158 research outputs found
Intent Contrastive Learning with Cross Subsequences for Sequential Recommendation
The user purchase behaviors are mainly influenced by their intentions (e.g.,
buying clothes for decoration, buying brushes for painting, etc.). Modeling a
user's latent intention can significantly improve the performance of
recommendations. Previous works model users' intentions by considering the
predefined label in auxiliary information or introducing stochastic data
augmentation to learn purposes in the latent space. However, the auxiliary
information is sparse and not always available for recommender systems, and
introducing stochastic data augmentation may introduce noise and thus change
the intentions hidden in the sequence. Therefore, leveraging user intentions
for sequential recommendation (SR) can be challenging because they are
frequently varied and unobserved. In this paper, Intent contrastive learning
with Cross Subsequences for sequential Recommendation (ICSRec) is proposed to
model users' latent intentions. Specifically, ICSRec first segments a user's
sequential behaviors into multiple subsequences by using a dynamic sliding
operation and takes these subsequences into the encoder to generate the
representations for the user's intentions. To tackle the problem of no explicit
labels for purposes, ICSRec assumes different subsequences with the same target
item may represent the same intention and proposes a coarse-grain intent
contrastive learning to push these subsequences closer. Then, fine-grain intent
contrastive learning is mentioned to capture the fine-grain intentions of
subsequences in sequential behaviors. Extensive experiments conducted on four
real-world datasets demonstrate the superior performance of the proposed ICSRec
model compared with baseline methods.Comment: 10pages, 5figures, WSDM2024. arXiv admin note: text overlap with
arXiv:2304.0776
Quaternion-Based Graph Convolution Network for Recommendation
Graph Convolution Network (GCN) has been widely applied in recommender
systems for its representation learning capability on user and item embeddings.
However, GCN is vulnerable to noisy and incomplete graphs, which are common in
real world, due to its recursive message propagation mechanism. In the
literature, some work propose to remove the feature transformation during
message propagation, but making it unable to effectively capture the graph
structural features. Moreover, they model users and items in the Euclidean
space, which has been demonstrated to have high distortion when modeling
complex graphs, further degrading the capability to capture the graph
structural features and leading to sub-optimal performance. To this end, in
this paper, we propose a simple yet effective Quaternion-based Graph
Convolution Network (QGCN) recommendation model. In the proposed model, we
utilize the hyper-complex Quaternion space to learn user and item
representations and feature transformation to improve both performance and
robustness. Specifically, we first embed all users and items into the
Quaternion space. Then, we introduce the quaternion embedding propagation
layers with quaternion feature transformation to perform message propagation.
Finally, we combine the embeddings generated at each layer with the mean
pooling strategy to obtain the final embeddings for recommendation. Extensive
experiments on three public benchmark datasets demonstrate that our proposed
QGCN model outperforms baseline methods by a large margin.Comment: 13 pages, 7 figures, 6 tables. Submitted to ICDE 202
Meta-optimized Joint Generative and Contrastive Learning for Sequential Recommendation
Sequential Recommendation (SR) has received increasing attention due to its
ability to capture user dynamic preferences. Recently, Contrastive Learning
(CL) provides an effective approach for sequential recommendation by learning
invariance from different views of an input. However, most existing data or
model augmentation methods may destroy semantic sequential interaction
characteristics and often rely on the hand-crafted property of their
contrastive view-generation strategies. In this paper, we propose a
Meta-optimized Seq2Seq Generator and Contrastive Learning (Meta-SGCL) for
sequential recommendation, which applies the meta-optimized two-step training
strategy to adaptive generate contrastive views. Specifically, Meta-SGCL first
introduces a simple yet effective augmentation method called
Sequence-to-Sequence (Seq2Seq) generator, which treats the Variational
AutoEncoders (VAE) as the view generator and can constitute contrastive views
while preserving the original sequence's semantics. Next, the model employs a
meta-optimized two-step training strategy, which aims to adaptively generate
contrastive views without relying on manually designed view-generation
techniques. Finally, we evaluate our proposed method Meta-SGCL using three
public real-world datasets. Compared with the state-of-the-art methods, our
experimental results demonstrate the effectiveness of our model and the code is
available
Mixed Pattern Matching-Based Traffic Abnormal Behavior Recognition
A motion trajectory is an intuitive representation form in time-space domain for a micromotion behavior of moving target. Trajectory analysis is an important approach to recognize abnormal behaviors of moving targets. Against the complexity of vehicle trajectories, this paper first proposed a trajectory pattern learning method based on dynamic time warping (DTW) and spectral clustering. It introduced the DTW distance to measure the distances between vehicle trajectories and determined the number of clusters automatically by a spectral clustering algorithm based on the distance matrix. Then, it clusters sample data points into different clusters. After the spatial patterns and direction patterns learned from the clusters, a recognition method for detecting vehicle abnormal behaviors based on mixed pattern matching was proposed. The experimental results show that the proposed technical scheme can recognize main types of traffic abnormal behaviors effectively and has good robustness. The real-world application verified its feasibility and the validity
