论文标题

强大的几次学习,无需使用任何对抗样本

Robust Few-shot Learning Without Using any Adversarial Samples

论文作者

Nayak, Gaurav Kumar, Rawal, Ruchit, Khatri, Inder, Chakraborty, Anirban

论文摘要

获取和注释样本的高昂成本使“几乎没有”学习问题的重要性。现有作品主要集中于改善对清洁数据的性能,并忽略对对抗性噪声扰动的数据的鲁棒性问题。最近,已经采取了一些努力,将几个问题与使用复杂的元学习技术相结合的稳健目标。这些方法依赖于培训的每一集中的对抗样本的产生,这进一步增加了计算负担。为了避免这种耗时且复杂的程序,我们提出了一种简单但有效的替代方案,不需要任何对抗性样本。受到人类认知决策过程的启发,我们通过自我蒸馏在预段阶段中实施了基类数据及其相应的低频样本之间的高级特征。然后,在新型类别的样本上进行了微调,我们还通过余弦相似性提高了低频查询集特征的可区分性。在CIFAR-FS数据集的1次设置中,我们的方法在PGD和最新的汽车攻击上分别获得了60.55美元的$ 60.55 \%$&$ 62.05 \%$的对抗性准确性,与基线相比,清洁准确性略有下降。此外,我们的方法仅占标准培训时间的$ 1.69 \ times $,而$ \ $ \ $ 5 \ $ 5 \ times $ $ $ $ $ $ $ $ $。该代码可在https://github.com/vcl-iisc/robust-few-shot-learning上找到。

The high cost of acquiring and annotating samples has made the `few-shot' learning problem of prime importance. Existing works mainly focus on improving performance on clean data and overlook robustness concerns on the data perturbed with adversarial noise. Recently, a few efforts have been made to combine the few-shot problem with the robustness objective using sophisticated Meta-Learning techniques. These methods rely on the generation of adversarial samples in every episode of training, which further adds a computational burden. To avoid such time-consuming and complicated procedures, we propose a simple but effective alternative that does not require any adversarial samples. Inspired by the cognitive decision-making process in humans, we enforce high-level feature matching between the base class data and their corresponding low-frequency samples in the pretraining stage via self distillation. The model is then fine-tuned on the samples of novel classes where we additionally improve the discriminability of low-frequency query set features via cosine similarity. On a 1-shot setting of the CIFAR-FS dataset, our method yields a massive improvement of $60.55\%$ & $62.05\%$ in adversarial accuracy on the PGD and state-of-the-art Auto Attack, respectively, with a minor drop in clean accuracy compared to the baseline. Moreover, our method only takes $1.69\times$ of the standard training time while being $\approx$ $5\times$ faster than state-of-the-art adversarial meta-learning methods. The code is available at https://github.com/vcl-iisc/robust-few-shot-learning.

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