In this paper, we explore the inclusion of latent random variables into the hidden state of a recurrent neural network (RNN) by combining the elements of the variational autoencoder. We argue that through the use of high-level latent random variables, the variational RNN (VRNN) 1 can model the kind of variability observed in highly structured sequential data such as natural speech. We empirically evaluate the proposed model against other related sequential models on four speech datasets and one handwriting dataset. Our results show the important roles that latent random variables can play in the RNN dynamics.

The standard recurrent neural network language model (rnnlm) generates sentences one word at a time and does not work from an explicit global sentence representation. In this work, we introduce and study an rnn-based variational autoencoder generative model that incorporates distributed latent representations of entire sentences. This factorization allows it to explicitly model holistic properties of sentences such as style, topic, and high-level syntactic features. Samples from the prior over these sentence representations remarkably produce diverse and well-formed sentences through simple deterministic decoding. By examining paths through this latent space, we are able to generate coherent novel sentences that interpolate between known sentences. We present techniques for solving the difficult learning problem presented by this model, demonstrate its effectiveness in imputing missing words, explore many interesting properties of the model's latent sentence space, and present negative results on the use of the model in language modeling.

This paper introduces WaveNet, a deep neural network for generating raw audio waveforms. The model is fully probabilistic and autoregressive, with the predictive distribution for each audio sample conditioned on all previous ones; nonetheless we show that it can be efficiently trained on data with tens of thousands of samples per second of audio. When applied to text-to-speech, it yields state-ofthe-art performance, with human listeners rating it as significantly more natural sounding than the best parametric and concatenative systems for both English and Mandarin. A single WaveNet can capture the characteristics of many different speakers with equal fidelity, and can switch between them by conditioning on the speaker identity. When trained to model music, we find that it generates novel and often highly realistic musical fragments. We also show that it can be employed as a discriminative model, returning promising results for phoneme recognition.

近似复杂的概率密度是现代统计中的核心问题。在本文中，我们介绍了变分推理（VI）的概念，这是一种机器学习中的流行方法，该方法使用优化技术来估计复杂的概率密度。此属性允许VI汇聚速度比经典方法更快，例如Markov Chain Monte Carlo采样。概念上，VI通过选择一个概率密度函数，然后找到最接近实际概率密度的家庭 - 通常使用Kullback-Leibler（KL）发散作为优化度量。我们介绍了缩窄的证据，以促进近似的概率密度，我们审查了平均场变分推理背后的想法。最后，我们讨论VI对变分式自动编码器（VAE）和VAE-生成的对抗网络（VAE-GAN）的应用。用本文，我们的目标是解释VI的概念，并通过这种方法协助协助。

Methods based on ordinary differential equations (ODEs) are widely used to build generative models of time-series. In addition to high computational overhead due to explicitly computing hidden states recurrence, existing ODE-based models fall short in learning sequence data with sharp transitions - common in many real-world systems - due to numerical challenges during optimization. In this work, we propose LS4, a generative model for sequences with latent variables evolving according to a state space ODE to increase modeling capacity. Inspired by recent deep state space models (S4), we achieve speedups by leveraging a convolutional representation of LS4 which bypasses the explicit evaluation of hidden states. We show that LS4 significantly outperforms previous continuous-time generative models in terms of marginal distribution, classification, and prediction scores on real-world datasets in the Monash Forecasting Repository, and is capable of modeling highly stochastic data with sharp temporal transitions. LS4 sets state-of-the-art for continuous-time latent generative models, with significant improvement of mean squared error and tighter variational lower bounds on irregularly-sampled datasets, while also being x100 faster than other baselines on long sequences.

The task of video prediction and generation is known to be notoriously difficult, with the research in this area largely limited to short-term predictions. Though plagued with noise and stochasticity, videos consist of features that are organised in a spatiotemporal hierarchy, different features possessing different temporal dynamics. In this paper, we introduce Dynamic Latent Hierarchy (DLH) -- a deep hierarchical latent model that represents videos as a hierarchy of latent states that evolve over separate and fluid timescales. Each latent state is a mixture distribution with two components, representing the immediate past and the predicted future, causing the model to learn transitions only between sufficiently dissimilar states, while clustering temporally persistent states closer together. Using this unique property, DLH naturally discovers the spatiotemporal structure of a dataset and learns disentangled representations across its hierarchy. We hypothesise that this simplifies the task of modeling temporal dynamics of a video, improves the learning of long-term dependencies, and reduces error accumulation. As evidence, we demonstrate that DLH outperforms state-of-the-art benchmarks in video prediction, is able to better represent stochasticity, as well as to dynamically adjust its hierarchical and temporal structure. Our paper shows, among other things, how progress in representation learning can translate into progress in prediction tasks.

