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Remembering Transformer: A Continual Learning Approach Inspired by Complementary Learning Systems

Core Concepts
Remembering Transformer employs a mixture-of-adapters and a generative model-based routing mechanism to alleviate catastrophic forgetting in continual learning by dynamically routing task data to relevant adapters.
The paper proposes a novel Remembering Transformer architecture for continual learning, inspired by the Complementary Learning Systems (CLS) in the brain. The key aspects are: Mixture-of-Adapters in Vision Transformers: The method leverages a mixture of low-rank adapter modules that are sparsely activated with a generative model-based novelty detection mechanism. This allows efficient fine-tuning of a pre-trained Vision Transformer (ViT) for different tasks without interfering with previously learned knowledge. Generative Model-based Novelty Detection and Expert Routing: A collection of generative models (autoencoders) are used to assess the familiarity of the current task with respect to previously learned tasks. The autoencoder with the minimum reconstruction loss on the input is used to select the most relevant adapter for processing the data, without requiring task identity information. Adapter Fusion based on Knowledge Distillation: When the maximum number of adapters is limited, the method aggregates similar adapters through knowledge distillation, transferring knowledge from a selected old adapter to the new one. This improves parameter efficiency while retaining performance. The extensive experiments on class-incremental learning tasks demonstrate the superior performance and parameter efficiency of the Remembering Transformer compared to a wide range of existing continual learning methods.
The CIFAR-10 dataset is divided into 5 tasks, and the CIFAR-100 dataset is divided into 10 and 20 tasks. The Remembering Transformer achieves an average accuracy of 88.43% across the different tasks, outperforming the second-best method by 15.90%. With a limited adapter capacity (E=3), the Remembering Transformer achieves 93.2% accuracy on the CIFAR-10/5 task, while having a much smaller memory footprint (0.22M) compared to other methods.
"Remembering Transformer employs a mixture-of-adapters and a generative model-based routing mechanism to alleviate Catastrophic Forgetting (CF) by dynamically routing task data to relevant adapters." "The empirical results, including an ablation study, demonstrate the superiority of Remembering Transformer compared to a broad spectrum of existing methods, in terms of parameter efficiency and model performance in various vision continual learning tasks."

Key Insights Distilled From

by Yuwei Sun,Ju... at 04-12-2024
Remembering Transformer for Continual Learning

Deeper Inquiries

How can the Remembering Transformer architecture be extended to other domains beyond computer vision, such as natural language processing or speech recognition?

The Remembering Transformer architecture's core principles, such as the mixture-of-adapters and generative model-based routing, can be extended to domains beyond computer vision, like natural language processing (NLP) or speech recognition. In NLP tasks, the Transformer model can be adapted to handle sequential data by tokenizing text inputs and applying the same adapter routing mechanism. For instance, in a language translation task, different adapters can be specialized for translating specific language pairs, with the generative model detecting the relevance of each adapter based on the input text's characteristics. Similarly, in speech recognition, the Remembering Transformer can utilize adapters specialized for different accents or languages, with the generative model guiding the routing of audio inputs to the most relevant adapter based on acoustic features.

What are the potential limitations or drawbacks of the generative model-based novelty detection approach, and how could it be further improved?

One potential limitation of the generative model-based novelty detection approach is the computational complexity involved in training and maintaining multiple generative models for different tasks. Training these models on large datasets can be resource-intensive and time-consuming. Additionally, the performance of the novelty detection mechanism heavily relies on the quality of the generative models and the representation power of the features they learn. If the generative models fail to capture the task distributions accurately, it may lead to incorrect routing decisions and impact the overall performance of the Remembering Transformer. To address these limitations and improve the generative model-based novelty detection approach, several strategies can be considered. Firstly, incorporating techniques like transfer learning or pre-training the generative models on diverse datasets can enhance their ability to capture task-specific distributions effectively. Secondly, exploring more efficient architectures, such as lightweight neural networks or attention mechanisms, can reduce the computational burden of training and inference. Additionally, leveraging techniques like ensemble learning or model distillation can improve the robustness and generalization of the generative models, making them more reliable for novelty detection in continual learning scenarios.

Could the Remembering Transformer be combined with other continual learning techniques, such as meta-learning or task-agnostic approaches, to further enhance its performance and flexibility?

Yes, the Remembering Transformer can benefit from synergies with other continual learning techniques like meta-learning or task-agnostic approaches to enhance its performance and flexibility. By integrating meta-learning strategies, the Remembering Transformer can adapt more quickly to new tasks by leveraging meta-learned priors or initialization schemes. Meta-learning can help the model generalize better across tasks and improve sample efficiency during adaptation. Furthermore, incorporating task-agnostic approaches, such as parameter regularization or dynamic architecture adjustments, can enhance the Remembering Transformer's flexibility in handling diverse tasks. Task-agnostic methods can help mitigate catastrophic forgetting by preserving important task-specific information while adapting to new tasks. Additionally, techniques like lifelong learning constraints or continual learning benchmarks can provide a structured framework for evaluating and improving the Remembering Transformer's continual learning capabilities across various domains. By combining the Remembering Transformer with complementary continual learning techniques, researchers can create a more robust and adaptive model that excels in handling a wide range of sequential learning tasks while maintaining efficiency and performance.