Reviewerly/exHarmony huggingface dataset:
SVQ-ACT: Querying for Actions over Videos

We present SVQ-ACT, a system capable of evaluating declarative action and object queries over input videos. Our approach is independent of the underlying object and action detection models utilized. Users may issue queries involving action and specific objects (e.g., a human riding a bicycle, close to a traffic light and a car left of the bicycle) and identify video clips that satisfy query constraints. Our system is capable of operating in two main settings, namely online and offline. In the online setting, the user specifies a video source (e.g., a surveillance video) and a declarative query containing an action and object predicates. Our system will identify and label in real-time all frame sequences that match the query. In the offline mode, the system accepts a video repository as input, preprocesses all the video in an offline manner and extracts suitable metadata. Following this step, users can execute any query they wish interactively on the video repository (containing actions and objects supported by the underlying detection models) to identify sequences of frames from videos that satisfy the query. In this case, to limit the number of results produced, we introduce novel result ranking algorithms that can produce the k most relevant results efficiently.We demonstrate that SVQ-ACT can correctly capture the desired query semantics and execute queries efficiently and correctly, delivering a high degree of accuracy.
Reinforcement Learning Enhanced Weighted Sampling for Accurate Subgraph Counting on Fully Dynamic Graph Streams

As the popularity of graph data increases, there is a growing need to count the occurrences of subgraph patterns of interest, for a variety of applications. Many graphs are massive in scale and also fully dynamic (with insertions and deletions of edges), rendering exact computation of these counts to be infeasible. Common practice is, instead, to use a small set of edges as a sample to estimate the counts. Existing sampling algorithms for fully dynamic graphs sample the edges with uniform probability. In this paper, we show that we can do much better if we sample edges based on their individual properties. Specifically, we propose a weighted sampling algorithm called WSD for estimating the subgraph count in a fully dynamic graph stream, which samples the edges based on their weights that indicate their importance and reflect their properties. We determine the weights of edges in a data-driven fashion, using a novel method based on reinforcement learning. We conduct extensive experiments to verify that our technique can produce estimates with smaller errors while often running faster compared with existing algorithms.
DBCatcher: A Cloud Database Online Anomaly Detection System based on Indicator Correlation

Anomaly detection system plays an important role in maintaining the stability of cloud database. Existing studies mainly focus on significant deviations in multivariate time series, such as a combination of CPU utilization, transactions per second, etc, to detect abnormal issues. Due to the complexity of cloud database structure and functions, these approaches are difficult to achieve a balance among detection performance, detection efficiency and workload adaptability. In this paper, we propose DBCatcher, a cloud database online anomaly detection system based on indicator correlation. Through extensive analysis of real-world cloud database time series, we find the correlations among trends in the same key performance indicators across databases within the same unit, which inspires us to explore a time series correlation measurement method that can efficiently detect abnormal issues. Meanwhile, we design a flexible time window observation mechanism and an adaptive threshold learning policy to minimize misjudgment caused by key performance indicator fluctuations, greatly enhancing the detection performance and workload adaptability. We conduct extensive experiments under real-world and synthetic workloads. Experimental results show that DBCatcher significantly improves the detection performance and detection efficiency compared to existing methods.
Automatic Fusion Network for Cold-start CVR Prediction with Explicit Multi-Level Representation

Estimating conversion rate (CVR) accurately has been one of the most central problems in online advertising. Existing methods in production focus on learning effective interactions among features to boost the model performance. Despite great success, these methods treat all the features equally without distinction. However, different features suffer differently from cold-start issues. Tail elements in those high-cardinality features, which we denote as fine-grained features, tend to have inadequate samples and thus fail to obtain semantically meaningful embeddings. Interacting with those features leads astray and impairs the accuracy of new ads in a cold-start scenario. In this paper, we propose Automatic Fusion Network (AutoFuse) to better tackle the challenge. AutoFuse explicitly separates features into groups based on their granularity and learns multiple levels of representation conditioned on different combinations of feature groups. Concretely, AutoFuse learns an ad-level representation to depict the unique individual character and a group-level representation to portray the collective information by discarding the fine-grained features. The final robust and general ad representation is obtained by integrating these two level representations adaptively. Such a combination encompasses a wider amount of information, and thereby mitigates the cold-start issue. Extensive experiments on two industrial-scale datasets and three public datasets show that AutoFuse significantly and consistently outperforms a spectrum of competitive methods including our currently deployed model. Meanwhile, the remarkable improvement on new ads validates the effectiveness of our method in cold-start scenarios. We design AutoFuse as a generic approach and thus it can be seamlessly transferred into other domains. Our method has been deployed online to serve billions of users and ads and has achieved significant GMV gain of 2.84%.
LightTraffic: On Optimizing CPU-GPU Data Traffic for Efficient Large-scale Random Walks

