With the growing demand for decentralized collaborative analysis of privacy-sensitive data, federated multi-view clustering (FMVC) has attracted widespread attention due to its ability to balance privacy protection and collaborative modeling. However, current methods still face the following challenges: (1) Clients need to frequently upload high-dimensional data such as model parameters or graph structures, resulting in high communication costs; (2) The structured data uploaded often contains semantic features and has a high risk of being inverted; (3) The server usually merges the data from all clients with the fixed fusion rule, which may result in a suboptimized clustering result when there exist low-quality clients. To address the issues, we propose a new trusted federated multi-view clustering framework (EvoFMVC) that introduces three key innovations: First, lightweight trusted evidence serves as a compact communication medium, significantly reducing overhead compared to conventional model parameters or graph structures. Second, trusted evidences express clustering results in the form of probability distribution, which avoids the risk of structured information being easily inverted. Lastly, we formalize the server-side aggregation process as a neural architecture search (NAS) task where the server flexibly uses different fusion operators to filter and fuse necessary views through evolutionary algorithms, which significantly improves the fusion effect and model performance. Experimental results on multiple datasets show that our method is superior to existing FMVC methods in terms of clustering accuracy and communication efficiency.

Multi-view classification based on the Dempster-Shafer theory is widely recognized for its reliability in safety-critical domains with multi-view data. However, the adoption of a late fusion strategy constrains information interaction among views, thereby leading to suboptimal utilization of multi-view data. A recent advancement addressing this limitation involves generating a pseudo view by concatenating individual views. Yet, the efficacy of this pseudo view may diminish when incorporating underperforming views like noisy views. Additionally, the integration of a pseudo view exacerbates the issue of imbalanced multi-view learning, as it contains a disproportionate amount of information compared to individual views. To address these issues, we propose the enhancing Trusted multi-view classification via Evolutionary multi-view Fusion (TEF) approach. TEF employs an evolutionary multi-view architecture search method to create a high-quality fusion architecture serving as the pseudo view, facilitating adaptive view and fusion operator selection. Furthermore, TEF enhances each view within the fusion architecture by concatenating the fusion architecture's decision output with its respective view. Our experimental results demonstrate the effectiveness of this straightforward yet powerful strategy in mitigating imbalanced multi-view learning issues, particularly on complex many-view datasets exceeding three views. Extensive evaluations across 13 multi-view datasets validate the superior performance of our proposed method compared to other trusted multi-view learning approaches. The code is available at https://github.com/fupinhan123/TEF.

Multi-modal neural architecture search (MNAS) is an effective approach to obtain task-adaptive multi-modal classification models. Deep neural networks, as currently main-stream feature extractors, can provide hierarchical features for each modality. Existing MNAS methods face difficulty in exploiting such hierarchical features due to their different form coexistence such as tensorial multi-scale features and vectorized penultimate features. Moreover, existing methods always focus on the evolution of fusion operators or vectorized features of all modalities, constraining search space. In this paper, a novel two-stage method called multi-modal multi-scale evolutionary neural architecture search (MM-ENAS) is proposed. The first stage unifies the representation form of hierarchical features by the proposed evolutionary statistics strategy. The second stage identifies the optimal combination of basic fusion operations for all unified hierarchical features by the evolutionary algorithm. MM-ENAS increases search space by simultaneously searching for feature statistical extraction methods, basic fusion operators and feature representation set consisting of tensorial multi-scale features and vectorized penultimate features. Experimental results on three multi-modal tasks demonstrate that the proposed method achieves competitive performance in terms of accuracy, search time, and number of parameters compared to existing representative MNAS methods. Additionally, the method exhibits fast adaptation to various multi-modal tasks.

Neural architecture search-based multi-modal classification (NAS-MMC) methods can individually obtain the optimal classifier for different multi-modal data sets in an automatic manner. However, most existing NAS-MMC methods are dramatically time consuming due to the requirement for training and evaluating enormous models. In this paper, we propose an efficient evolutionary-based NAS-MMC method called divide-and-conquer neural architecture search (DC-NAS). Specifically, the evolved population is first divided into k+1 sub-populations, and then k sub-populations of them evolve on k small-scale data sets respectively that are obtained by splitting the entire data set using the k-fold stratified sampling technique; the remaining one evolves on the entire data set. To solve the sub-optimal fusion model problem caused by the training strategy of partial data, two kinds of sub-populations that are trained using partial data and entire data exchange the learned knowledge via two special knowledge bases. With the two techniques mentioned above, DC-NAS achieves the training time reduction and classification performance improvement. Experimental results show that DC-NAS achieves the state-of-the-art results in term of classification performance, training efficiency and the number of model parameters than the compared NAS-MMC methods on three popular multi-modal tasks including multi-label movie genre classification, action recognition with RGB and body joints and dynamic hand gesture recognition.

Most existing NAS-based multi-modal classification (MMC-NAS) methods are optimized using the classification accuracy.They can not simultaneously provide multiple models with diverse perferences such as model complex and classification performance for meeting different users' demands. Combining NAS-MMC with multi-objective optimization is a nature way for this issue. However, the challenge problem of this solution is the high computation cost. For multi-objective optimization, the computing bottleneck is pareto front search. Some higher-quality MMC models (namely core structures, CSs) consisting of high-quality features and fusion operators are easier to identify. We find that CSs have a close relation with the pareto front (PF), i.e., the individuals lying in PF contain the CSs. Based on the finding, we propose an efficient multi-objective neural architecture search for multi-modal classification by applying CSs to guide the PF search (CoMO-NAS). In conclusion, experimental results thoroughly demonstrate the effectiveness of our CoMO-NAS. Compared to state-of-the-art competitors on benchmark multi-modal tasks, we achieve comparable performance with lower model complexity in shorter search time.