of the word commonly used in this context
• Merkle trees as used in Truebit, or proofs of custody, or proofs of independent execution, or any other such protocol.
• Proofs of non-existence for many kinds of non-financial applications. For example, suppose that an issuing authority publishes a sparse Merkle tree of public keys that is a blacklist of identities that it considers no longer value, and I provide a branch of the Merkle tree that shows that there is no value in the tree at the index that would correspond to my public key.

I do agree the community should try to aim for a clearer definition though.

Source and More information: Plasma Debit (see…

Author: Vitalik Buterin