Deep Learning
Finetuning Pretrained Transformers into Variational Autoencoders
Text variational autoencoders (VAEs) are notorious for posterior collapse, a phenomenon where the model's decoder learns to ignore signals from the encoder. Because posterior collapse is known to be exacerbated by expressive decoders, Transformers have seen limited adoption as components of text VAEs. Existing studies that incorporate Transformers into text VAEs (Li et al., 2020; Fang et al., 2021) mitigate posterior collapse using massive pretraining, a technique unavailable to most of the research community without extensive computing resources. We present a simple two-phase training scheme to convert a sequence-to-sequence Transformer into a VAE with just finetuning. The resulting language model is competitive with massively pretrained Transformer-based VAEs in some internal metrics while falling short on others. To facilitate training we comprehensively explore the impact of common posterior collapse alleviation techniques in the literature. We release our code for reproducability.
WeChat Neural Machine Translation Systems for WMT21
Zeng, Xianfeng, Liu, Yijin, Li, Ernan, Ran, Qiu, Meng, Fandong, Li, Peng, Xu, Jinan, Zhou, Jie
This paper introduces WeChat AI's participation in WMT 2021 shared news translation task on English->Chinese, English->Japanese, Japanese->English and English->German. Our systems are based on the Transformer (Vaswani et al., 2017) with several novel and effective variants. In our experiments, we employ data filtering, large-scale synthetic data generation (i.e., back-translation, knowledge distillation, forward-translation, iterative in-domain knowledge transfer), advanced finetuning approaches, and boosted Self-BLEU based model ensemble. Our constrained systems achieve 36.9, 46.9, 27.8 and 31.3 case-sensitive BLEU scores on English->Chinese, English->Japanese, Japanese->English and English->German, respectively. The BLEU scores of English->Chinese, English->Japanese and Japanese->English are the highest among all submissions, and that of English->German is the highest among all constrained submissions.
Video Abnormal Event Detection by Learning to Complete Visual Cloze Tests
Wang, Siqi, Yu, Guang, Cai, Zhiping, Liu, Xinwang, Zhu, En, Yin, Jianping, Liao, Qing
Video abnormal event detection (VAD) is a vital semi-supervised task that requires learning with only roughly labeled normal videos, as anomalies are often practically unavailable. Although deep neural networks (DNNs) enable great progress in VAD, existing solutions typically suffer from two issues: (1) The precise and comprehensive localization of video events is ignored. (2) The video semantics and temporal context are under-explored. To address those issues, we are motivated by the prevalent cloze test in education and propose a novel approach named visual cloze completion (VCC), which performs VAD by learning to complete "visual cloze tests" (VCTs). Specifically, VCC first localizes each video event and encloses it into a spatio-temporal cube (STC). To achieve both precise and comprehensive localization, appearance and motion are used as mutually complementary cues to mark the object region associated with each video event. For each marked region, a normalized patch sequence is extracted from temporally adjacent frames and stacked into the STC. By comparing each patch and the patch sequence of a STC to a visual "word" and "sentence" respectively, we can deliberately erase a certain "word" (patch) to yield a VCT. DNNs are then trained to infer the erased patch by video semantics, so as to complete the VCT. To fully exploit the temporal context, each patch in STC is alternatively erased to create multiple VCTs, and the erased patch's optical flow is also inferred to integrate richer motion clues. Meanwhile, a new DNN architecture is designed as a model-level solution to utilize video semantics and temporal context. Extensive experiments demonstrate that VCC achieves state-of-the-art VAD performance. Our codes and results are open at \url{https://github.com/yuguangnudt/VEC_VAD/tree/VCC}
Hindsight Value Function for Variance Reduction in Stochastic Dynamic Environment
Guo, Jiaming, Zhang, Rui, Zhang, Xishan, Peng, Shaohui, Yi, Qi, Du, Zidong, Hu, Xing, Guo, Qi, Chen, Yunji
Policy gradient methods are appealing in deep reinforcement learning but suffer from high variance of gradient estimate. To reduce the variance, the state value function is applied commonly. However, the effect of the state value function becomes limited in stochastic dynamic environments, where the unexpected state dynamics and rewards will increase the variance. In this paper, we propose to replace the state value function with a novel hindsight value function, which leverages the information from the future to reduce the variance of the gradient estimate for stochastic dynamic environments. Particularly, to obtain an ideally unbiased gradient estimate, we propose an information-theoretic approach, which optimizes the embeddings of the future to be independent of previous actions. In our experiments, we apply the proposed hindsight value function in stochastic dynamic environments, including discrete-action environments and continuous-action environments. Compared with the standard state value function, the proposed hindsight value function consistently reduces the variance, stabilizes the training, and improves the eventual policy.