Unlocking the SingleāDomain Epitaxy of Halide Perovskites
The growth of epitaxial semiconductors and oxides has long since revolutionized the electronics and optics fields, and continues to be exploited to uncover new physics stemming from quantum interactions. While the recent emergence of halide perovskites offers exciting new opportunities for a range of thināfilm electronics, the principles of epitaxy have yet to be applied to this new class of materials and the full potential of these materials is still not yet known. In this work, singleādomain inorganic halide perovskite epitaxy is demonstrated. This is enabled by reactive vapor phase deposition onto single crystal metal halide substrates with congruent ionic interactions. For the archetypical halide perovskite, cesium tin bromide, two epitaxial phases, a cubic phase and tetragonal phase, are uncovered which emerge via stoichiometry control that are both stabilized with vastly differing lattice constants and accommodated via epitaxial rotation. This epitaxial growth is exploited to demonstrate multilayer 2D quantum wells of a halideāperovskite system. This work ultimately unlocks new routes to push halide perovskites to their full potential.Singleādomain halide perovskite heteroepitaxy is demonstrated and multiple epitaxial phases of archetypical halide perovskite are uncovered via stiochiometry control. The epitaxial growth is further exploited to demonstrate multilayer 2D quantum wells of a halideāperovskite system and can ultimately enable their full potential in many emerging applications.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/1/admi201701003-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/2/admi201701003_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/140019/3/admi201701003.pd
Comparing health-related quality of life of Dutch and Chinese patients with traumatic brain injury: Do cultural differences play a role?
Background: There is growing interest in health related quality of life (HRQoL) as an outcome measure in international trials. However, there might be differences in the conceptualization of HRQoL across different socio-cultural groups. The objectives of current study were: (I) to compare HRQoL, measured with the short form (SF)-36 of Dutch and Chinese traumatic brain injury (TBI) patients 1 year after injury and; (II) to assess whether differences in SF-36 profiles could be explained by cultural differences in HRQoL conceptualization. TBI patients are of particular interest because this is an important cause of diverse impairments and disabilities in functional, physical, emotional, cognitive, and social domains that may drastically reduce HRQoL. Methods: A prospective cohort study on adult TBI patients in the Netherlands (RUBICS) and a retrospective cohort study in China were used to compare HRQoL 1 year post-injury. Differences on subscales were assessed with the Mann-Whitney U-test. The internal consistency, interscale correlations, item-internal consistency and item-discriminate validity of Dutch and Chinese SF-36 profiles were examined. Confirmatory factor analysis was performed to assess whether Dutch and Chinese data fitted the SF-36 two factor-model (physical and mental construct). Results: Four hundred forty seven Dutch and 173 Chinese TBI patients were included. Dutch patients obtained significantly higher scores on role limitations due to emotional problems (p < .001) and general health (p < .001), while Chinese patients obtained significantly higher scores on physical functioning (p < .001) and bodily pain (p = .001). Scores on these subscales were not explained by cultural differences in conceptualization, since item- and scale statistics were all sufficient. However, differences among Dutch and Chinese patients were found in the conceptualization of the domains vitality, mental health and social functioning. Conclusions: One year after TBI, Dutch and Chinese patients reported a different pattern of HRQoL. Further, there might be cultural differences in the conceptualization of some of the SF-36 subscales, which has implications for outcome evaluation in multi-national trials
Refining Automatically Extracted Knowledge Bases Using Crowdsourcing
Machine-constructed knowledge bases often contain noisy and inaccurate facts. There exists significant work in developing automated algorithms for knowledge base refinement. Automated approaches improve the quality of knowledge bases but are far from perfect. In this paper, we leverage crowdsourcing to improve the quality of automatically extracted knowledge bases. As human labelling is costly, an important research challenge is how we can use limited human resources to maximize the quality improvement for a knowledge base. To address this problem, we first introduce a concept of semantic constraints that can be used to detect potential errors and do inference among candidate facts. Then, based on semantic constraints, we propose rank-based and graph-based algorithms for crowdsourced knowledge refining, which judiciously select the most beneficial candidate facts to conduct crowdsourcing and prune unnecessary questions. Our experiments show that our method improves the quality of knowledge bases significantly and outperforms state-of-the-art automatic methods under a reasonable crowdsourcing cost
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