Dumb question - 

If a rollup switches out DA to some low cost DA solution, is there a major difference in cost savings if it’s ZK vs Optimistic? What’s the best way to think about the differences there?

The first modular blockchain network that makes it easy for anyone to securely launch their own blockchain. Build whatever 👉 https://celestia.org/build/

A robust base layer designed to meet the needs of next-generation trust-minimized applications and sovereign rollups

availproject.org

cc: @eigenda @celestia @availproject @near

Scientist by day, other things at night.

Writing complex and nuanced takes, viewed by few, appreciated by none.

Do you have a sense for how big the difference is?

Optimistic rollups need more storage, because they need to publish enough information for anyone to replay the transactions. Validity rollups only need to publish the state differences, and a short proof that transition followed the rules. It's a tradeoff of compute and storage. Thus saving is larger for optimistic.

Yep, how do the cost improvements tend to differ between the two

Hey Rhett! Do you mean if it makes a difference if the rollup’s construct is ZK or optimistic?

assuming a "honest" centralized sequencer + decentralized fraud proof system (i.e. anyone can submit fraud proofs) over the long run, optimiums will be cheaper, simply because they do not submit zk-proofs for finality (which can have variable/fixed gas costs) but rely on the "challenge period" for finality