Source: Dongkun Hou et. al., "A Systematic Literature Review of Blockchain-Based Federated Learning: Architectures, Applications and Issues" in 2nd Info. Comm. Tech. Conf. pp. 302-307 (May 2021)
The Thesis.
"Federated learning (FL) can realize a distributed training machine learning models in multiple deices while protecting their data privacy, but some defect still exists such as single point failure and lack of motivation. Blockchain as a distributed ledger can be utilized to provide a novel FL framework to address those issues." (Id. at 302)
The Key Points.
4 Problems with Current Federated Learning Approaches (which Blockchain Architectures Can Address):
- Single point of failure
- Poison attack
- Lack of motivation (lack of voluntary data contribution)
- Privacy leakage
The Details.

