Existing federated clustering methods typically assume that either all clients supply the same type of single-modal/multi-modal data, or that different clients provide various modalities describing the same object. However, a prevalent real-world scenario involves clients contributing data from diverse and unrelated modalities. Addressing the challenge of uncovering clustering patterns from such heterogeneous modality data distributed across distinct clients is crucial. In this paper, we propose a novel cross-modal feature decoupling-based mixed federated clustering model. To address client heterogeneity, we introduce a cross-modal feature decoupling module for each client, designed to decouple modality-agnostic and modality-specific features through distinct encoders.Only the modality-agnostic encoder parameters and clustering centers of each client are transmitted to the server. This enables the server to aggregate various modality-agnostic encoders, effectively discovering the global clustering structure while avoiding interference from modality-specific noise. Moreover, we develop a global consistent complementary clustering module to integrate the complementary clustering centers from various clients. The global clustering centers are then dispatched back to clients to guide and calibrate their local clustering models. Experimental results on three public datasets show the superiority of the proposed model compared to classic federated clustering methods.

Multivariate Time Series Classification (MTSC) has important research significance and practical value. Deep learning models have achieved considerable success in addressing MTSC problems. However, a key challenge faced by existing classification models is how to effectively consider the correlations between time series instances and across channels simultaneously, as well as how to capture the dynamic of these inter-channel correlations over time. Current methods often fall short in these aspects: on one hand, they fail to fully account for the combined effects of inter-instance and inter-channel correlations; on the other hand, they largely overlook the dynamic nature of how inter-channel correlations change over time. To address these issues, we propose a novel graph neural network model, called Similarity-Aware Graph of Graphs neural networks (SAGoG), for multivariate time series classification. This model can comprehensively consider the dependencies between channel-level and instance-level time series, it dynamically learns dependency features through graph structure evolution and graph pooling layers. We conduct experiments on the UEA dataset to validate the SAGoG model, and the results demonstrate its outstanding performance in multivariate time series classification tasks.

Long Document Classification (LDC) has attracted great attention in Natural Language Processing and achieved considerable progress owing to the large-scale pre-trained language models. In spite of this, as a different problem from the traditional text classification, LDC is far from being settled. Long documents, such as news and articles, generally have more than thousands of words with complex structures. Moreover, compared with flat text, long documents usually contain multi-modal content of images, which provide rich information but not yet being utilized for classification. In this article, we propose a novel cross-modal method for long document classification, in which multiple granularity feature shifting networks are proposed to integrate the multi-scale text and visual features of long documents adaptively. Additionally, a multi-modal collaborative pooling block is proposed to eliminate redundant fine-grained text features and simultaneously reduce the computational complexity. To verify the effectiveness of the proposed model, we conduct experiments on the Food101 dataset and two constructed multi-modal long document datasets. The experimental results show that the proposed cross-modal method outperforms the single-modal text methods and defeats the state-of-the-art related multi-modal baselines.

In recent years, Graph Neural Networks (GNNs) have achieved unprecedented success in handling graph-structured data, thereby driving the development of numerous GNN-oriented techniques for inductive knowledge graph completion (KGC). A key limitation of existing methods, however, is their dependence on pre-defined aggregation functions, which lack the adaptability to diverse data, resulting in suboptimal performance on established benchmarks. Another challenge arises from the exponential increase in irrelated entities as the reasoning path lengthens, introducing unwarranted noise and consequently diminishing the model’s generalization capabilities. To surmount these obstacles, we design an innovative framework that synergizes M ulti- L evel S ampling with an A daptive A ggregation mechanism (MLSAA). Distinctively, our model couples GNNs with enhanced set transformers, enabling dynamic selection of the most appropriate aggregation function tailored to specific datasets and tasks. This adaptability significantly boosts both the model’s flexibility and its expressive capacity. Additionally, we unveil a unique sampling strategy designed to selectively filter irrelevant entities, while retaining potentially beneficial targets throughout the reasoning process. We undertake an exhaustive evaluation of our novel inductive KGC method across three pivotal benchmark datasets and the experimental results corroborate the efficacy of MLSAA.

