The “Why”s of Optimistic Rollup

What Is Optimistic Rollup?

Not this one. (Source)

I’ll Do You One Better: Why Is Optimistic Rollup?

If a greedy attacker is able to assemble more CPU power than all the honest nodes, he would have to choose between using it to defraud people by stealing back his payments, or using it to generate new coins. He ought to find it more profitable to play by the rules, such rules that favour him with more new coins than everyone else combined, than to undermine the system and the validity of his own wealth.

Now, the idea is to create an entire “shadow chain”, with computations happening off-chain but state transitions being committed back to the main chain after 100 blocks. Oracles can add new blocks to the “tail” of the chain, where a block consists of a list of transactions and a [[k1, v1], [k2, v2] ... ] list of state transitions caused by those transactions. If a block is unchallenged for 100 blocks, the state transitions are applied automatically to the main chain.

Optimistic rollup gives you instant, gas-free transactions!

Teams Building Optimistic Rollup

Conclusions

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