Towards Return Parity in Markov Decision Processes
- URL: http://arxiv.org/abs/2111.10476v1
- Date: Fri, 19 Nov 2021 23:25:38 GMT
- Title: Towards Return Parity in Markov Decision Processes
- Abstract summary: We study a fairness problem in Markov decision processes (MDPs)
We propose return parity, a fairness notion that requires MDPs from different demographic groups to achieve the same expected rewards.
Motivated by our decomposition theorem, we propose algorithms to mitigate return disparity via learning a shared group policy with state visitation distributional alignment.
- Score: 36.96748490812215
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Algorithmic decisions made by machine learning models in high-stakes domains
may have lasting impacts over time. Unfortunately, naive applications of
standard fairness criterion in static settings over temporal domains may lead
to delayed and adverse effects. To understand the dynamics of performance
disparity, we study a fairness problem in Markov decision processes (MDPs).
Specifically, we propose return parity, a fairness notion that requires MDPs
from different demographic groups that share the same state and action spaces
to achieve approximately the same expected time-discounted rewards. We first
provide a decomposition theorem for return disparity, which decomposes the
return disparity of any two MDPs into the distance between group-wise reward
functions, the discrepancy of group policies, and the discrepancy between state
visitation distributions induced by the group policies. Motivated by our
decomposition theorem, we propose algorithms to mitigate return disparity via
learning a shared group policy with state visitation distributional alignment
using integral probability metrics. We conduct experiments to corroborate our
results, showing that the proposed algorithm can successfully close the
disparity gap while maintaining the performance of policies on two real-world
recommender system benchmark datasets.
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