The goal of mixed-modality clustering, which differs from typical multi-modality/view clustering, is to divide samples derived from various modalities into several clusters. This task has to solve two critical semantic gap problems: i) how to generate the missing modalities without the pairwise-modality data; and ii) how to align the representations of heterogeneous modalities. To tackle the above problems, this paper proposes a novel mixedmodality clustering model, which integrates the missing-modality generation and the heterogeneous modality alignment into a unified framework. During the missing-modality generation process, a bidirectional mapping is established between different modalities, enabling generation of preliminary representations for the missing-modality using information from another modality. Then the intra-modality bipartite graphs are constructed to help generate better missing-modality representations by weighted aggregating existing intra-modality neighbors. In this way, a pairwise-modality representation for each sample can be obtained. In the process of heterogeneous modality alignment, each modality is modelled as a graph to capture the global structure among intra-modality samples and is aligned against the heterogeneous modality representations through the adaptive heterogeneous graph matching module. Experimental results on three public datasets show the effectiveness of the proposed model compared to multiple state-of-the-art multi-modality/view clustering methods.

Knowledge Graph Completion (KGC) aims at inferring missing entities or relations by embedding them in a low-dimensional space. However, most existing KGC methods generally fail to handle the complex concepts hidden in triplets, so the learned embeddings of entities or relations may deviate from the true situation. In this article, we propose a novel M ulti- c oncept R epresentation L earning (McRL) method for the KGC task, which mainly consists of a multi-concept representation module, a deep residual attention module, and an interaction embedding module. Specifically, instead of the single-feature representation, the multi-concept representation module projects each entity or relation to multiple vectors to capture the complex conceptual information hidden in them. The deep residual attention module simultaneously explores the inter- and intra-connection between entities and relations to enhance the entity and relation embeddings corresponding to the current contextual situation. Moreover, the interaction embedding module further weakens the noise and ambiguity to obtain the optimal and robust embeddings. We conduct the link prediction experiment to evaluate the proposed method on several standard datasets, and experimental results show that the proposed method outperforms existing state-of-the-art KGC methods.

With the powerful learning ability of deep convolutional networks, deep clustering methods can extract the most discriminative information from individual data and produce more satisfactory clustering results. However, existing deep clustering methods usually ignore the relationship between the data. Fortunately, the graph convolutional network can handle such relationships, opening a new research direction for deep clustering. In this paper, we propose a cross-attention based deep clustering framework, named Cross-Attention Fusion based Enhanced Graph Convolutional Network (CaEGCN), which contains four main modules: the cross-attention fusion module which innovatively concatenates the Content Auto-encoder module (CAE) relating to the individual data and Graph Convolutional Auto-encoder module (GAE) relating to the relationship between the data in a layer-by-layer manner, and the self-supervised model that highlights the discriminative information for clustering tasks. While the cross-attention fusion module fuses two kinds of heterogeneous representation, the CAE module supplements the content information for the GAE module, which avoids the over-smoothing problem of GCN. In the GAE module, two novel loss functions are proposed that reconstruct the content and relationship between the data, respectively. Finally, the self-supervised module constrains the distributions of the middle layer representations of CAE and GAE to be consistent. Experimental results on different types of datasets prove the superiority and robustness of the proposed CaEGCN.

Conventional Knowledge Graph Completion (KGC) methods typically map entities and relations to a unified space through the shared mapping matrix, and then interact with entities and relations to infer the missing items in the knowledge graph. Although this shared mapping matrix considers the suitability of all triplets, it neglects the specificity of each triplet. To solve this problem, we dynamically learn one information distributor for each triplet to exchange its specific information. In this paper, we propose a novel Triplet Distributor Network (TDN) for the knowledge graph completion task. Specifically, we adaptively learn one Triplet Distributor (TD) for each triplet to assist the interaction between the entity and relation. Furthermore, on the basis of TD, we creatively design the information exchange layer to dynamically propagate the information of the entity and relation, thus mutually enhancing entity and relation representations. Except for several commonly-used knowledge graph datasets, we still implement the link prediction task on the social-relational and medical datasets to test the proposed method. Experimental results demonstrate that the proposed method performs better than existing state-of-the-art KGC methods. The source codes of this paper are available athttps://github.com/TDNfor Knowledge Graph Completion.git.

Clustering is a fundamental and hot issue in the unsupervised learning area. With the rapid development of deep learning and graph neural networks (GNNs) techniques, researchers have proposed a series of effective clustering methods. However, most existing approaches adopt a conventional graph to aggregate the neighborhood information, where only the pairwise relations are considered. Moreover, the redundancy/noise in the raw data samples may result in less accurate sample relations and inferior clustering results. In this paper, we proposed a new GNNs based clustering method, which adopts the hypergraph learning approach to explore the high-order relationship for accurate relation learning. Specifically, we first construct two hypergraph representations based on the topology feature and attribute feature from data samples. Then, a self-supervised structure is integrated to learn a cross-correlation matrix from the original hypergraph to act as a higher-order neighborhood with reduced redundancy and noise. Finally the embedding representation of the clustering space is learned in the graph convolution. The proposed method has been evaluated on six public datasets for clustering tasks. Experimental results show that our proposed method outperforms the state-of-the-art ones.

