Federated Unlearning and Server Right to Forget: Handling Unreliable Client Contributions

In the context of federated learning, the concept of federated unlearning has emerged, aiming to realize the "right to be forgotten". The current research primarily focuses on designing unlearning techniques for clients "right to be forgotten", it has often bypassed to consider the server's authority to discard the client contribution without taking any consent from participating clients, we named it "right to forget". These client contributions may contain adverse effects that could significantly impact global aggregation. In this research paper, we conduct a comprehensive review of previous studies related to federated unlearning and explore the server "right to forget" client's contributions. We also introduce new taxonomies to classify and summarize the latest advancements in federated unlearning algorithms. Moreover, we take the first step to present the server right to forget (SRF), a novel unlearning methodology that enables the server to remove unreliable client contributions to improve global model accuracy. Experiments on two different kinds of datasets and models demonstrate the effectiveness of our method. We envision our effort as a first step toward the server's right to forget the client's contribution in the context of federated unlearning toward adherence to legal and ethical standards in a just and transparent manner.