始终激活的聚类间排斥机制会损害持续学习效果,需改进为有阈值的触发式策略。
Failure Modes of Always-On Inter-Cluster Repulsion in Replay-Based Continual Learning
- 在重放学习中加入持续作用的聚类间排斥,试图提升特征分离度。
- 实验显示该方法最高仅达22.5%准确率,且遗忘高达89.2个百分点。
- 问题根源是排斥项不饱和、持续拉扯,适合改用条件触发式设计。
基于特征空间的目标常被引入重放式持续学习系统,期望通过更好的几何分离提升记忆保持能力。本文研究一种初步的聚类感知重放(CAR)形式,结合类别均衡的重放缓存与始终激活的聚类间排斥项(ICF)。在五任务分割CIFAR-10上使用ResNet-18主干网络,六组敏感性测试中最高平均最终准确率为22.5±1.4%(三组随机种子),低于仅使用重放的23.1±2.5%。无重放时的ICF仅达19.2±0.1%。所有测试排斥权重下的最终准确率均介于20.1%至22.5%之间,详细配置下平均遗忘达89.2±1.5个百分点。仪器化重运行显示,当交叉熵接近零后,加权排斥贡献仍维持在约-0.13,导致总目标函数为负,旧任务准确率崩溃。重要的是,归一化距离目标在数学上是受约束的,因此失败本质并非无界损失,而是非饱和、始终激活的排斥。这些负面结果表明,几何分离并非自动与重放互补,提示应采用梯度在足够分离后自动关闭的边际门控目标。
原文摘要 · Abstract (English)
Feature-space objectives are often added to replay-based continual learning systems with the expectation that better geometric separation will improve retention. We study a preliminary form of Cluster-Aware Replay (CAR) that combines a class-balanced replay memory with an always-active inter-cluster repulsion term (ICF). On five-task Split CIFAR-10 with a ResNet-18 backbone, the highest observed mean in a six-value sensitivity sweep reaches $22.5\pm1.4\%$ final average accuracy over three seeds, compared with $23.1\pm2.5\%$ for replay alone. ICF without replay reaches only $19.2\pm0.1\%$. All tested repulsion weights produce final accuracies between $20.1\%$ and $22.5\%$, and the detailed configuration exhibits $89.2\pm1.5$ percentage points of average forgetting. An instrumented rerun shows that the weighted repulsion contribution remains near $-0.13$ after cross-entropy has fallen close to zero, so the total objective becomes negative while old-task accuracy collapses. Importantly, the normalized distance objective is mathematically bounded; the failure is therefore better described as non-saturating, always-on repulsion rather than an unbounded loss. These negative results show that geometric separation is not automatically complementary to replay and motivate margin-gated objectives whose gradients deactivate once sufficient separation has been reached.
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