Locality preserving projection (LPP) is a dimensionality reduction algorithm preserving the neighhorhood graph structure of data. However, the conventional LPP is sensitive to outliers existing in data. This article proposes a novel low-rank LPP model called LR-LPP. In this new model, original data are decomposed into the clean intrinsic component and noise component. Then the projective matrix is learned based on the clean intrinsic component which is encoded in low-rank features. The noise component is constrained by theℓ1-norm which is more robust to outliers. Finally, LR-LPP model is extended to LR-FLPP in which low-dimensional feature is measured by F-norm. LR-FLPP will reduce aggregated error and weaken the effect of outliers, which will make the proposed LR-FLPP even more robust for outliers. The experimental results on public image databases demonstrate the effectiveness of the proposed LR-LPP and LR-FLPP.

Linear discriminant analysis (LDA) is a well-known supervised method for dimensionality reduction in which the global structure of data can be preserved. The classical LDA is sensitive to the noises, and the projection direction of LDA cannot preserve the main energy. This article proposes a novel feature extraction model with l 2,1 norm constraint based on LDA, termed as RALDA. This model preserves within-class local structure in the latent subspace according to the label information. To reduce information loss, it learns a projection matrix and an inverse projection matrix simultaneously. By introducing an implicit variable and matrix norm transformation, the alternating direction multiple method with updating variables is designed to solve the RALDA model. Moreover, both computational complexity and weak convergence property of the proposed algorithm are investigated. The experimental results on several public databases have demonstrated the effectiveness of our proposed method.

Dimensionality reduction is widely used to deal with high-dimensional data. As a famous dimensionality reduction method, principal component analysis (PCA) aiming at finding the low dimension feature of original data has made great successes, and many improved PCA algorithms have been proposed. However, most algorithms based on PCA only consider the linear correlation of data features. In this article, we propose a novel dimensionality reduction model called maximally correlated PCA based on deep parameterization learning (MCPCADP), which takes nonlinear correlation into account in the deep parameterization framework for the purpose of dimensionality reduction. The new model explores nonlinear correlation by maximizing Ky-Fan norm of the covariance matrix of nonlinearly mapped data features. A new BP algorithm for model optimization is derived. In order to assess the proposed method, we conduct experiments on both a synthetic database and several real-world databases. The experimental results demonstrate that the proposed algorithm is comparable to several widely used algorithms.

Clustering is one of the fundamental topics in data mining and pattern recognition. As a prospective clustering method, the subspace clustering has made considerable progress in recent researches, e.g., sparse subspace clustering (SSC) and low rank representation (LRR). However, most existing subspace clustering algorithms are designed for vectorial data from linear spaces, thus not suitable for high-dimensional data with intrinsic non-linear manifold structure. For high-dimensional or manifold data, few research pays attention to clustering problems. The purpose of clustering on manifolds tends to cluster manifold-valued data into several groups according to the mainfold-based similarity metric. This article proposes an extended LRR model for manifold-valued Grassmann data that incorporates prior knowledge by minimizing partial sum of singular values instead of the nuclear norm, namely Partial Sum minimization of Singular Values Representation (GPSSVR). The new model not only enforces the global structure of data in low rank, but also retains important information by minimizing only smaller singular values. To further maintain the local structures among Grassmann points, we also integrate the Laplacian penalty with GPSSVR. The proposed model and algorithms are assessed on a public human face dataset, some widely used human action video datasets and a real scenery dataset. The experimental results show that the proposed methods obviously outperform other state-of-the-art methods.

A new facial feature extraction method is proposed. Based on linear combination model, the method locates feature points in facial images precisely. The model uses the knowledge of prototypic faces to interpret novel faces. To get the knowledge, the prototypes are labeled manually on the feature points. Generally, the construction of the linear combination model depends on pixel-wise alignments of prototypes, and the alignments are computed by an optical flow algorithm or bootstrapping algorithm which is a full-scale optimization and not includes local information such as facial feature points. To combine local facial feature with the linear combination model, a restrained optical flow algorithm is proposed to compute the pixel-wise alignments. With the information of labeled feature points, the model matches the input facial images and extracts the feature points automatically. Implementing the feature extraction method on the MPI face database, the experimental results show that the method has good performance.