Updates
@vbuterin has posted an excellent summary of trust-minimized side chains with on-chain data availabiliy (which the community has generally settled to calling “rollups”). Described are two flavors: one using validity proofs (known as zk-rollups) and another using fraud proofs, extending his earlier “shadow chains.” Unlike shadow chains, rollup avoid persisting state transitions on-chain in state.
This post on Minimal Viable Merged Consensus can be compared to @barryWhiteHat’s [zk] roll_up using fraud proofs instead of validity proofs. Rollups using fraud proofs have been extended from Buterin’s work by former Plasma Group (@karl, @benj0702, and Jinglan Wang) in the context of their Optimistic Virtual Machine (OVM) language, and bear the more descriptive name “optimistic rollups.”