# Gen 1.0 - Gen 2.0 VMs and Staking

Blockchain rollups are scaling solutions that move expensive computation off-chain to Layer-2 (L2) chains. Validity roll-ups use succinct arguments of knowledge (SNARKs) to compute proofs and relocate expensive computations to L2. Consequently, the network participants only need to verify succinct proofs at Layer-1 (L1) attesting to the correctness of the off-chain computation. This approach allows verifying the L2 state, resulting from several batched transactions, as part of one transaction verified on the main chain. Validity roll-ups reduce the transaction fees for the end users, as the gas cost to run the verifier and batch transactions at L2 is significantly lower compared to the gas cost required to execute them naively at L1.

While validity roll-ups pose a remarkably viable solution to scale a decentralised network like Ethereum, it is severely bottlenecked by the proving overheads for non-algebraic computations such as Keccak hashes. It is estimated that, at present, the overhead to compute proofs for such non-algebraic hashes is at least 20,000 times higher. Most computations in real-world applications are non-algebraic, and converting them into algebraic operations inside a proof system brings considerable additional overheads. Consequently, the throughput rate of most current validity roll-ups is far less than what was initially expected.

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