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房智轩

上海期智研究院PI(2020年7月-至今)
清华大学助理教授

个人简介

上海期智研究院PI,清华大学交叉信息研究院助理教授。

博士毕业于清华大学交叉信息研究院,本科毕业于北京大学物理学院,在加入清华大学之前,曾在香港中文大学任博士后研究员。目前研究兴趣专注于互联网共享与交易平台的分析与优化、区块链系统的机制设计、网络经济学、群体智能等。

研究方向

区块链系统:高性能、激励相容的区块链系统设计与分析

多智能体博弈学习:多智能体协作、博弈、学习、决策的基础理论

去中心化计算:去中心化网络系统中的高效可信计算

亮点成果

成果2:基于弱区块信号的有向无环图区块链交易选择协议

       基于有向无环图(DAG)的区块链允许多个区块并发地添加到系统中,从而提高区块链系统的吞吐性能。但现实中并发的区块中可能会包含相同的交易,而这些冗余的交易碰撞会降低系统的利用率,甚至可能还会严重影响系统性能。

       基于DAG的区块链由于高并发和网络延迟而面临交易碰撞的关键挑战,房智轩团队提出了“We-TIPS”,一种基于弱区块的交易包含协议,利用弱区块头的信息传递来解决这一关键挑战。在We-TIPS中,矿工可以在挖矿过程中将其弱区块头作为信号提前进行广播,该信号可以指示矿工当前的交易包含情况。通过信号的及时广播,矿工可以有效避免交易选择碰撞,提升吞吐性能。此外,作者在We-TIPS协议中研究了矿工之间的交易选择博弈,并证明该博弈本质就是一个势博弈(Potential Game),并进一步设计了一种可以实现近似纳什均衡的去中心化算法。该方法在实验中最高实现了98%的区块利用率,大幅领先现有方案。

       该成果获得了无线网络优化领域顶会WiOpt 2023的最佳论文提名奖(Best paper candidate)。

2023房智轩成果照片2.png

       该成果研究论文:

       Canhui Chen and Zhixuan Fang, “We-TIPS: Weak-Block-Based Transaction Inclusion Protocol with Signaling in DAG-based Blockchain,” Proceedings of the 21th International Symposium on Modeling and Optimization in Mobile, Ad hoc, and Wireless Networks (WiOpt), August 2023. (Best Paper Candidate)  查看PDF


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成果1:拍卖视角下的区块链挖矿机制分析

       抽卡销售(Gacha Game)是一种特殊的销售方式。与传统的直接出售商品不同,卖方向买方出售抽奖的机会。买方的每次抽取将以一个预设的(可变)概率胜出,从而获得该商品。抽卡销售广泛应用于各类销售中,如彩票和游戏中虚拟商品的销售。

       针对这种复杂的销售模式,房智轩团队首次研究提出了严密的数学建模框架,将买方的顺序决策建模为马尔可夫决策过程(MDP),并给出了抽卡销售种卖家收益最大化策略的必要条件。此外,作者展示了抽卡销售与单一物品、单一买家拍卖(single-item single-bidder auction)的等价性,从而导出能够实现最大卖方收益的最优参数。此外,该工作的结果还证实当玩家有预算约束时,抽卡销售可以比拍卖带来更高的卖方收益。

       与此同时,房智轩团队解释了抽卡销售模型与区块链挖矿过程的对应关系。其中,卖家对应区块链系统,而买家则对应矿工。区块链系统(卖家)希望最大化系统的安全性(即“销售利润”),而增强系统安全性的方法就是增加买家(矿工)的哈希尝试次数或者资产抵押数量(即卖家的抽取次数)。这种对应关系指出了区块链系统安全性与用户投入的内生关系,从而给出了进一步利用成熟的拍卖理论来指导区块链最优设计的可能。

       该成果发表在计算机性能建模与分析的顶级会议ACM SIGMETRICS 2023上。

2023房智轩成果照片1.png

       该研究成果论文:Canhui Chen and Zhixuan Fang,“Gacha Game Analysis and Design,” in Proceedings of the ACM on Measurement and Analysis of Computing Systems (POMACS), 2023. [Accepted directly through ACM SIGMETRICS 2023] 查看PDF

团队成员

论文发表

22. Canhui Chen, Zhixuan Fang, We-TIPS: Weak-Block-Based Transaction Inclusion Protocol with Signaling in DAG-based Blockchain, WiOpt, 2023 查看PDF


21. Rongwu Xu, Sen Yang, Fan Zhang, Zhixuan Fang, MISO: Legacy-compatible Privacy-preserving Single Sign-on using Trusted Execution Environments, Euro S&P, 2023 查看PDF


20. Canhui Chen, Zerui Cheng, Shutong Qu, Zhixuan Fang, Crowdsourcing Work as Mining: A Decentralized Computation and Storage Paradigm, APNET, 2023 查看PDF


