Statistical Learning
Large language models for folktale type automation based on motifs: Cinderella case study
Arčon, Tjaša, Robnik-Šikonja, Marko, Tratnik, Polona
Artificial intelligence approaches are being adapted to many research areas, including digital humanities. We built a methodology for large-scale analyses in folkloristics. Using machine learning and natural language processing, we automatically detected motifs in a large collection of Cinderella variants and analysed their similarities and differences with clustering and dimensionality reduction. The results show that large language models detect complex interactions in tales, enabling computational analysis of extensive text collections and facilitating cross-lingual comparisons.
Simple and Efficient Heterogeneous Temporal Graph Neural Network
Wang, Yili, Huang, Tairan, He, Changlong, Li, Qiutong, Gao, Jianliang
Heterogeneous temporal graphs (HTGs) are ubiquitous data structures in the real world. Recently, to enhance representation learning on HTGs, numerous attention-based neural networks have been proposed. Despite these successes, existing methods rely on a decoupled temporal and spatial learning paradigm, which weakens interactions of spatio-temporal information and leads to a high model complexity. To bridge this gap, we propose a novel learning paradigm for HTGs called Simple and Efficient Heterogeneous Temporal Graph N}eural Network (SE-HTGNN). Specifically, we innovatively integrate temporal modeling into spatial learning via a novel dynamic attention mechanism, which retains attention information from historical graph snapshots to guide subsequent attention computation, thereby improving the overall discriminative representations learning of HTGs. Additionally, to comprehensively and adaptively understand HTGs, we leverage large language models to prompt SE-HTGNN, enabling the model to capture the implicit properties of node types as prior knowledge. Extensive experiments demonstrate that SE-HTGNN achieves up to 10x speed-up over the state-of-the-art and latest baseline while maintaining the best forecasting accuracy.
Towards Unsupervised Open-Set Graph Domain Adaptation via Dual Reprogramming
Unsupervised Graph Domain Adaptation has become a promisin g paradigm for transferring knowledge from a fully labeled source graph to an unlabeled target graph. Existing graph domain adaptation models primarily f ocus on the closed-set setting, where the source and target domains share the same l abel spaces. However, this assumption might not be practical in the real-wor ld scenarios, as the target domain might include classes that are not present in t he source domain. In this paper, we investigate the problem of unsupervised open -set graph domain adaptation, where the goal is to not only correctly classify target nodes into the known classes, but also recognize previously unseen node ty pes into the unknown class. Towards this end, we propose a novel framework called GraphRT A, which conducts reprogramming on both the graph and model sides. Sp ecifically, we reprogram the graph by modifying target graph structure and no de features, which facilitates better separation of known and unknown classes . Meanwhile, we also perform model reprogramming by pruning domain-specific par ameters to reduce bias towards the source graph while preserving parameters t hat capture transferable patterns across graphs. Additionally, we extend the cl assifier with an extra dimension for the unknown class, thus eliminating the need o f manually specified threshold in open-set recognition. Comprehensive experim ents on several public datasets demonstrate that our proposed model can achieve sa tisfied performance compared with recent state-of-the-art baselines.
Online Time Series Forecasting with Theoretical Guarantees
Li, Zijian, Zhou, Changze, Fu, Minghao, Manjunath, Sanjay, Feng, Fan, Chen, Guangyi, Hu, Yingyao, Cai, Ruichu, Zhang, Kun
This paper is concerned with online time series forecasting, where unknown distribution shifts occur over time, i.e., latent variables influence the mapping from historical to future observations. To develop an automated way of online time series forecasting, we propose a Theoretical framework for Online Time-series forecasting (TOT in short) with theoretical guarantees. Specifically, we prove that supplying a forecaster with latent variables tightens the Bayes risk, the benefit endures under estimation uncertainty of latent variables and grows as the latent variables achieve a more precise identifiability. To better introduce latent variables into online forecasting algorithms, we further propose to identify latent variables with minimal adjacent observations. Based on these results, we devise a model-agnostic blueprint by employing a temporal decoder to match the distribution of observed variables and two independent noise estimators to model the causal inference of latent variables and mixing procedures of observed variables, respectively. Experiment results on synthetic data support our theoretical claims. Moreover, plug-in implementations built on several baselines yield general improvement across multiple benchmarks, highlighting the effectiveness in real-world applications.
