I watched the heated discussion about "layer3" in overseas communities and found it particularly interesting: some people saw the inter-chain matryoshka dolls where data is repeatedly compressed, some saw the atomic communication capabilities of ZK as the underlying technology architecture between multi-chain applications, and some saw the Then we saw the wider application scenarios of Eigenlayer’s AVS staking + reward and punishment mechanism. How to understand the extended meaning of layer3? Let me explain my understanding: 1) Since layer2 and layer3 theoretically rely on mainnet settlement, a common assumption is that layer3 first compresses the data and then submits it to layer2 for secondary compression, which is equivalent to Rollup. Applying Rollup again, this method has been criticized and questioned, because once we imagine layer4 and layer5 with a similar architecture, this method will be squeezed into a dead end. After all, the data cannot be compressed all the time. 2) In fact, the interaction between layer3 and layer2 may not necessarily require compression and then compression. In the layer3 strategy planned by many layer2 Stacks such as Arbitrum and zkSync, layer3 is defined as a specific application chain and will be highly autonomous in terms of consensus mechanism, Gas Fee selection, economic model, etc. The problem is that autonomy does not mean complete Independent, its underlying architecture will most likely be constrained by using the basic infra built by layer2, for example, sharing key components such as Sequencer and Prover with the layer2 chain. This means that layer3 transactions will be directly packaged and submitted to the mainnet via layer2's Sequencer for final status confirmation. What layer2 undertakes more is the interoperability Function between layer3 multi-chains. The so-called "settlement layer" is only the settlement of data packaging, not the final and final settlement in the true sense. Transactions in layer 3 also need to be queued and packaged on layer 2. Make Sense is achieved by treating the layer 3 application chain as a special Sequencer pipeline. 3) If we assume that layer3 is all in the form of inter-chain nesting dolls, the scalability will naturally be limited. However, this practical approach is only a theoretical assumption. If layer2 and layer3 share key components such as Sequencer and Prover, there are many ways to make layer3 more Chain horizontal expansion, especially after the interoperability between chains is improved. 1. As zkSync founder @gluk64 said, based on ZK technology as the basis for interoperability between multiple chains, ZK technology allows two Counterparties to verify the authenticity of information without revealing specific information. When layer3 When moving cross-chain assets to layer 2, the atomic transfer of assets between chains can be achieved through ZK Bridge Street without the need to superimpose inter-chain consensus or other processing.The bridge technology supported by ZK technology can provide a foundation for the multi-chain expansion of layer3, because no matter how many layer3s appear, they are directly "technical settlement" with layer2 through ZK Proof, and will not affect the relationship between layer2 and the main network;   2. As explained by @sreeramkannan, the founder of Eigenlayer, allowing Eigenlayer's AVS active nodes to cross-chain coordinate the consensus between different multi-chains is equivalent to allowing the same batch of nodes to participate in consensus construction between multiple chains. In this way, as long as AVS is given a layer of reward and punishment Slash mechanism, the possibility of nodes doing evil by themselves will be reduced in theory. When a node approves the flow of assets from layer3 to layer2, if there is any evil behavior, it will be Slashed.   This kind of reward and punishment economic mechanism will also be applied to the trust problem in a multi-chain environment. Although it cannot be 100% trustworthy like ZK, it can roughly create a trusted environment built on an economic model. 4) @VitalikButerin also jumped out to reiterate his own point of view in response to the discussion of everyone's own positions. Layer3 cannot be simply a stacking and extension of layer2, which cannot bring effective scalability. Because layer3 relies on layer2 as infrastructure, layer2 cannot achieve endless expansion, let alone layer3. But in some specific scenarios, such as privacy, layer3 specific privacy application chains can solve the privacy preference of some transactions. In short, layer3 is a highly customized function and has the possibility of customized expansion. In my opinion, the expansion of layer3 should be customized according to the needs of application scenarios. The development paradigm of one-click chain launch will not work in the direction of multi-chain application of layer3.

#Layer2