As a fundamental tool for graph analysis, random walk receives extensive attention in both industry and academia. For computing massive random walks, recent works show that GPUs provide a good option to accelerate the performance. However, due to the limited memory space of modern GPUs, it is infeasible to have both the graph data and walk index fully reside in GPU memory when running large-scale random walks. Thus, it necessitates an out-of-GPU-memory design, but this inevitably induces large amounts of CPU-GPU data transmission traffic and thus hinders the overall performance. In this paper, we develop LightTraffic, which optimizes the data transmission between CPU and GPU memory under the constraint of GPU memory capacity with various system designs, including a memory-efficient scheme for partition-based management and multiple scheduling techniques. LightTraffic is a fully out-of-GPU-memory design, so it supports running large-scale random walks on GPUs. Experiments on our prototype show that LightTraffic outperforms various state-of-the-art CPU-based in-memory systems which also support large-scale random walks. For example, compared to the CPU-based systems FlashMob and ThunderRW, which are highly optimized for random walks, LightTraffic achieves 1.7−5.0× and 1.4 − 12.8× performance speedup, respectively. It also achieves up to an order of magnitude speedup when compared to the GPU-based system Subway which also supports large-scale random walks with an out-of-GPU-memory design for graph data.
Efficient Regular Expression Matching Based on Positional Inverted Index : (Extended Abstract)

We study the efficient regular expression (regex) matching problem. Existing algorithms are scanning-based algorithms that typically use an equivalent automaton compiled from the regex query to verify a document. Although some works propose various strategies to quickly jump to candidate locations in a document where a query result may appear, they still need to utilize the scanning-based method to verify these candidate locations. These methods become inefficient when there are still many candidate locations needed to be verified. In this paper, we propose a novel approach to efficiently compute all matching positions for a regex query purely based on a positional q-gram inverted index. We propose a gram-driven NFA to represent the language of a regex and show all regex matching locations can be obtained by finding positions on q-grams of GNFA that satisfy certain positional constraints. Then we propose several GNFA-based query plans to answer the query using the positional inverted index. In order to improve the query efficiency, we design the algorithm to build a tree-based query plan by carefully choosing a checking order for positional constraints. Experimental results on real-world datasets show that our method outperforms state-of-the-art methods by up to an order of magnitude in query efficiency.
SEIGN: A Simple and Efficient Graph Neural Network for Large Dynamic Graphs

Graph neural networks (GNNs) have accomplished great success in learning complex systems of relations arising in broad problem settings ranging from e-commerce, social networks to data management. Training GNNs over large-scale graphs poses challenges for constrained compute resources due to the heavy data dependencies between the nodes. Moreover, modern relational data is constantly evolving, which creates an additional layer of learning challenges with respect to the model scalability and expressivity. This paper introduces a simple and efficient learning algorithm for large discrete-time dynamic graphs (DTDGs) – a widely adopted data model for many applications. We particularly tackle two critical challenges: (1) how the model can be efficiently trained on large-scale DTDGs to exploit hardware accelerators with small memory footprint, and (2) how the model can effectively capture the changing dynamics of the graphs. To the best of our knowledge, existing GNNs fail to address both challenges in their models. Hence, we propose a scalable evolving inception GNN, called SEIGN. Specifically, SEIGN features two connected evolving components that adapt the graph model to the arriving snapshot and capture the changing dynamics of the node embeddings, respectively. To scale up the model training, SEIGN introduces a parameter-free message passing step for DTDGs to substantially remove the data dependencies in training. Furthermore, it significantly reduces the training memory footprint and allows us to construct a succinct graph mini-batch without performing neighborhood sampling. We further optimize the proposed evolving strategies by extracting features from neighbors at varying scales to increase the expressive power of the node representations. Our experimental evaluation, on both public benchmark and real industrial datasets, demonstrates that SEIGN achieves 2%–20% improvement in Area Under Curve (AUC) and Average Precision (AP) on the prediction task over the state-of-the-art baselines. SEIGN also supports efficient graph mini-batch training and gains 2–16 times speedup in epoch computation time over the entire DTDGs.
Group Buying Recommendation Model Based on Multi-task Learning

