OSDTW: Optimal Shared Depth and Task Weighting for Long-Tailed Recognition
- URL: http://arxiv.org/abs/2605.24969v1
- Date: Sun, 24 May 2026 09:48:02 GMT
- Title: OSDTW: Optimal Shared Depth and Task Weighting for Long-Tailed Recognition
- Abstract summary: Long-tailed recognition suffers from a persistent head--tail trade-off.<n>We propose a principled task-decomposition framework that partitions the original single-label recognition problem into a head task and a tail task.<n>We show that the resulting Kullback-Leibler divergence-based generalization error can be written as the sum of task-wise terms up to an additive constant.
- Score: 12.869661291857843
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: Long-tailed recognition suffers from a persistent head--tail trade-off: improving tail performance often degrades head accuracy and can increase training instability. Despite strong empirical results from re-weighting, decoupled training, and multi-expert methods, key design choices about representation sharing between head and tail classes and supervision weighting across class groups remain largely heuristic. In this work, we propose OSDTW, a principled task-decomposition framework that partitions the original single-label recognition problem into a head task and a tail task, implemented with a shared encoder and task-specific decoders. To handle the mutual exclusivity and statistical dependence between the two label groups, we introduce a factorized model and show that the resulting Kullback--Leibler divergence-based generalization error can be written as the sum of task-wise terms up to an additive constant, yielding a well-defined task-wise objective. We further develop a three-stage training pipeline: independent task training to estimate task-wise optima and the Fisher information matrix, weighted joint training to learn a shared encoder, and branch assembly to construct the final decoupled model. Under a block-diagonal Fisher approximation, we derive a computable second-order expansion of the expected generalization error, decomposing it into encoder variance, encoder bias, and decoder variance. This bias--variance decomposition provides a computable proxy to select the shared depth and task weights, enabling efficient hyper-parameter search. Experiments on standard long-tailed benchmarks demonstrate the effectiveness of the proposed approach over strong baselines.
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