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计算机工程 ›› 2022, Vol. 48 ›› Issue (12): 112-118. doi: 10.19678/j.issn.1000-3428.0063365

• 人工智能与模式识别 • 上一篇    下一篇

一种半监督对抗鲁棒模型无关元学习方法

胡彬1, 王晓军2, 张雷2   

  1. 1. 南京邮电大学 计算机学院, 南京 210023;
    2. 南京邮电大学 物联网学院, 南京 210023
  • 收稿日期:2021-11-26 修回日期:2022-02-17 发布日期:2022-02-21
  • 作者简介:胡彬(1997—),男,硕士研究生,主研方向为数据挖掘、机器学习;王晓军(通信作者),副研究员;张雷,讲师。
  • 基金资助:
    国家自然科学基金(61971235)。

A Semi-Supervised Adversarial Robust Model-Agnostic Meta-Learning Method

HU Bin1, WANG Xiaojun2, ZHANG Lei2   

  1. 1. School of Computer Science, Nanjing University of Posts and Telecommunications, Nanjing 210023, China;
    2. School of Internet of Things, Nanjing University of Posts and Telecommunications, Nanjing 210023, China
  • Received:2021-11-26 Revised:2022-02-17 Published:2022-02-21

摘要: 元学习期望训练所得的元模型在学习到的“元知识”基础上利用来自新任务的少量标注样本,仅通过较少的梯度下降步骤微调模型就能够快速适应该任务。但是,由于缺乏训练样本,元学习算法在元训练期间对现有任务过度训练时所得的分类器决策边界不够准确,不合理的决策边界使得元模型更容易受到微小对抗扰动的影响,导致元模型在新任务上的鲁棒性能降低。提出一种半监督对抗鲁棒模型无关元学习(semi-ARMAML)方法,在目标函数中分别引入半监督的对抗鲁棒正则项和基于信息熵的任务无偏正则项,以此优化决策边界,其中对抗鲁棒正则项的计算允许未标注样本包含未见过类样本,从而使得元模型能更好地适应真实应用场景,降低对输入扰动的敏感性,提高对抗鲁棒性。实验结果表明,相比ADML、R-MAML-TRADES等当下主流的对抗元学习方法,semi-ARMAML方法在干净样本上准确率较高,在MiniImageNet数据集的5-way 1-shot与5-way 5-shot任务上对抗鲁棒性能分别约提升1.8%和2.7%,在CIFAR-FS数据集上分别约提升5.2%和8.1%。

关键词: 少样本学习, 元学习, 对抗训练, 半监督学习, 对抗鲁棒性

Abstract: The meta model developed by meta learning is expected to have the ability of "learning to learn". Therefore, it can quickly adapt to new tasks based on the learned "meta knowledge", with a small number of gradient descent steps to fine-tune the model using a few labeled training data from new tasks.However, owing to the scarcity of training sampling data, when the meta-learning algorithm overtrains the existing tasks during the meta-training phase, the decision boundary trained by the meta learner is not sufficiently accurate.The unreasonable decision boundary makes the meta model more vulnerable to adversarial perturbation, which may lead to poor robustness performance of the meta model on new tasks.Therefore, a semi-supervised Adversarial Robust Model-Agnostic Meta-Learning(semi-ARMAML) method is proposed.A semi-supervised adversarial robust regularizer and a task-agnostic regularizer based on information entropy are integrated into the objective function to optimize the decision boundary.In particular, the calculation of the adversarial robust regularizer allows the unlabeled dataset to contain the classes unseen in the labeled dataset.The developed meta model performs better on new tasks of real application scenes and is more robust on input disturbances.The experimental results indicate that the scheme has a higher accuracy rate on clean samples.Compared with current mainstream adversarial meta-learning schemes such as ADML and R-MAML-TRADES, the adversarial robustness performance of the semi-ARMAML method improved by approximately 1.8% and 2.7% on the five-way one-shot and five-way five-shot tasks of the MiniImageNet dataset, respectively, and by approximately 5.2% and 8.1% on the five-way one-shot and five-way five-shot tasks of the CIFAR-FS dataset, respectively.

Key words: Few-Shot Learning(FSL), meta-learning, adversarial training, semi-supervised learning, adversarial robustness

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