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IxDRL: A Novel Explainable Deep Reinforcement Learning Toolkit Based on Analyses of Interestingness

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Explainable Artificial Intelligence (xAI 2023)

Abstract

In recent years, advances in deep learning have resulted in a plethora of successes in the use of reinforcement learning (RL) to solve complex sequential decision tasks with high-dimensional inputs. However, existing systems lack the necessary mechanisms to provide humans with a holistic view of their competence, presenting an impediment to their adoption, particularly in critical applications where the decisions an agent makes can have significant consequences. Yet, existing RL-based systems are essentially competency-unaware in that they lack the necessary interpretation mechanisms to allow human operators to have an insightful, holistic view of their competency. Towards more explainable Deep RL (xDRL), we propose a new framework based on analyses of interestingness. Our tool provides various measures of RL agent competence stemming from interestingness analysis and is applicable to a wide range of RL algorithms, natively supporting the popular RLLib toolkit. We showcase the use of our framework by applying the proposed pipeline in a set of scenarios of varying complexity. We empirically assess the capability of the approach in identifying agent behavior patterns and competency-controlling conditions, and the task elements mostly responsible for an agent’s competence, based on global and local analyses of interestingness. Overall, we show that our framework can provide agent designers with insights about RL agent competence, both their capabilities and limitations, enabling more informed decisions about interventions, additional training, and other interactions in collaborative human-machine settings.

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Notes

  1. 1.

    The IxDRL toolkit code is available at: https://github.com/SRI-AIC/ixdrl.

  2. 2.

    Without loss of generality, here we deal with episodic tasks.

  3. 3.

    This corresponds to using the backward finite difference coefficient with accuracy 2 [10]. A higher-order accuracy could be used if we wish to capture how the value function is changing for the computation of Goal Conduciveness, by using information from timesteps further back in the trace.

  4. 4.

    This quantity is also known as the one-step TD or TD(0) target.

  5. 5.

    Our framework also computes stochasticity from models parameterizing continuous distributions, using an appropriate coefficient of variation in place of Leik’s D.

  6. 6.

    Our implementation also computes familiarity from an ensemble of predictive models parameterizing distributions instead of outputting point predictions, in which case we use divergence measures between prediction distributions to replace for d.

  7. 7.

    All configurations used to train the RL agents, as well the data for each scenario, are available at: https://github.com/SRI-AIC/23-xai-ixdrl-data.

  8. 8.

    https://gymnasium.farama.org/environments/atari/breakout/.

  9. 9.

    https://gymnasium.farama.org/environments/mujoco/hopper/.

  10. 10.

    We used the implementation at: https://github.com/JannerM/mbpo.

  11. 11.

    A more detailed description of our SC2 task is provided in [40].

  12. 12.

    For traces with similar length, alternative methods such as Dynamic Time Warping (DTW) [37] could be used to align and compute the distances between traces.

  13. 13.

    Because these dimensions rely on information from multiple timesteps, a more robust model, making use of past information, is likely required to provide good predictions.

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Acknowledgements

This material is based upon work supported by the Defense Advanced Research Projects Agency (DARPA) under Contract No. HR001119C0112. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the DARPA.

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Sequeira, P., Gervasio, M. (2023). IxDRL: A Novel Explainable Deep Reinforcement Learning Toolkit Based on Analyses of Interestingness. In: Longo, L. (eds) Explainable Artificial Intelligence. xAI 2023. Communications in Computer and Information Science, vol 1901. Springer, Cham. https://doi.org/10.1007/978-3-031-44064-9_20

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