Active Approximately Metric-Fair Learning

Yiting Cao, Chao Lan

Abstract: Existing studies on individual fairness focus on the passive setting and typically require $O(\frac{1}{\varepsilon^2})$ labeled instances to achieve an $\varepsilon$ bias budget. In this paper, we build on the elegant Approximately Metric-Fair (AMF) learning framework and propose an active AMF learner that can provably achieve the same budget with only $O(\log \frac{1}{\varepsilon})$ labeled instances. To our knowledge, this is a first and substantial improvement of the existing sample complexity for achieving individual fairness. Through experiments on three data sets, we show the proposed active AMF learner improves fairness on linear and non-linear models more efficiently than its passive counterpart as well as state-of-the-art active learners, while maintaining a comparable accuracy. To facilitate algorithm design and analysis, we also design a provably equivalent form of the approximate metric fairness based on uniform continuity instead of the existing almost Lipschitz continuity.