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Disentangling the Causes of Plasticity Loss in Neural Networks

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arxiv 2402.18762 v1 pith:RGNXWHTE submitted 2024-02-29 cs.LG

Disentangling the Causes of Plasticity Loss in Neural Networks

classification cs.LG
keywords learningplasticitylossmechanismsnetworkalgorithmsassumptionhighly
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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Underpinning the past decades of work on the design, initialization, and optimization of neural networks is a seemingly innocuous assumption: that the network is trained on a \textit{stationary} data distribution. In settings where this assumption is violated, e.g.\ deep reinforcement learning, learning algorithms become unstable and brittle with respect to hyperparameters and even random seeds. One factor driving this instability is the loss of plasticity, meaning that updating the network's predictions in response to new information becomes more difficult as training progresses. While many recent works provide analyses and partial solutions to this phenomenon, a fundamental question remains unanswered: to what extent do known mechanisms of plasticity loss overlap, and how can mitigation strategies be combined to best maintain the trainability of a network? This paper addresses these questions, showing that loss of plasticity can be decomposed into multiple independent mechanisms and that, while intervening on any single mechanism is insufficient to avoid the loss of plasticity in all cases, intervening on multiple mechanisms in conjunction results in highly robust learning algorithms. We show that a combination of layer normalization and weight decay is highly effective at maintaining plasticity in a variety of synthetic nonstationary learning tasks, and further demonstrate its effectiveness on naturally arising nonstationarities, including reinforcement learning in the Arcade Learning Environment.

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Cited by 15 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

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  4. Beyond One-Size-Fits-All: Diagnosis-Driven Online Reinforcement Learning with Offline Priors

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  5. Preserving Plasticity in Continual Learning via Dynamical Isometry

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  13. Activation Function Design Sustains Plasticity in Continual Learning

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  15. Plasticity Loss in Deep Reinforcement Learning: A Survey

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