Image Augmentation
If you are new to the field of deep learning, at some point in time you may have heard of the topic of image augmentation. This article will discuss what image augmentation is and implement it in three different python libraries i.e Keras, PyTorch, and augmentation (specifically for image augmentation). So the first question arises what is image augmentation or in general data augmentation. Augmentation is the action or process of making or becoming greater in size or amount. In deep learning, deep networks require a large amount of training data to generalize well and achieve good accuracy. But in some cases, image data is not large enough.
The Future of Livepeer
I have been asked this question a few times so I have decided to write this post about the current services of Livepeer and the future implementations Livepeer could bring to the decentralized world. This may be helpful for new comers that want to learn about Livepeer and have an idea of where Livepeer could take us in the future. But first we need to cover some important topics of where we are right now. First, let's look at the difference between Ethereum Mining and Video Mining. Livepeer has many possible services it could provide.
How AI is Changing the Construction Industry
Using artificial intelligence (AI) in the construction industry typically involves machine learning networks crunching data, data collection computer vision sensors, and the occasional physical robotics doing simple and repeatable manual tasks, such as laying bricks. While it seems construction involving AI is still in its infancy stage, there are still things to consider about the proper places where AI can find its place in the construction industry. Ultimately, AI is being used to make construction processes and projects more efficient and safe for human workers. There is some concern that AI will be removing human jobs, but so far that's not a concern that we've seen materialize. Like other industries involving artificial intelligence, AI is following the path of augmenting human tasks in order to speed up projects and make them safer.
Vision Transformers or Convolutional Neural Networks? Both!
The field of Computer Vision has for years been dominated by Convolutional Neural Networks (CNNs). Through the use of filters, these networks are able to generate simplified versions of the input image by creating feature maps that highlight the most relevant parts. These features are then used by a multi-layer perceptron to perform the desired classification. But recently this field has been incredibly revolutionized by the architecture of Vision Transformers (ViT), which through the mechanism of self-attention has proven to obtain excellent results on many tasks. If this in-depth educational content is useful for you, subscribe to our AI research mailing list to be alerted when we release new material.
Is DeepMind's new reinforcement learning system a step toward general AI?
All the sessions from Transform 2021 are available on-demand now. This article is part of our reviews of AI research papers, a series of posts that explore the latest findings in artificial intelligence. One of the key challenges of deep reinforcement learning models -- the kind of AI systems that have mastered Go, StarCraft 2, and other games -- is their inability to generalize their capabilities beyond their training domain. This limit makes it very hard to apply these systems to real-world settings, where situations are much more complicated and unpredictable than the environments where AI models are trained. But scientists at AI research lab DeepMind claim to have taken the "first steps to train an agent capable of playing many different games without needing human interaction data," according to a blog post about their new "open-ended learning" initiative. Their new project includes a 3D environment with realistic dynamics and deep reinforcement learning agents that can learn to solve a wide range of challenges.
MATLAB and Simulink Training
Get started quickly with the basics of MATLAB. Get started quickly with the basics of Simulink. Get started quickly using deep learning methods to perform image recognition. Master the basics of creating intelligent controllers that learn from experience. An interactive introduction to signal processing methods for spectral analysis.