Oceania
One-pass Multi-task Networks with Cross-task Guided Attention for Brain Tumor Segmentation
Zhou, Chenhong, Ding, Changxing, Wang, Xinchao, Lu, Zhentai, Tao, Dacheng
Class imbalance has been one of the major challenges for medical image segmentation. The model cascade (MC) strategy significantly alleviates class imbalance issue. In spite of its outstanding performance, this method leads to an undesired system complexity and meanwhile ignores the relevance among the models. To handle these flaws of MC, we propose in this paper a light-weight deep model, i.e., the One-pass Multi-task Network (OM-Net) to solve class imbalance better than MC and require only one-pass computation for brain tumor segmentation. First, OM-Net integrates the separate segmentation tasks into one deep model. Second, to optimize OM-Net more effectively, we take advantage of the correlation among tasks to design an online training data transfer strategy and a curriculum learning-based training strategy. Third, we further propose to share prediction results between tasks, which enables us to design a cross-task guided attention (CGA) module. With the guidance of prediction results provided by the previous task, CGA can adaptively recalibrate channel-wise feature responses based on the category-specific statistics. Finally, a simple yet effective post-processing method is introduced to refine the segmentation results of the proposed attention network. Extensive experiments are performed to justify the effectiveness of the proposed techniques. Most impressively, we achieve state-of-the-art performance on the BraTS 2015 and BraTS 2017 datasets. With the proposed approaches, we also won the joint third place in the BraTS 2018 challenge among 64 participating teams. We will make the code publicly available at https://github.com/chenhong-zhou/OM-Net.
Stay on the Path: Instruction Fidelity in Vision-and-Language Navigation
Jain, Vihan, Magalhaes, Gabriel, Ku, Alexander, Vaswani, Ashish, Ie, Eugene, Baldridge, Jason
Advances in learning and representations have reinvigorated work that connects language to other modalities. A particularly exciting direction is Vision-and-Language Navigation (VLN), in which agents interpret natural language instructions and visual scenes to move through environments and reach goals. Despite recent progress, current research leaves unclear how much of a role language understanding plays in this task, especially because dominant evaluation metrics have focused on Figure 1: It's the journey, not just the goal. To give goal completion rather than the sequence of actions language its due place in VLN, we compose paths in corresponding to the instructions. Here, the R2R dataset to create longer, twistier R4R paths we highlight shortcomings of current metrics (blue). Under commonly used metrics, agents that head for the Room-to-Room dataset (Anderson et al., straight to the goal (red) are not penalized for ignoring 2018b) and propose a new metric, Coverage the language instructions: for instance, SPL yields a weighted by Length Score (CLS). We also show perfect 1.0 score for the red and only 0.17 for the orange that the existing paths in the dataset are not path. In contrast, our proposed CLS metric measures ideal for evaluating instruction following because fidelity to the reference path, strongly preferring the they are direct-to-goal shortest paths.
Artificial intelligence's role in news and information needs scrutiny
The role artificial intelligence plays in the information Australians have access to needs transparency and regulatory oversight to mitigate "filter bubbles" โ where people aren't challenged by alternative viewpoints โ and other adverse outcomes. Algorithmic control over news and information, via Google Search and Facebook Newsfeed, is one of the key focus points for industry lobbying Free TV in its submission to the Department of Industry, Innovation and Science's discussion paper on Artificial Intelligence: Australia's Ethics Framework. AI has a growing role in how humans access content. Artificial intelligence will play an increasingly important role in everyday lives as inventions such as driverless cars become more of a reality. However, the department notes an AI ethics framework is not about changing laws or ethical standards, it is about making sure those already existing can be applied to AI. "The point of this submission was there is this whole area that's very important to the fabric of society, which is news, and that wasn't something that was focused on in the paper," Free TV chief executive Bridget Fair said.
One-Way Prototypical Networks
Few-shot models have become a popular topic of research in the past years. They offer the possibility to determine class belongings for unseen examples using just a handful of examples for each class. Such models are trained on a wide range of classes and their respective examples, learning a decision metric in the process. Types of few-shot models include matching networks and prototypical networks. We show a new way of training prototypical few-shot models for just a single class. These models have the ability to predict the likelihood of an unseen query belonging to a group of examples without any given counterexamples. The difficulty here lies in the fact that no relative distance to other classes can be calculated via softmax. We solve this problem by introducing a "null class" centered around zero, and enforcing centering with batch normalization. Trained on the commonly used Omniglot data set, we obtain a classification accuracy of .98 on the matched test set, and of .8 on unmatched MNIST data. On the more complex MiniImageNet data set, test accuracy is .8. In addition, we propose a novel Gaussian layer for distance calculation in a prototypical network, which takes the support examples' distribution rather than just their centroid into account. This extension shows promising results when a higher number of support examples is available.
A Perspective on Objects and Systematic Generalization in Model-Based RL
van Steenkiste, Sjoerd, Greff, Klaus, Schmidhuber, Jรผrgen
In order to meet the diverse challenges in solving many real-world problems, an intelligent agent has to be able to dynamically construct a model of its environment. Objects facilitate the modular reuse of prior knowledge and the combinatorial construction of such models. In this work, we argue that dynamically bound features (objects) do not simply emerge in connectionist models of the world. We identify several requirements that need to be fulfilled in overcoming this limitation and highlight corresponding inductive biases.
