Aurélien Bellet

Date: Wednesday, 25th October 2017 at 2pm
Place: LORIA, room C005
Speaker: Aurélien Bellet (Inria Lille – Nord Europe)

Title: Private algorithms for decentralized collaborative machine learning

Abstract: With the advent of connected devices with computation and storage capabilities, it becomes possible to run machine learning on-device to provide personalized services. However, the currently dominant approach is to centralize data from all users on an external server for batch processing, sometimes without explicit consent from users and with little oversight. This centralization poses important privacy issues in applications involving sensitive data such as speech, medical records or geolocation logs.

In this talk, I will discuss an alternative setting where many agents with local datasets collaborate to learn models by engaging in a fully decentralized peer-to-peer network. We introduce and analyze asynchronous algorithms in the gossip and broadcast communication model that allow agents to improve upon their locally trained model by exchanging information with other agents that have similar objectives. Our first approach aims to smooth pre-trained local models over the network while accounting for the confidence that each agent has in its initial model. In our second approach, agents jointly learn and propagate their model by making iterative updates based on both their local dataset and the behavior of their neighbors. I will also describe how to make such algorithms differentially private to avoid leaking information about the local datasets, and analyze the resulting privacy-utility trade-off.