Latent-Info and Low-Dimensional Learning for Human Mesh Recovery and Parallel Optimization
Zhang, Xiang, Wu, Suping, Yang, Sheng
Existing 3D human mesh recovery methods often fail to fully exploit the latent information (e.g., human motion, shape alignment), leading to issues with limb misalignment and insufficient local details in the reconstructed human mesh (especially in complex scenes). Furthermore, the performance improvement gained by modelling mesh vertices and pose node interactions using attention mechanisms comes at a high computational cost. To address these issues, we propose a two-stage network for human mesh recovery based on latent information and low dimensional learning. Specifically, the first stage of the network fully excavates global (e.g., the overall shape alignment) and local (e.g., textures, detail) information from the low and high-frequency components of image features and aggregates this information into a hybrid latent frequency domain feature. This strategy effectively extracts latent information. Subsequently, utilizing extracted hybrid latent frequency domain features collaborates to enhance 2D poses to 3D learning. In the second stage, with the assistance of hybrid latent features, we model the interaction learning between the rough 3D human mesh template and the 3D pose, optimizing the pose and shape of the human mesh. Unlike existing mesh pose interaction methods, we design a low-dimensional mesh pose interaction method through dimensionality reduction and parallel optimization that significantly reduces computational costs without sacrificing reconstruction accuracy. Extensive experimental results on large publicly available datasets indicate superiority compared to the most state-of-the-art.
Finding the Sweet Spot: Optimal Data Augmentation Ratio for Imbalanced Credit Scoring Using ADASYN
Credit scoring models face a critical challenge: severe class imbalance, with default rates typically below 10%, which hampers model learning and predictive performance. While synthetic data augmentation techniques such as SMOTE and ADASYN have been proposed to address this issue, the optimal augmentation ratio remains unclear, with practitioners often defaulting to full balancing (1:1 ratio) without empirical justification. This study systematically evaluates 10 data augmentation scenarios using the Give Me Some Credit dataset (97,243 observations, 7% default rate), comparing SMOTE, BorderlineSMOTE, and ADASYN at different multiplication factors (1x, 2x, 3x). All models were trained using XGBoost and evaluated on a held-out test set of 29,173 real observations. Statistical significance was assessed using bootstrap testing with 1,000 iterations. Key findings reveal that ADASYN with 1x multiplication (doubling the minority class) achieved optimal performance with AUC of 0.6778 and Gini coefficient of 0.3557, representing statistically significant improvements of +0.77% and +3.00% respectively (p = 0.017, bootstrap test). Higher multiplication factors (2x and 3x) resulted in performance degradation, with 3x showing a -0.48% decrease in AUC, suggesting a "law of diminishing returns" for synthetic oversampling. The optimal class imbalance ratio was found to be 6.6:1 (majority:minority), contradicting the common practice of balancing to 1:1. This work provides the first empirical evidence of an optimal "sweet spot" for data augmentation in credit scoring, with practical guidelines for industry practitioners and researchers working with imbalanced datasets. While demonstrated on a single representative dataset, the methodology provides a reproducible framework for determining optimal augmentation ratios in other imbalanced domains.
Enhancing mortality prediction in cardiac arrest ICU patients through meta-modeling of structured clinical data from MIMIC-IV
Mamatov, Nursultan, Kellmeyer, Philipp
Accurate early prediction of in-hospital mortality in intensive care units (ICUs) is essential for timely clinical intervention and efficient resource allocation. This study develops and evaluates machine learning models that integrate both structured clinical data and unstructured textual information, specifically discharge summaries and radiology reports, from the MIMIC-IV database. We used LASSO and XGBoost for feature selection, followed by a multivariate logistic regression trained on the top features identified by both models. Incorporating textual features using TF-IDF and BERT embeddings significantly improved predictive performance. The final logistic regression model, which combined structured and textual input, achieved an AUC of 0.918, compared to 0.753 when using structured data alone, a relative improvement 22%. The analysis of the decision curve demonstrated a superior standardized net benefit in a wide range of threshold probabilities (0.2-0.8), confirming the clinical utility of the model. These results underscore the added prognostic value of unstructured clinical notes and support their integration into interpretable feature-driven risk prediction models for ICU patients.
