The proliferation of generative video models has made detecting AI-generated and manipulated videos an urgent challenge. Existing detection approaches often fail to generalize across diverse manipulation types due to their reliance on isolated spatial, temporal, or spectral information, and typically require large models to perform well. This paper introduces SSTGNN, a lightweight Spatial-Spectral-Temporal Graph Neural Network framework that represents videos as structured graphs, enabling joint reasoning over spatial inconsistencies, temporal artifacts, and spectral distortions. SSTGNN incorporates learnable spectral filters and spatial-temporal differential modeling into a unified graph-based architecture, capturing subtle manipulation traces more effectively. Extensive experiments on diverse benchmark datasets demonstrate that SSTGNN not only achieves superior performance in both in-domain and cross-domain settings, but also offers strong efficiency and resource allocation. Remarkably, SSTGNN accomplishes these results with up to 42× fewer parameters than state-of-the-art models, making it highly lightweight and resource-friendly for real-world deployment.

The performance ofK-nearest neighbor (K-NN) classification depends significantly on the searched neighborhoods of test samples, namely, the neighborhood sizeKand the used distance metric. For these two issues, many methods either to acquire the adaptiveKor to learn a variant metric have been proposed and yielded appropriate performances. However, most of the existing methods ignore the fact that these two factors can be jointly learned. In this paper, we propose a Joint Evidential K-NN algorithm (JEKNN), which learns the adaptiveKof each sample and distance metric jointly based on the feedback of error function. To break the computational bottleneck of handling large datasets, a distributed version of JEKNN (JEKNN$_{\mathrm{{dis}}}$) is implemented under Apache Spark, i.e., an optimization algorithm based on distributed gradient descent and data parallelism is proposed to accelerate the training stage. Ablation and comparison experiments on small-scale datasets shows the performance improvement from the joint learning and the state-of-the-art accuracy of JEKNN, respectively. Compared to other KNN-based methods designed for Big Data, experimental results on big datasets demonstrate that JEKNN$_{\mathrm{{dis}}}$achieves better scaling efficiency without significant loss of accuracy. Besides, the generalization error bound of the proposed algorithm is also analyzed theoretically.

The EvidentialK-Nearest Neighbor (EK-NN) classification rule provides a global treatment of uncertainty and imprecision in class labels, and has been widely used in pattern recognition. Nevertheless, EK-NN still suffers from the fixed presupposition of hyper-parameterKwithout prior knowledge, due to the different spatial distribution of neighbors of each pattern in Euclidean space. More concretely, neighbors of some patterns may provide confusing information and then derive wrong classification results. To address this issue, we propose a sparse reconstructive evidentialK-NN (SEK-NN) classifier, appropriately determining an individualKfor each pattern and mapping the correlations between patterns from Euclidean space to a sparse reconstructed space. To match with this sparse reconstructed space, SEK-NN supersedes the Euclidean distance by correlation coefficients to measure the dissimilarities between patterns. When handling high-dimensional data, a parallel version of SEK-NN is implemented under the Apache Spark to speed up the parameter estimation. We respectively test SEK-NN and parallel SEK-NN over 19 middle dimensional datasets, 1 middle volume and 4 high-dimensional datasets that are up to 100 thousand of dimensions. Experimental results show that SEK-NN has great prediction performance and parallel SEK-NN is able to appropriately tackle high-dimensional datasets.

Although many algorithms have been presented to tackle the curse of dimensionality in high-dimensional clustering, most of these algorithms require prior knowledge of the number of clusters. Besides, these existing algorithms create only a hard or fuzzy partition for high-dimensional objects, which are often located in highly overlapping areas. The adoption of hard/fuzzy partition ignores the ambiguity in the assignment of objects and may lead to performance degradation. To address these issues, we propose a novel self-reconstructive evidential clustering (SREC) algorithm. After learning the correlations between objects from a self-reconstruction process, SREC provides a human-readable chart. Through this chart, users can select several objects existing in the dataset as the cluster centers, instead of just detecting the number of clusters. Under the framework of evidence theory, SREC derives a more flexible credal partition that improves the fault tolerance of clustering. Ablation study demonstrates the benefits of the self-reconstruction and evidence theory. Comparison experiments on real-world datasets show that SREC consumes competitive running time and performs better than other state-of-the-art algorithms. We also apply SREC in a real-world application scenario to illustrate the rationality of selecting cluster centers by human intervention.

The performance of$K$-nearest neighbor (K-NN) classification depends significantly on the searched neighborhoods of test samples, namely, the neighborhood size$K$and the used distance metric. For the two issues, many methods either to acquire the adaptive$K$or to learn a variant metric have been presented and yielded appropriate performance. However, most of the existing methods ignore the fact that these two factors can be jointly learned. Besides, nearly all the metric learning methods aim to shrink intra-class distance while expanding inter-class distance. In this way, embedding the learned metric directly into the K-NN does not efficiently improve its accuracy. To address these issues, we propose a joint K-NN algorithm with the help of evidence theory, optimizing the joint learning of adaptive$K$and distance matrix based on the feedback from error function. Ablation study demonstrates the performance improvement from the joint learning, and comparison experiments on real-world datasets show that our approach consumes competitive running time and achieves better performance than other state-of-the-art algorithms.