In recent years, group buying has become one popular kind of online shopping activities, thanks to its larger sales and lower unit price. Unfortunately, seldom research focuses on the recommendations specifically for group buying by now. Although some recommendation models have been proposed for group recommendation, they can not be directly used to achieve the real-world group buying recommendation, due to the essential difference between group recommendation and group buying recommendation. In this paper, we first formalize the task of group buying recommendation into two sub-tasks. Then, based on our insights into the correlations and interactions between the two sub-tasks, we propose a novel recommendation model for group buying, namely MGBR, which is built mainly with a multi-task learning module. To improve recommendation performance further, we devise some collaborative expert networks and adjusted gates in the multi-task learning module, to promote the information interaction between the two sub-tasks. Furthermore, we propose two auxiliary losses corresponding to the two sub-tasks, to refine the representation learning in our model. Our extensive experiments not only demonstrate that the augmented representations learned in our model result in better performance than previous recommendation models, but also justify the impacts of the specially designed components in our model. To reproduce our model’s recommendation results conveniently, we have provided our model’s source code and dataset on https://github.com/DeqingYang/MGBR.
Incremental Learning for Multi-Interest Sequential Recommendation

In recent years, sequential recommendation has been widely researched, which aims to predict the next item of interest based on user’s previously interacted item sequence. Existing works utilize capsule network and self-attention method to explicitly capture multiple underlying interests from a user’s interaction sequence, achieving the state-of-the-art sequential recommendation performance. In practice, the lengths of user interaction sequences are ever-increasing and users might develop new interests from new interactions, and a model should be updated or even expanded continuously to capture the new user interests. We refer to this problem as incremental multi-interest sequential recommendation, which has not yet been well investigated in the existing literature. In this paper, we propose an effective incremental learning framework for multi-interest sequential recommendation called IMSR, which augments the traditional fine-tuning strategy with the existing-interests retainer (EIR), new-interests detector (NID), and projection-based interests trimmer (PIT) to adaptively expand the model to accommodate user’s new interests and prevent it from forgetting user’s existing interests. Extensive experiments on real-world datasets verify the effectiveness of the proposed IMSR on incremental multi-interest sequential recommendation, compared with various baseline approaches.
Stable Tuple Embeddings for Dynamic Databases

We study the problem of computing an embedding of the tuples of a relational database in a manner that is extensible to dynamic changes of the database. In this problem, the embedding should be stable in the sense that it should not change on the existing tuples due to the embedding of newly inserted tuples (as database applications might already rely on existing embeddings); at the same time, the embedding of all tuples, old and new, should retain high quality. This task is challenging since inter-dependencies among the embeddings of different entities are inherent in state-of-the-art embedding techniques for structured data.We study two approaches to solving the problem. The first is an adaptation of Node2Vec to dynamic databases. The second is the FoRWaRD algorithm (Foreign Key Random Walk Embeddings for Relational Databases) that draws from embedding techniques for general graphs and knowledge graphs, and is inherently utilizing the schema and its key and foreign-key constraints. We evaluate the embedding algorithms using a collection of downstream tasks of column prediction over geographical and biological domains. We find that in the traditional static setting, our two embedding methods achieve comparable results that are compatible with the state-of-the-art for the specific applications. In the dynamic setting, we find that the FoRWaRD algorithm generally outperforms and runs faster than the alternatives, and moreover, it features only a mild reduction of quality even when the database consists of more than half newly inserted tuples after the initial training of the embedding.
GAMMA: A Graph Pattern Mining Framework for Large Graphs on GPU

Graph pattern mining (GPM) is getting increasingly important recently. There are many parallel frameworks for GPM, many of which suffer from performance. GPU is a powerful option for graph processing, which has excellent potential for performance improvement; however, parallel GPM algorithms produce a large number of intermediate results, limiting GPM implementations on GPU.In this paper, we present GAMMA, an out-of-core GPM framework on GPU, and it makes full use of host memory to process large graphs. Specifically, GAMMA adopts a self-adaptive implicit host memory access manner to achieve high bandwidth, which is transparent to users. GAMMA provides flexible and effective interfaces for users to build their algorithms. We also propose several optimizations over primitives provided by GAMMA in the out-of-core GPU system. Experimental results show that GAMMA has scalability advantages in graph size over the state-of-the-art by an order of magnitude, and is also faster than existing GPM systems.
Towards Higher-order Topological Consistency for Unsupervised Network Alignment

