With long-tailed data and complex label hierarchy, hierarchical text classification (HTC) is a challenging multi-label text classification task. Applying prompts to pre-trained language models (PLMs) has recently become a mainstream approach in HTC. However, existing prompt-based models experience a significant drop in classification performance on tail labels. Due to the imbalanced data, HTC models still face two challenges. First, text embeddings, learned for classification, often lack distinctiveness for tail categories. Second, label embeddings suffer from significant degeneration, especially for tail labels. To address these issues, in this paper, we propose a novel Hierarchical Text Classification Optimization method via Structural Entropy and SIngular Spectrum Smoothing, namely SIHTC. SIHTC contains two parts: text embedding optimization and label embedding optimization. First, based on the structural information theory, we design a tree aggregation network and construct encoding trees to minimize the structural entropy of texts under the hierarchical labels. In this manner, SIHTC injects label structural information into text embeddings, hierarchically optimizing the embedding space by enclosing the text embeddings within related ground truth labels while separating them from unrelated ground truth labels. Second, we propose a global and local singular spectrum smoothing regularization method to maximize the area under the singular value curve. In this way, SIHTC decreases representation degeneration and learns label embeddings with improved label generalization capability. Extensive experiments are conducted on three popular HTC datasets. The results show that SIHTC outperforms all baseline methods, especially with an advantage in handling tail labels, indicating the effectiveness of the above two optimizations

There are anecdotal evidences that realtime mobile multiplayer games (RMMGs), which require realtime interactions, suffer from unsatisfying experience in the wild. This paper presents thefirst measurement results of such experience based on 12 million real game sessions from a toptier RMMG. We observe that 13% of the game sessions suffer from at least one location resynchronization, and 7.12% have been aborted abnormally before the end of the game. This paper thus proposes ExCause, a general causal analysis framework to systematically analyze historical game session records to 1) obtain context factors that cause unsatisfying RMMG experience, and 2) recommend adjustments with quantified expectation of QoE improvement, by applying the potential outcome framework. The recommendations suggested by ExCause can reduce the number of location resynchronization by 95.1%, from 1.323 to 0.065 on average. Furthermore, ExCause enables us to rectify some misperceptions from previous correlation-based studies.

Internet-based services monitor and detect anomalies on KPIs (Key Performance Indicators, say CPU utilization, number of queries per second, response latency) of their applications and systems in order to keep their services reliable. This paper identifies a common, important, yet little-studied problem of KPI anomaly detection: rapid deployment of anomaly detection models for large number of emerging KPI streams, without manual algorithm selection, parameter tuning, or new anomaly labeling for any newly emerging KPI streams. We propose the first framework ADS (Anomaly Detection through Self-training) that tackles the above problem, via clustering and semi-supervised learning. Our extensive experiments using real-world data show that, with the labels of only the 5 cluster centroids of 70 historical KPI streams, ADS achieves an averaged best F-score of 0.92 on 81 new KPI streams, almost the same as a state-of-art supervised approach, and greatly outperforming a state-of-art unsupervised approach by 61.40% on average.