19. Canhui Chen, Zhixuan Fang, Gacha Game Analysis and Design, ACM SIGMETRICS, 2023 查看PDF


18. Yunshu Liu, Zhixuan Fang, Man Hon Cheung, Wei Cai, Jianwei Huang, Mechanisms Design for Blockchain Storage Sustainability, IEEE Communications Magazine, 2023 查看PDF


17. Qingsong Liu, Zhixuan Fang, Learning to Schedule Tasks with Deadline and Throughput Constraints, INFOCOM, 2023 查看PDF


16. Canhui Chen, Xu Chen, and Zhixuan Fang†, TIPS: Transaction Inclusion Protocol with Signaling in DAG-Based Blockchain, (JSAC) IEEE Journal on Selected Areas in Communications , 2023 查看PDF


15. Yunshu Liu, Shulin Ke, Zhixuan Fang, Man Hon Cheung, Wei Cai, and Jianwei Huang, A Storage Sustainability Mechanism with Heterogeneous Miners in Blockchain, (JSAC) IEEE Journal on Selected Areas in Communications, 2022 查看PDF


14. Yunshu Liu, Zhixuan Fang, Man Hon Cheung, Wei Cai, and Jianwei Huang, An Incentive Mechanism for Sustainable Blockchain Storage, (ToN) IEEE/ACM Transactions on Networking, 2022 查看PDF


13. Qingsong Liu, Weihang Xu, Siwei Wang, and Zhixuan Fang†, Combinatorial Bandits with Linear Constraints: Beyond Knapsacks and Fairness, (NeurIPS) Proceedings of the Thirty-sixth Conference on Neural Information Processing Systems, 2022 查看PDF 


12. Yirui Zhang, Siwei Wang, and Zhixuan Fang†, Matching in Multi-arm Bandit with Collision, (NeurIPS) Proceedings of the Thirty-sixth Conference on Neural Information Processing Systems, 2022 查看PDF 


11. Jiayuan Liu, Canhui Chen, Lulu Zhou, and Zhixuan Fang†, Real-Time Recursive Routing in Payment Channel Network: A Bidding-based Design, (WiOpt) Proceedings of the 20th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, 2022 查看PDF 


10. Qingsong Liu, Zhuoran Li, and Zhixuan Fang†, Online Convex Optimization with Switching Costs: Algorithms and Performance, (WiOpt) Proceedings of the 20th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, 2022 查看PDF 


9. Hongbo Zhang, Sizheng Fan, Zhixuan Fang, and Wei Cai, Economic Analysis of Decentralized Exchange Market with Transaction Fee Mining, (BSCI) In 2022 ACM International Symposium on Blockchain and Secure Critical Infrastructure, 2022 查看PDF


8. Jingfan Yu, Mengqian Zhang, Xi Chen, Zhixuan Fang†, SoK: Play-to-Earn Projects, arxiv, 2022 查看PDF


7. Qingsong Liu, Wenfei Wu, Longbo Huang, Zhixuan Fang†, Simultaneously Achieving Sublinear Regret and Constraint Violations for Online Convex Optimization with Time-varying Constraints, (Performance) ACM SIGMETRICS Performance Evaluation Review (IFIP Performance '21 conference), 2022 查看PDF


6. Qingsong Liu, Wenfei Wu, Longbo Huang, Zhixuan Fang†, Simultaneously Achieving Sublinear Regret and Constraint Violations for Online Convex Optimization with Time-varying Constraints, (PEVA) Performance Evaluation, 2021 查看PDF


5. Ningning Ding; Zhixuan Fang; Lingjie Duan; Jianwei Huang, Optimal Incentive and Load Design for Distributed Coded Machine Learning, (JSAC) IEEE Journal on Selected Areas in Communications, 2021 查看PDF


4. Ningning Ding; Zhixuan Fang; Jianwei Huang, Optimal Contract Design for Efficient Federated Learning With Multi-Dimensional Private Information, (JSAC) IEEE Journal on Selected Areas in Communications, 2021 查看PDF


3. Yihan Du, Siwei Wang, Zhixuan Fang, and Longbo Huang,  Continuous Mean-Covariance Bandits, (NeurIPS) Proceedings of the 35th Conference on Neural Information Processing Systems, 2021 查看PDF 


2. Ningning Ding; Zhixuan Fang; Lingjie Duan; Jianwei Huang, Incentive Mechanism Design for Distributed Coded Machine Learning, (INFOCOM) Proceedings of IEEE International Conference on Computer Communications, 2021 查看PDF


1. Ningning Ding, Zhixuan Fang, and Jianwei Huang, Information Disclosure Game on Sharing Platforms, (Globecom) Proceedings of The 2020 IEEE Global Communications Conference, 2021 查看PDF