In order to fully unlock the transformative power of distributed ledgers and blockchains, it is crucial to develop innovative consensus algorithms that can overcome the obstacles of security, scalability, and interoperability, which currently hinder their widespread adoption. This paper introduces HybridChain that combines the advantages of sharded blockchain and DAG distributed ledger, and a consensus algorithm that leverages decentralized learning. Our approach involves validators exchanging perceptions as votes to assess potential conflicts between transactions and the witness set, representing input transactions in the UTXO model. These perceptions collectively contribute to an intermediate belief regarding the validity of transactions. By integrating their beliefs with those of other validators, localized decisions are made to determine validity. Ultimately, a final consensus is achieved through a majority vote, ensuring precise and efficient validation of transactions. Our proposed approach is compared to the existing DAG-based scheme IOTA and the sharded blockchain Omniledger through extensive simulations. The results show that IOTA has high throughput and low latency but sacrifices accuracy and is vulnerable to orphanage attacks especially with low transaction rates. Omniledger achieves stable accuracy by increasing shards but has increased latency. In contrast, the proposed HybridChain exhibits fast, accurate, and secure transaction processing, and excellent scalability.

翻译：摘要：为充分释放分布式账本与区块链的变革潜力，亟需设计创新性共识算法以克服当前制约其大规模应用的安全性、可扩展性及互操作性障碍。本文提出HybridChain——一种融合分片区块链与有向无环图（DAG）分布式账本优势的架构，并创新性地引入基于去中心化学习的共识算法。该算法中，验证节点通过交换感知投票来评估交易与见证集（即UTXO模型中的输入交易表征）之间的潜在冲突，这些感知共同构建关于交易有效性的中间置信度。验证节点通过整合自身与其他节点的置信度，实施局部化决策以判定交易有效性，最终通过多数投票达成全局共识，实现交易验证的精准高效。通过大规模仿真实验，我们将本方案与现有DAG架构IOTA及分片区块链Omniledger进行对比。结果表明：IOTA虽具备高吞吐量与低延迟特性，但牺牲了验证准确性，且在低交易率场景下易受孤儿攻击；Omniledger通过增加分片数量维持稳定准确性，却导致延迟升高。而本文提出的HybridChain在保持交易处理快速性、准确性与安全性的同时，展现出卓越的可扩展性。