Reinforcement Learning with Mutual Information Regularized Policies to Protect Sensitive State Variables

핵심 개념

The core message of this paper is to develop a reinforcement learning framework that learns policies that maximize reward while minimizing the disclosure of sensitive state variables through the agent's actions.

초록

The paper introduces a reinforcement learning (RL) framework that learns policies that maximize reward while minimizing the disclosure of sensitive state variables through the agent's actions. The key ideas are: Formulate the problem as a constrained optimization problem, where the objective is to maximize reward while constraining the mutual information between the agent's actions and the sensitive state variables. Develop several gradient estimators to efficiently optimize this constrained objective, including a model-based estimator, a model-free upper bound estimator, and a reparameterization-based estimator for differentiable environments. Demonstrate the effectiveness of the approach on a variety of tasks, including a tabular web connection problem, a 2D continuous control task, and high-dimensional simulated robotics tasks. The learned policies are able to effectively hide the sensitive state variables while maintaining high reward. Compare the approach to differentially private RL and a previous mutual information regularization method, showing the advantages of the proposed mutual information constraint formulation. The key insight is that by directly optimizing the mutual information between actions and sensitive state, the agent can learn policies that intelligently plan ahead to reduce information disclosure, going beyond simply adding noise. This allows achieving high reward while satisfying strong privacy guarantees.

통계

The paper does not contain any explicit numerical data or statistics to support the key claims. The results are presented qualitatively through visualizations of the learned policies and their behavior.

인용구

"We formulate this privacy-constrained RL problem as an optimization problem with an additional regularizer on the mutual information between a function of the action at and a function of the protected state ut at each timestep t, induced under the learned policy q." "Optimizing this regularizer is not straightforward since it is distribution-dependent (unlike the reward), and involves marginalization over the non-sensitive state." "Experiments show that our constrained optimization finds the optimal privacy-constrained policy in an illustrative tabular environment and hides sensitive state in a continuous control problem. Finally, we show that the reparameterized estimator can find policies which effectively hide the sensitive state in high-dimensional (simulated) robotics tasks."

핵심 통찰 요약

Privacy-Constrained Policies via Mutual Information Regularized Policy Gradients

by Chris Cundy,... 게시일 arxiv.org 04-17-2024

https://arxiv.org/pdf/2012.15019.pdf

더 깊은 질문

How can the proposed approach be extended to settings with multiple sensitive state variables, or where the sensitive variables change over time

The proposed approach can be extended to settings with multiple sensitive state variables or where the sensitive variables change over time by modifying the mutual information constraint to account for these complexities. Multiple Sensitive State Variables: In cases where there are multiple sensitive state variables, the mutual information constraint can be extended to consider the joint mutual information between the actions and all sensitive variables. This would involve calculating the mutual information between the actions and the entire set of sensitive variables at each timestep. By optimizing the policy to minimize this joint mutual information, the policy can be trained to hide information about all sensitive variables simultaneously. Changing Sensitive Variables: When the sensitive variables change over time, the mutual information constraint can be adapted to account for this dynamic nature. The constraint can be formulated to minimize the mutual information between the actions and the current sensitive state variable, given the history of sensitive variables up to that point. This would involve incorporating a time-dependent component into the mutual information constraint, ensuring that the policy adapts to changes in the sensitive information over time. By incorporating these modifications into the mutual information regularization framework, the approach can effectively handle settings with multiple sensitive state variables and dynamic changes in the sensitive information.

What are the theoretical guarantees on the privacy-utility tradeoff achieved by the mutual information constrained policies, and how do they compare to differential privacy approaches

Theoretical guarantees on the privacy-utility tradeoff achieved by the mutual information constrained policies can be analyzed in comparison to differential privacy approaches: Privacy Guarantees: The mutual information constrained policies aim to minimize the information leakage between the actions and the sensitive state variables. The theoretical guarantee is that the mutual information between these variables is reduced to a specified level, as constrained by the optimization objective. This ensures that the policy limits the disclosure of sensitive information through its actions. Utility Tradeoff: The tradeoff between privacy and utility is inherent in the mutual information constrained policies. By optimizing the policy to minimize mutual information while maximizing reward, there is a balance struck between protecting sensitive information and achieving the desired task performance. The theoretical guarantees would involve analyzing how this tradeoff is managed and ensuring that the policy achieves a satisfactory level of utility while maintaining privacy. Comparison to Differential Privacy: Differential privacy approaches provide a different perspective on privacy guarantees, focusing on the impact of individual data points on the overall privacy of the dataset. In contrast, mutual information constraints in reinforcement learning target the information leakage between actions and sensitive variables. The comparison would involve evaluating the robustness of mutual information constraints in preserving privacy compared to the formal guarantees of differential privacy. By examining the theoretical foundations of mutual information constrained policies and comparing them to differential privacy approaches, a comprehensive understanding of the privacy-utility tradeoff can be obtained.

Can the ideas in this paper be applied to other machine learning settings beyond reinforcement learning, such as supervised learning or generative modeling, to learn models that protect sensitive information

The ideas presented in this paper can be applied to other machine learning settings beyond reinforcement learning, such as supervised learning or generative modeling, to learn models that protect sensitive information: Supervised Learning: In supervised learning tasks, mutual information constraints can be incorporated to ensure that the predictions made by the model do not reveal sensitive information present in the input data. By regularizing the mutual information between the model's outputs and the sensitive variables, the model can be trained to make predictions while preserving privacy. Generative Modeling: In generative modeling, mutual information constraints can be used to control the information flow between the generated samples and the sensitive variables. By minimizing the mutual information between the generated samples and the sensitive information, generative models can be trained to generate data that does not disclose sensitive details. Privacy-Preserving Machine Learning: The principles of minimizing mutual information to protect sensitive information can be applied across various machine learning domains to enhance privacy preservation. By adapting the mutual information regularization framework to different settings, models can be developed that prioritize privacy while maintaining performance. By extending the concepts of mutual information constraints to supervised learning and generative modeling tasks, the approach can be leveraged to create privacy-preserving models in a broader range of machine learning applications.