Network alignment task, which aims to identify corresponding nodes in different networks, is of great significance for many subsequent applications. Without the need for labeled anchor links, unsupervised alignment methods have been attracting more and more attention. However, the topological consistency assumptions defined by existing methods are generally low-order and less accurate because only the edge-indiscriminative topological pattern is considered, which is especially risky in an unsupervised setting. To reposition the focus of the alignment process from low-order to higher-order topological consistency, in this paper, we propose a fully unsupervised network alignment framework named HTC. The proposed higher-order topological consistency is formulated based on edge orbits, which is merged into the information aggregation process of a graph convolutional network so that the alignment consistencies are transformed into the similarity of node embeddings. Furthermore, the encoder is trained to be multi-orbit-aware and then is refined to identify more trusted anchor links. Node correspondence is comprehensively evaluated by integrating all different orders of consistency. In addition to sound theoretical analysis, the superiority of the proposed method is also empirically demonstrated through extensive experimental evaluation. On three pairs of real-world datasets and two pairs of synthetic datasets, our HTC consistently outperforms a wide variety of unsupervised and supervised methods with the least or comparable time consumption. It also exhibits robustness to structural noise as a result of our multiorbit-aware training mechanism.
A Stitch in Time Saves Nine: Enabling Early Anomaly Detection with Correlation Analysis

Early detection of anomalies from sensor-based Multivariate Time Series (MTS) is vital for timely response to the signs of operation failures and errors. While many interesting works have been done toward solving this problem, existing methods typically detect such anomalies as outliers by making certain assumptions that allow efficient and easily understandable solutions to be used but might not be applicable to time series. Meanwhile, unsupervised deep learning-based methods might be highly accurate but often lead to challenges for real-time industrial scenarios, e.g., requiring a large amount of training data and producing unstable output.In this paper, we propose a new approach, CAD, to detect anomalies from sensor-based MTS. We aim to leverage the latent correlations between sensors by first converting the MTS into a sequence of Time-Series Graphs (TSGs) that connect sensors to their highly correlated neighbors within a certain time period. Then, we track the unusual correlation variations between sensors on the sequence of TSGs. By analyzing the correlation variations with a theoretical guarantee, CAD can detect the time of occurrence for the anomalies simultaneously with the sensors that are affected as early as possible.Extensive experiments over eight real-world datasets show that CAD is effective, scalable, yet stable compared to nine state-of-the-art methods while keeping comparable efficiency. Moreover, it maintains above 85% accuracy on large-scale datasets with over 1,000 sensors. Notably, CAD can determine relevant sensors in a very early stage of the anomaly so that timely predictive maintenance can be done. The code is available at https://github.com/YihaoAng/CAD.
Unsupervised Graph Outlier Detection: Problem Revisit, New Insight, and Superior Method

A large number of studies on Graph Outlier Detection (GOD) have emerged in recent years due to its wide applications, in which Unsupervised Node Outlier Detection (UNOD) on attributed networks is an important area. UNOD focuses on detecting two kinds of typical outliers in graphs: the structural outlier and the contextual outlier. Most existing works conduct experiments based on datasets with injected outliers. However, we find that the most widely-used outlier injection approach has a serious data leakage issue. By only utilizing such data leakage, a simple approach can achieve state-of-the-art performance in detecting outliers. In addition, we observe that existing algorithms have a performance drop with the mitigated data leakage issue. The other major issue is on balanced detection performance between the two types of outliers, which has not been considered by existing studies.In this paper, we analyze the cause of the data leakage issue in depth since the injection approach is a building block to advance UNOD. Moreover, we devise a novel variance-based model to detect structural outliers, which outperforms existing algorithms significantly and is more robust at kinds of injection settings. On top of this, we propose a new framework, Variance-based Graph Outlier Detection (VGOD), which combines our variance-based model and attribute reconstruction model to detect outliers in a balanced way. Finally, we conduct extensive experiments to demonstrate the effectiveness and efficiency of VGOD. The results on 5 real-world datasets validate that VGOD achieves not only the best performance in detecting outliers but also a balanced detection performance between structural and contextual outliers.