概率分布允许从业者发现数据中的隐藏结构，并构建模型，以使用有限的数据解决监督的学习问题。该报告的重点是变异自动编码器，这是一种学习大型复杂数据集概率分布的方法。该报告提供了对变异自动编码器的理论理解，并巩固了该领域的当前研究。该报告分为多个章节，第一章介绍了问题，描述了变异自动编码器并标识了该领域的关键研究方向。第2、3、4和5章深入研究了每个关键研究领域的细节。第6章总结了报告，并提出了未来工作的指示。具有机器学习基本思想但想了解机器学习研究中的一般主题的读者可以从报告中受益。该报告解释了有关学习概率分布的中心思想，人们为使这种危险做些什么，并介绍了有关当前如何应用深度学习的细节。该报告还为希望为这个子场做出贡献的人提供了温和的介绍。

The framework of normalizing flows provides a general strategy for flexible variational inference of posteriors over latent variables. We propose a new type of normalizing flow, inverse autoregressive flow (IAF), that, in contrast to earlier published flows, scales well to high-dimensional latent spaces. The proposed flow consists of a chain of invertible transformations, where each transformation is based on an autoregressive neural network. In experiments, we show that IAF significantly improves upon diagonal Gaussian approximate posteriors. In addition, we demonstrate that a novel type of variational autoencoder, coupled with IAF, is competitive with neural autoregressive models in terms of attained log-likelihood on natural images, while allowing significantly faster synthesis.

配备具有推断人类意图的能力的机器人是有效合作的重要前提。对于这种目标的大多数计算方法采用了概率的推理，以回收机器人感知状态的“意图”的分布。然而，这些方法通常假设人类意图的特定任务概念（例如标记目标）是先验的。为了克服这一限制，我们提出了解离序列聚类变分性Autiachoder（Discvae），该群集框架可以用于以无监督的方式学习意图的这种分布。 DiscVae利用最近在无监督的学习方面的进步导出了顺序数据的解除不诚格潜在表示，从时间不变的全局方面分离时变化的本地特征。虽然与前面的解剖学框架不同，但是所提出的变体也涉及分立变量，以形成潜在混合模型，并使全局序列概念进行聚类，例如，观察到人类行为的意图。为了评估Discvae，首先使用弹跳数字和2D动画的视频数据集来验证其从未标记序列发现类的容量。然后，我们从机器人轮椅上进行的现实世界机器人交互实验报告结果。我们的调查结果引入了推断离散变量如何与人类意图一致，从而用于改善协作设置的帮助，例如共享控制。

In this paper we compare different types of recurrent units in recurrent neural networks (RNNs). Especially, we focus on more sophisticated units that implement a gating mechanism, such as a long short-term memory (LSTM) unit and a recently proposed gated recurrent unit (GRU). We evaluate these recurrent units on the tasks of polyphonic music modeling and speech signal modeling. Our experiments revealed that these advanced recurrent units are indeed better than more traditional recurrent units such as tanh units. Also, we found GRU to be comparable to LSTM.

我们引入了变分状态空间过滤器（VSSF），这是从原始像素的无监督学习，识别和过滤潜伏的Larkov状态空间模型的新方法。在异构传感器配置下，我们为潜在的状态空间推断提出了理论上的声音框架。得到的模型可以集成训练期间使用的传感器测量的任意子集，从而实现半监督状态表示的学习，从而强制执行学习潜在状态空间的某些组件来达成可解释的测量。从此框架中，我们派生了L-VSSF，这是一个用线性潜在动态和高斯分布参数化的本模型的明确实例化。我们通过实验演示了L-VSSF在几个不同的测试环境中过滤超出训练数据集的序列长度的潜伏空间的能力。

控制模型生成不同类别的文本是一个挑战的任务，越来越多的关注。最近，生成的对抗性网（GAN）在类别文本生成中显示了有希望的结果。然而，由GAN产生的文本通常遭受模式崩溃和培训不稳定的问题。为了避免上述问题，我们提出了一种名为Categary Impare变分频神经网络（Catvrnn）的小说模型，这是由多任务学习的启发。在我们的模型中，生成和分类是同时培训的，旨在产生不同类别的文本。此外，当分类任务适当时，使用多任务学习可以提高生成文本的质量。并且我们提出了一种初始化Catvrnn的隐藏状态的函数，以强制模型生成特定类别的文本。三个数据集上的实验结果表明，我们的模型可以在基于几种最先进的文本生成方法中，以类别的基于GAN的生成文本的质量。

The success of machine learning algorithms generally depends on data representation, and we hypothesize that this is because different representations can entangle and hide more or less the different explanatory factors of variation behind the data. Although specific domain knowledge can be used to help design representations, learning with generic priors can also be used, and the quest for AI is motivating the design of more powerful representation-learning algorithms implementing such priors. This paper reviews recent work in the area of unsupervised feature learning and deep learning, covering advances in probabilistic models, auto-encoders, manifold learning, and deep networks. This motivates longer-term unanswered questions about the appropriate objectives for learning good representations, for computing representations (i.e., inference), and the geometrical connections between representation learning, density estimation and manifold learning.