Measure-Theoretic Anti-Causal Representation Learning
Causal representation learning in the anti-causal setting (labels cause features rather than the reverse) presents unique challenges requiring specialized approaches. We propose Anti-Causal Invariant Abstractions (ACIA), a novel measure-theoretic framework for anti-causal representation learning. ACIA employs a two-level design, low-level representations capture how labels generate observations, while high-level representations learn stable causal patterns across environment-specific variations. ACIA addresses key limitations of existing approaches by accommodating prefect and imperfect interventions through interventional kernels, eliminating dependency on explicit causal structures, handling high-dimensional data effectively, and providing theoretical guarantees for out-of-distribution generalization. Experiments on synthetic and real-world medical datasets demonstrate that ACIA consistently outperforms state-of-the-art methods in both accuracy and invariance metrics. Furthermore, our theoretical results establish tight bounds on performance gaps between training and unseen environments, confirming the efficacy of our approach for robust anti-causal learning.
Attention-Guided Deep Adversarial Temporal Subspace Clustering (A-DATSC) Model for multivariate spatiotemporal data
Nji, Francis Ndikum, Janeja, Vandana, Wang, Jianwu
Deep subspace clustering models are vital for applications such as snowmelt detection, sea ice tracking, crop health monitoring, infectious disease modeling, network load prediction, and land-use planning, where multivariate spatiotemporal data exhibit complex temporal dependencies and reside on multiple nonlinear manifolds beyond the capability of traditional clustering methods. These models project data into a latent space where samples lie in linear subspaces and exploit the self-expressiveness property to uncover intrinsic relationships. Despite their success, existing methods face major limitations: they use shallow autoencoders that ignore clustering errors, emphasize global features while neglecting local structure, fail to model long-range dependencies and positional information, and are rarely applied to 4D spatiotemporal data. To address these issues, we propose A-DATSC (Attention-Guided Deep Adversarial Temporal Subspace Clustering), a model combining a deep subspace clustering generator and a quality-verifying discriminator. The generator, inspired by U-Net, preserves spatial and temporal integrity through stacked TimeDistributed ConvLSTM2D layers, reducing parameters and enhancing generalization. A graph attention transformer based self-expressive network captures local spatial relationships, global dependencies, and both short- and long-range correlations. Experiments on three real-world multivariate spatiotemporal datasets show that A-DATSC achieves substantially superior clustering performance compared to state-of-the-art deep subspace clustering models.
SimBA: Simplifying Benchmark Analysis Using Performance Matrices Alone
Subramani, Nishant, Gomez, Alfredo, Diab, Mona
Modern language models are evaluated on large benchmarks, which are difficult to make sense of, especially for model selection. Looking at the raw evaluation numbers themselves using a model-centric lens, we propose SimBA, a three phase framework to Simplify Benchmark Analysis. The three phases of SimBA are: stalk, where we conduct dataset & model comparisons, prowl, where we discover a representative subset, and pounce, where we use the representative subset to predict performance on a held-out set of models. Applying SimBA to three popular LM benchmarks: HELM, MMLU, and BigBenchLite reveals that across all three benchmarks, datasets and models relate strongly to one another (stalk). We develop an representative set discovery algorithm which covers a benchmark using raw evaluation scores alone. Using our algorithm, we find that with 6.25% (1/16), 1.7% (1/58), and 28.4% (21/74) of the datasets for HELM, MMLU, and BigBenchLite respectively, we achieve coverage levels of at least 95% (prowl). Additionally, using just these representative subsets, we can both preserve model ranks and predict performance on a held-out set of models with near zero mean-squared error (pounce). Taken together, SimBA can help model developers improve efficiency during model training and dataset creators validate whether their newly created dataset differs from existing datasets in a benchmark. Our code is open source, available at https://github.com/nishantsubramani/simba.