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DDN: Dual-domain Dynamic Normalization for Non-stationary Time Series Forecasting

Neural Information Processing Systems

Deep neural networks (DNNs) have recently achieved remarkable advancements in time series forecasting (TSF) due to their powerful ability of sequence dependence modeling. To date, existing DNN-based TSF methods still suffer from unreliable predictions for real-world data due to its non-stationarity characteristics, i.e., data distribution varies quickly over time. To mitigate this issue, several normalization methods (e.g., SAN) have recently been specifically designed by normalization in a fixed period/window in the time domain. However, these methods still struggle to capture distribution variations, due to the complex time patterns of time series in the time domain. Based on the fact that wavelet transform can decompose time series into a linear combination of different frequencies, which exhibits distribution variations with time-varying periods, we propose a novel Dual-domain Dynamic Normalization (DDN) to dynamically capture distribution variations in both time and frequency domains. Specifically, our DDN tries to eliminate the non-stationarity of time series via both frequency and time domain normalization in a sliding window way. Besides, our DDN can serve as a plug-in-play module, and thus can be easily incorporated into other forecasting models. Extensive experiments on public benchmark datasets under different forecasting models demonstrate the superiority of our DDN over other normalization methods. Code will be made available following the review process.


Data-Distill-Net: A Data Distillation Approach Tailored for Reply-based Continual Learning

Liao, Wenyang, Wang, Quanziang, Wu, Yichen, Wang, Renzhen, Meng, Deyu

arXiv.org Artificial Intelligence

Replay-based continual learning (CL) methods assume that models trained on a small subset can also effectively minimize the empirical risk of the complete dataset. These methods maintain a memory buffer that stores a sampled subset of data from previous tasks to consolidate past knowledge. However, this assumption is not guaranteed in practice due to the limited capacity of the memory buffer and the heuristic criteria used for buffer data selection. To address this issue, we propose a new dataset distillation framework tailored for CL, which maintains a learnable memory buffer to distill the global information from the current task data and accumulated knowledge preserved in the previous memory buffer. Moreover, to avoid the computational overhead and overfitting risks associated with parameterizing the entire buffer during distillation, we introduce a lightweight distillation module that can achieve global information distillation solely by generating learnable soft labels for the memory buffer data. Extensive experiments show that, our method can achieve competitive results and effectively mitigates forgetting across various datasets. The source code will be publicly available.


DDN: Dual-domain Dynamic Normalization for Non-stationary Time Series Forecasting

Neural Information Processing Systems

Deep neural networks (DNNs) have recently achieved remarkable advancements in time series forecasting (TSF) due to their powerful ability of sequence dependence modeling. To date, existing DNN-based TSF methods still suffer from unreliable predictions for real-world data due to its non-stationarity characteristics, i.e., data distribution varies quickly over time. To mitigate this issue, several normalization methods (e.g., SAN) have recently been specifically designed by normalization in a fixed period/window in the time domain. However, these methods still struggle to capture distribution variations, due to the complex time patterns of time series in the time domain. Based on the fact that wavelet transform can decompose time series into a linear combination of different frequencies, which exhibits distribution variations with time-varying periods, we propose a novel Dual-domain Dynamic Normalization (DDN) to dynamically capture distribution variations in both time and frequency domains.


Double Distillation Network for Multi-Agent Reinforcement Learning

Zhou, Yang, Wang, Siying, Chen, Wenyu, Zhang, Ruoning, Zhao, Zhitong, Zhang, Zixuan

arXiv.org Artificial Intelligence

Multi-agent reinforcement learning typically employs a centralized training-decentralized execution (CTDE) framework to alleviate the non-stationarity in environment. However, the partial observability during execution may lead to cumulative gap errors gathered by agents, impairing the training of effective collaborative policies. To overcome this challenge, we introduce the Double Distillation Network (DDN), which incorporates two distillation modules aimed at enhancing robust coordination and facilitating the collaboration process under constrained information. The external distillation module uses a global guiding network and a local policy network, employing distillation to reconcile the gap between global training and local execution. In addition, the internal distillation module introduces intrinsic rewards, drawn from state information, to enhance the exploration capabilities of agents. Extensive experiments demonstrate that DDN significantly improves performance across multiple scenarios.


Deep Dependency Networks and Advanced Inference Schemes for Multi-Label Classification

Arya, Shivvrat, Xiang, Yu, Gogate, Vibhav

arXiv.org Machine Learning

We present a unified framework called deep dependency networks (DDNs) that combines dependency networks and deep learning architectures for multi-label classification, with a particular emphasis on image and video data. The primary advantage of dependency networks is their ease of training, in contrast to other probabilistic graphical models like Markov networks. In particular, when combined with deep learning architectures, they provide an intuitive, easy-to-use loss function for multi-label classification. A drawback of DDNs compared to Markov networks is their lack of advanced inference schemes, necessitating the use of Gibbs sampling. To address this challenge, we propose novel inference schemes based on local search and integer linear programming for computing the most likely assignment to the labels given observations. We evaluate our novel methods on three video datasets (Charades, TACoS, Wetlab) and three image datasets (MS-COCO, PASCAL VOC, NUS-WIDE), comparing their performance with (a) basic neural architectures and (b) neural architectures combined with Markov networks equipped with advanced inference and learning techniques. Our results demonstrate the superiority of our new DDN methods over the two competing approaches.