扩散模型显示出令人难以置信的能力作为生成模型。实际上，它们为文本条件形成的图像生成（例如Imagen和dall-e2）提供了当前最新模型的启动基于观点。我们首先推导了变异扩散模型（VDM）作为马尔可夫分层变异自动编码器的特殊情况，其中三个关键假设可实现ELBO的可拖动计算和可扩展的优化。然后，我们证明，优化VDM归结为学习神经网络以预测三个潜在目标之一：来自任何任意噪声的原始源输入，任何任意噪声输入的原始源噪声或噪声的得分函数输入任何任意噪声水平。然后，我们更深入地研究学习分数函数的含义，并将扩散模型的变异透视图与通过Tweedie的公式明确地与基于得分的生成建模的角度联系起来。最后，我们涵盖了如何通过指导使用扩散模型学习条件分布的方法。

How can we perform efficient inference and learning in directed probabilistic models, in the presence of continuous latent variables with intractable posterior distributions, and large datasets? We introduce a stochastic variational inference and learning algorithm that scales to large datasets and, under some mild differentiability conditions, even works in the intractable case. Our contributions is two-fold. First, we show that a reparameterization of the variational lower bound yields a lower bound estimator that can be straightforwardly optimized using standard stochastic gradient methods. Second, we show that for i.i.d. datasets with continuous latent variables per datapoint, posterior inference can be made especially efficient by fitting an approximate inference model (also called a recognition model) to the intractable posterior using the proposed lower bound estimator. Theoretical advantages are reflected in experimental results.

Learning useful representations without supervision remains a key challenge in machine learning. In this paper, we propose a simple yet powerful generative model that learns such discrete representations. Our model, the Vector Quantised-Variational AutoEncoder (VQ-VAE), differs from VAEs in two key ways: the encoder network outputs discrete, rather than continuous, codes; and the prior is learnt rather than static. In order to learn a discrete latent representation, we incorporate ideas from vector quantisation (VQ). Using the VQ method allows the model to circumvent issues of "posterior collapse" --where the latents are ignored when they are paired with a powerful autoregressive decoder --typically observed in the VAE framework. Pairing these representations with an autoregressive prior, the model can generate high quality images, videos, and speech as well as doing high quality speaker conversion and unsupervised learning of phonemes, providing further evidence of the utility of the learnt representations.

自动编码变化贝叶斯（AEVB）是一种用于拟合潜在变量模型（无监督学习的有前途的方向）的强大而通用的算法，并且是训练变量自动编码器（VAE）的众所周知的。在本教程中，我们专注于从经典的期望最大化（EM）算法中激励AEVB，而不是确定性自动编码器。尽管自然而有些不言而喻，但在最近的深度学习文献中并未强调EM与AEVB之间的联系，我们认为强调这种联系可以改善社区对AEVB的理解。特别是，我们发现（1）优化有关推理参数的证据下限（ELBO）作为近似E-step，并且（2）优化ELBO相对于生成参数作为近似M-step；然后，与AEVB中的同时进行同时进行，然后同时拧紧并推动Elbo。我们讨论如何将近似E-Step解释为执行变异推断。详细讨论了诸如摊销和修复技巧之类的重要概念。最后，我们从划痕中得出了非深度和几个深层变量模型的AEVB训练程序，包括VAE，有条件的VAE，高斯混合物VAE和变异RNN。我们希望读者能够将AEVB认识为一种通用算法，可用于拟合广泛的潜在变量模型（不仅仅是VAE），并将AEVB应用于自己的研究领域中出现的此类模型。所有纳入型号的Pytorch代码均可公开使用。

深度学习算法的兴起引领许多研究人员使用经典信号处理方法来发声。深度学习模型已经实现了富有富有的语音合成，现实的声音纹理和虚拟乐器的音符。然而，最合适的深度学习架构仍在调查中。架构的选择紧密耦合到音频表示。声音的原始波形可以太密集和丰富，用于深入学习模型，以有效处理 - 复杂性提高培训时间和计算成本。此外，它不代表声音以其所感知的方式。因此，在许多情况下，原始音频已经使用上采样，特征提取，甚至采用波形的更高级别的图示来转换为压缩和更有意义的形式。此外，研究了所选择的形式，另外的调节表示，不同的模型架构以及用于评估重建声音的许多度量的条件。本文概述了应用于使用深度学习的声音合成的音频表示。此外，它呈现了使用深度学习模型开发和评估声音合成架构的最重要方法，始终根据音频表示。

医疗数据集通常由噪声和缺失数据损坏。这些缺失的模式通常被认为是完全随机的，而是在医学场景中，现实是，这些模式由于在一些时间或数据被收集的不alaled的不均匀方式中被收集的传感器而发生突发。本文建议使用异构数据类型和使用顺序变化自动码器（VAES）来模拟医疗数据记录和突发的缺失数据。特别是，我们提出了一种新的方法，SHI-VAE，其扩展了VAE的能力，使VAE的顺序数据流缺失了观察。我们将我们的模型与精密护理单元数据库（ICU）中的最先进的解决方案进行比较和被动人类监测的数据集。此外，我们发现诸如RMSE的标准错误指标不能得出足够的决定性，以评估时间模型，并包括在我们分析地面真理和算中信号之间的互相关。我们表明Shi-VAE在使用两个指标方面实现了最佳性能，而不是GP-VAE模型的计算复杂性较低，这是用于医疗记录的最先进的方法。