IMPROVING THE GENERALIZATION OF ADVERSARIAL TRAINING WITH DOMAIN ADAPTATION
By injecting adversarial examples into training data, adversarial training is promising for improving the robustness of deep learning models. However, most existing adversarial training approaches are based on a specific type of adversarial attack. It may not provide sufficiently representative samples from the adversarial domain, leading to a weak generalization ability on adversarial examples from other attacks. Moreover, during the adversarial training, adversarial perturbations on inputs are usually crafted by fast single-step adversaries so as to scale to large datasets. This work is mainly focused on the adversarial training yet efficient FGSM adversary. In this scenario, it is difficult to train a model with great generalization due to the lack of representative adversarial samples, aka the samples are unable to accurately reflect the adversarial domain. To alleviate this problem, we propose a novel Adversarial Training with Domain Adaptation (ATDA) method. Our intuition is to regard the adversarial training on FGSM adversary as a domain adaption task with limited number of target domain samples. The main idea is to learn a representation that is semantically meaningful and domain invariant on the clean domain as well as the adversarial domain. Empirical evaluations on Fashion-MNIST, SVHN, CIFAR-10 and CIFAR-100 demonstrate that ATDA can greatly improve the generalization of adversarial training and the smoothness of the learned models, and outperforms state-of-the-art methods on standard benchmark datasets. To show the transfer ability of our method, we also extend ATDA to the adversarial training on iterative attacks such as PGD-Adversial Training (PAT) and the defense performance is improved considerably.
The paper casts the problem of learning from adversarial examples to make models resistant to adversarial perturbations to a domain adaptation problem. The proposed method Adversarial training with Domain adapatation( ATDA) learns a representation that is invariant to clean and adversarial data achieving state of the art results on CIFAR. 
quality - Paper is well written, explanation of the mathematical parts are good, experimental quality can be much better.
clarity - the problem motivation as well as the methodology is clearly explained. the learning from the experiments are unclear and need more work.
originality - The casting of the problem as domain adaptation is original but from the experiments it was not conclusive as to how much benefit we get. 
significance of this work -  Current models being sensitive to adversarial perturbations is quite a big problem so the particular problem authors are trying to address is very significant.
pros
A good idea, enough experiments that indicate the benefit of casting this as a domain adaptation problem.
cons 
I feel, the authors should have extended the experiments to ImageNet which is a much larger dataset and validate the findings still hold, I feel the discussion section and comparison to other methods needs to be worked to be more thorough and to tease out the benefit of each of the various terms added to the loss functions as currently all we have is final numbers without much explanation and details. TSNE embeddings part is also very qualitative and while the plots indicate a better separation for ATDA, I feel authors should do more quantitative analysis on the embeddings instead of just qualitative plots.