Discrete Distribution Networks

Yang, Lei

arXiv.org Artificial Intelligence

We introduce a novel generative model, the Discrete Distribution Networks (DDN), that approximates data distribution using hierarchical discrete distributions. We posit that since the features within a network inherently contain distributional information, liberating the network from a single output to concurrently generate multiple samples proves to be highly effective. Therefore, DDN fits the target distribution, including continuous ones, by generating multiple discrete sample points. To capture finer details of the target data, DDN selects the output that is closest to the Ground Truth (GT) from the coarse results generated in the first layer. This selected output is then fed back into the network as a condition for the second layer, thereby generating new outputs more similar to the GT. As the number of DDN layers increases, the representational space of the outputs expands exponentially, and the generated samples become increasingly similar to the GT. This hierarchical output pattern of discrete distributions endows DDN with two intriguing properties: highly compressed representation and more general zero-shot conditional generation. We demonstrate the efficacy of DDN and these intriguing properties through experiments on CIFAR-10 and FFHQ.


Deep Dependency Networks for Multi-Label Classification

Arya, Shivvrat, Xiang, Yu, Gogate, Vibhav

arXiv.org Artificial Intelligence

We propose a simple approach which combines the strengths of probabilistic graphical models and deep learning architectures for solving the multi-label classification task, focusing specifically on image and video data. First, we show that the performance of previous approaches that combine Markov Random Fields with neural networks can be modestly improved by leveraging more powerful methods such as iterative join graph propagation, integer linear programming, and $\ell_1$ regularization-based structure learning. Then we propose a new modeling framework called deep dependency networks, which augments a dependency network, a model that is easy to train and learns more accurate dependencies but is limited to Gibbs sampling for inference, to the output layer of a neural network. We show that despite its simplicity, jointly learning this new architecture yields significant improvements in performance over the baseline neural network. In particular, our experimental evaluation on three video activity classification datasets: Charades, Textually Annotated Cooking Scenes (TACoS), and Wetlab, and three multi-label image classification datasets: MS-COCO, PASCAL VOC, and NUS-WIDE show that deep dependency networks are almost always superior to pure neural architectures that do not use dependency networks.


DDN Expands AI Computing Collaborations

#artificialintelligence

DALLAS, Nov. 15, 2022, SC22, Booth #2828 -- DDN, the global leader in artificial intelligence (AI) and multi-cloud data management solutions, today announced at SC22, The International Conference for High Performance Computing, Networking, Storage, and Analysis, a new Reference Architecture in collaboration with Atos. DDN also introduced enhancements to its scalable and flexible monitoring interface, DDN Insight, to streamline and simplify management and support of HPC and AI infrastructures at-scale. DDN worked in tight collaboration with Atos on this new Reference Architecture to advance DDN's goal of simplifying the adoption of advanced AI infrastructure for enterprises and research institutions. Historically, storage systems were often chosen to complement compute infrastructure as it was being deployed. This approach leads to silos of data and requires data movement to use the optimal compute platform for a certain stage of processing.


Deconvolutional Density Network: Free-Form Conditional Density Estimation

Chen, Bing, Islam, Mazharul, Wang, Lin, Gao, Jisuo, Orchard, Jeff

arXiv.org Machine Learning

Conditional density estimation is the task of estimating the probability of an event, conditioned on some inputs. A neural network can be used to compute the output distribution explicitly. For such a task, there are many ways to represent a continuous-domain distribution using the output of a neural network, but each comes with its own limitations for what distributions it can accurately render. If the family of functions is too restrictive, it will not be appropriate for many datasets. In this paper, we demonstrate the benefits of modeling free-form distributions using deconvolution. It has the advantage of being flexible, but also takes advantage of the topological smoothness offered by the deconvolution layers. We compare our method to a number of other density-estimation approaches, and show that our Deconvolutional Density Network (DDN) outperforms the competing methods on many artificial and real tasks, without committing to a restrictive parametric model.


Exxact Partners With DDN to Integrate Storage Solutions for AI and HPC

#artificialintelligence

Exxact Corporation, a leading provider of high performance computing (HPC), artificial intelligence (AI), and data center solutions, announced the expansion of its portfolio of high-end storage with offerings from DDN, the global leader in AI and multi cloud data management. Exxact is partnering with DDN to meet the ever-increasing requirements of today's enterprise, where end-users can greatly benefit by adopting DDN's best-of-breed high-performance storage solutions for end-to-end data management, from data creation and persistent storage to active archives and the cloud. "By partnering with DDN, a leading big data storage supplier, we are able to offer our customers high-end, fully integrated HPC & AI solutions, and DDN is a perfect fit for this," said Jason Chen, Vice President at Exxact Corporation. "DDN Storage offers extreme performance for AI and HPC applications requiring only a small amount of rack space." "We are honored to partner with Exxact to de-risk data center solution investments and provide our joint expertise for customers looking to benefit from intelligent infrastructure. This collaboration will allow us to bring enterprise ready solutions to organizations who are ready to enable AI for production and deliver faster time to insight," said Kurt Kuckein, vice president of marketing, DDN.