Machine learning methods may have the potential to significantly accelerate drug discovery. However, the increasing rate of new methodological approaches being published in the literature raises the fundamental question of how models should be benchmarked and validated. We reanalyze the data generated by a recently published large-scale comparison of machine learning models for bioactivity prediction and arrive at a somewhat different conclusion. We show that the performance of support vector machines is competitive with that of deep learning methods. Additionally, using a series of numerical experiments, we question the relevance of area under the receiver operating characteristic curve as a metric in virtual screening, and instead suggest that area under the precision-recall curve should be used in conjunction with the receiver operating characteristic. Our numerical experiments also highlight challenges in estimating the uncertainty in model performance via scaffold-split nested cross validation.

Graph Neural Networks (GNNs) have boosted the performance of many graph related tasks such as node classification and graph classification. Recent researches show that graph neural networks are vulnerable to adversarial attacks, which deliberately add carefully created unnoticeable perturbation to the graph structure. The perturbation is usually created by adding/deleting a few edges, which might be noticeable even when the number of edges modified is small. In this paper, we propose a graph rewiring operation which affects the graph in a less noticeable way compared to adding/deleting edges. We then use reinforcement learning to learn the attack strategy based on the proposed rewiring operation. Experiments on real world graphs demonstrate the effectiveness of the proposed framework. To understand the proposed framework, we further analyze how its generated perturbation to the graph structure affects the output of the target model.

Envisioning a new imaginative idea together is a popular human need. Imagining together as a team can often lead to breakthrough ideas, but the collaboration effort can also be challenging, especially when the team members are separated by time and space. What if there is a AI that can assist the team to collaboratively envision new ideas?. Is it possible to develop a working model of such an AI? This paper aims to design such an intelligence. This paper proposes a approach to design a creative and collaborative intelligence by employing a form of distributed machine learning approach called Federated Learning along with fusion on Generative Adversarial Networks, GAN. This collaborative creative AI presents a new paradigm in AI, one that lets a team of two or more to come together to imagine and envision ideas that synergies well with interests of all members of the team. In short, this paper explores the design of a novel type of AI paradigm, called Federated AI Imagination, one that lets geographically distributed teams to collaboratively imagine.

Soil moisture is an important variable that determines floods, vegetation health, agriculture productivity, and land surface feedbacks to the atmosphere, etc. Accurately modeling soil moisture has important implications in both weather and climate models. The recently available satellite-based observations give us a unique opportunity to build data-driven models to predict soil moisture instead of using land surface models, but previously there was no uncertainty estimate. We tested Monte Carlo dropout (MCD) with an aleatoric term for our long short-term memory models for this problem, and asked if the uncertainty terms behave as they were argued to. We show that the method successfully captures the predictive error after tuning a hyperparameter on a representative training dataset. We show the MCD uncertainty estimate, as previously argued, does detect dissimilarity.

We improve the over-parametrization size over two beautiful results [Li and Liang' 2018] and [Du, Zhai, Poczos and Singh' 2019] in deep learning theory.

Deep neural networks have been proved efficient for medical image denoising. Current training methods require both noisy and clean images. However, clean images cannot be acquired for many practical medical applications due to naturally noisy signal, such as dynamic imaging, spectral computed tomography, arterial spin labeling magnetic resonance imaging, etc. In this paper we proposed a training method which learned denoising neural networks from noisy training samples only. Training data in the acquisition domain was split to two subsets and the network was trained to map one noisy set to the other. A consensus loss function was further proposed to efficiently combine the outputs from both subsets. A mathematical proof was provided that the proposed training scheme was equivalent to training with noisy and clean samples when the noise in the two subsets was uncorrelated and zero-mean. The method was validated on Low-dose CT Challenge dataset and NYU MRI dataset and achieved improved performance compared to existing unsupervised methods.

Although gradient-based saliency maps are popular methods for deep learning interpretation, they can be extremely vulnerable to adversarial attacks. This is worrisome especially due to the lack of practical defenses for protecting deep learning interpretations against attacks. In this paper, we address this problem and provide two defense methods for deep learning interpretation. First, we show that a sparsified version of the popular SmoothGrad method, which computes the average saliency maps over random perturbations of the input, is certifiably robust against adversarial perturbations. We obtain this result by extending recent bounds for certifiably robust smooth classifiers to the interpretation setting. Experiments on ImageNet samples validate our theory. Second, we introduce an adversarial training approach to further robustify deep learning interpretation by adding a regularization term to penalize the inconsistency of saliency maps between normal and crafted adversarial samples. Empirically, we observe that this approach not only improves the robustness of deep learning interpretation to adversarial attacks, but it also improves the quality of the gradient-based saliency maps.

We present a transfer learning strategy which fundamentally relies on Bayesian deep learning and the ability to represent Exploration and adaptation to new tasks in a transfer a distribution over functions, as in (Bachman et al., 2018) learning setup is a central challenge in reinforcement (Garnelo et al., 2018). Bayesian methods rely on modeling learning. In this work, we build on the uncertainty over value functions to represent the agent's the idea of modeling a distribution over policies belief of the environment. Recent work has shown that in a Bayesian deep reinforcement learning setup neural networks can be used to represent an uncertainty to propose a transfer strategy. Recent works over the space of all possible functions (Bachman et al., have shown to induce diversity in the learned 2018). The idea of modeling a distribution over functions policies by maximizing the entropy of a distribution can be adapted in the RL setting to model a distribution over of policies (Bachman et al., 2018; Garnelo policies, such that we can also maximize the entropy over et al., 2018) and thus, we postulate that our this distribution of policies. This is similar to maximum proposed approach leads to faster exploration resulting entropy exploration in RL, where instead of local entropy in improved transfer learning. We support maximization, recent work maximizes the global entropy our hypothesis by demonstrating favorable over the space of all possible sub-optimal policies.

After learning a concept, humans are also able to continually generalize their learned concepts to new domains by observing only a few labeled instances without any interference with the past learned knowledge. In contrast, learning concepts efficiently in a continual learning setting remains an open challenge for current Artificial Intelligence algorithms as persistent model retraining is necessary. Inspired by the Parallel Distributed Processing learning and the Complementary Learning Systems theories, we develop a computational model that is able to expand its previously learned concepts efficiently to new domains using a few labeled samples. We couple the new form of a concept to its past learned forms in an embedding space for effective continual learning. Doing so, a generative distribution is learned such that it is shared across the tasks in the embedding space and models the abstract concepts. This procedure enables the model to generate pseudo-data points to replay the past experience to tackle catastrophic forgetting.

In recent years, implicit regularization from various optimization algorithms plays a crucial role in the generalizatiion abilities in training deep neural networks [Salakhutdinov and Srebro, 2015, Neyshabur et al., 2015, Keskar et al., 2016, Neyshabur et al., 2017, Zhang et al., 2017]. For example, in underdetermined problems where the number of parameters is larger than the number of training examples, many global optimum fail to exhibit good generalization properties, however, a specific optimization algorithm (such as gradient descent) does converge to a particular optimum that generalize well, although no explicit regularization is enforced when training the model.