Continual learning with hypernetworks
von Oswald, Johannes, Henning, Christian, Sacramento, Joรฃo, Grewe, Benjamin F.
Artificial neural networks suffer from catastrophic forgetting when they are sequentially trained on multiple tasks. To overcome this problem, we present a novel approach based on task-conditioned hypernetworks, i.e., networks that generate the weights of a target model based on task identity. Continual learning (CL) is less difficult for this class of models thanks to a simple key observation: instead of relying on recalling the input-output relations of all previously seen data, task-conditioned hypernetworks only require rehearsing previous weight realizations, which can be maintained in memory using a simple regularizer. Besides achieving good performance on standard CL benchmarks, additional experiments on long task sequences reveal that task-conditioned hypernetworks display an unprecedented capacity to retain previous memories. Notably, such long memory lifetimes are achieved in a compressive regime, when the number of trainable weights is comparable or smaller than target network size. We provide insight into the structure of low-dimensional task embedding spaces (the input space of the hypernetwork) and show that task-conditioned hypernetworks demonstrate transfer learning properties. Finally, forward information transfer is further supported by empirical results on a challenging CL benchmark based on the CIFAR-10/100 image datasets.
Hybrid Machine Learning Forecasts for the FIFA Women's World Cup 2019
Groll, Andreas, Ley, Christophe, Schauberger, Gunther, Van Eetvelde, Hans, Zeileis, Achim
In this work, we combine two different ranking methods together with several other predictors in a joint random forest approach for the scores of soccer matches. The first ranking method is based on the bookmaker consensus, the second ranking method estimates adequate ability parameters that reflect the current strength of the teams best. The proposed combined approach is then applied to the data from the two previous FIFA Women's World Cups 2011 and 2015. Finally, based on the resulting estimates, the FIFA Women's World Cup 2019 is simulated repeatedly and winning probabilities are obtained for all teams. The model clearly favors the defending champion USA before the host France.
Neural Network-based Object Classification by Known and Unknown Features (Based on Text Queries)
Artemov, A., Bolokhov, I., Kem, D., Khasenevich, I.
The article presents a method that improves the quality of classification of objects described by a combination of known and unknown features. The method is based on modernized Informational Neurobayesian Approach with consideration of unknown features. The proposed method was developed and trained on 1500 text queries of Promobot users in Russian to classify them into 20 categories (classes). As a result, the use of the method allowed to completely solve the problem of misclassification for queries with combining known and unknown features of the model. The theoretical substantiation of the method is presented by the formulated and proved theorem On the Model with Limited Knowledge. It states, that in conditions of limited data, an equal number of equally unknown features of an object cannot have different significance for the classification problem. Keywords: Informational Neurobayesian Approach, Neural describes a car, a race car, or an excavator. Unknown words Networks, Unknown Features, Machine Learning, NLP may bring us closer or farther from these categories. For example, "super-fast"- identifies a race car, and "a dipper" resembles an excavator.
A Fast-Optimal Guaranteed Algorithm For Learning Sub-Interval Relationships in Time Series
Agrawal, Saurabh, Verma, Saurabh, Karpatne, Anuj, Liess, Stefan, Chatterjee, Snigdhansu, Kumar, Vipin
Traditional approaches focus on finding relationships between two entire time series, however, many interesting relationships exist in small sub-intervals of time and remain feeble during other sub-intervals. We define the notion of a sub-interval relationship (SIR) to capture such interactions that are prominent only in certain sub-intervals of time. To that end, we propose a fast-optimal guaranteed algorithm to find most interesting SIR relationship in a pair of time series. Lastly, we demonstrate the utility of our method in climate science domain based on a real-world dataset along with its scalability scope and obtain useful domain insights.
Prototype Propagation Networks (PPN) for Weakly-supervised Few-shot Learning on Category Graph
Liu, Lu, Zhou, Tianyi, Long, Guodong, Jiang, Jing, Yao, Lina, Zhang, Chengqi
A variety of machine learning applications expect to achieve rapid learning from a limited number of labeled data. However, the success of most current models is the result of heavy training on big data. Meta-learning addresses this problem by extracting common knowledge across different tasks that can be quickly adapted to new tasks. However, they do not fully explore weakly-supervised information, which is usually free or cheap to collect. In this paper, we show that weakly-labeled data can significantly improve the performance of meta-learning on few-shot classification. We propose prototype propagation network (PPN) trained on few-shot tasks together with data annotated by coarse-label. Given a category graph of the targeted fine-classes and some weakly-labeled coarse-classes, PPN learns an attention mechanism which propagates the prototype of one class to another on the graph, so that the K-nearest neighbor (KNN) classifier defined on the propagated prototypes results in high accuracy across different few-shot tasks. The training tasks are generated by subgraph sampling, and the training objective is obtained by accumulating the level-wise classification loss on the subgraph. The resulting graph of prototypes can be continually re-used and updated for new tasks and classes. We also introduce two practical test/inference settings which differ according to whether the test task can leverage any weakly-supervised information as in training. On two benchmarks, PPN significantly outperforms most recent few-shot learning methods in different settings, even when they are also allowed to train on weakly-labeled data.