Statistical Learning
Robust Semi-Supervised CT Radiomics for Lung Cancer Prognosis: Cost-Effective Learning with Limited Labels and SHAP Interpretation
Salmanpour, Mohammad R., Pouria, Amir Hossein, Falahati, Sonia, Taeb, Shahram, Mehrnia, Somayeh Sadat, Maghsudi, Mehdi, Jouzdani, Ali Fathi, Oveisi, Mehrdad, Hacihaliloglu, Ilker, Rahmim, Arman
Background: CT imaging is vital for lung cancer management, offering detailed visualization for AI-based prognosis. However, supervised learning SL models require large labeled datasets, limiting their real-world application in settings with scarce annotations. Methods: We analyzed CT scans from 977 patients across 12 datasets extracting 1218 radiomics features using Laplacian of Gaussian and wavelet filters via PyRadiomics Dimensionality reduction was applied with 56 feature selection and extraction algorithms and 27 classifiers were benchmarked A semi supervised learning SSL framework with pseudo labeling utilized 478 unlabeled and 499 labeled cases Model sensitivity was tested in three scenarios varying labeled data in SL increasing unlabeled data in SSL and scaling both from 10 percent to 100 percent SHAP analysis was used to interpret predictions Cross validation and external testing in two cohorts were performed. Results: SSL outperformed SL, improving overall survival prediction by up to 17 percent. The top SSL model, Random Forest plus XGBoost classifier, achieved 0.90 accuracy in cross-validation and 0.88 externally. SHAP analysis revealed enhanced feature discriminability in both SSL and SL, especially for Class 1 survival greater than 4 years. SSL showed strong performance with only 10 percent labeled data, with more stable results compared to SL and lower variance across external testing, highlighting SSL's robustness and cost effectiveness. Conclusion: We introduced a cost-effective, stable, and interpretable SSL framework for CT-based survival prediction in lung cancer, improving performance, generalizability, and clinical readiness by integrating SHAP explainability and leveraging unlabeled data.
From On-chain to Macro: Assessing the Importance of Data Source Diversity in Cryptocurrency Market Forecasting
Demosthenous, Giorgos, Georgiou, Chryssis, Polydorou, Eliada
This study investigates the impact of data source diversity on the performance of cryptocurrency forecasting models by integrating various data categories, including technical indicators, on-chain metrics, sentiment and interest metrics, traditional market indices, and macroeconomic indicators. We introduce the Crypto100 index, representing the top 100 cryptocurrencies by market capitalization, and propose a novel feature reduction algorithm to identify the most impactful and resilient features from diverse data sources. Our comprehensive experiments demonstrate that data source diversity significantly enhances the predictive performance of forecasting models across different time horizons. Key findings include the paramount importance of on-chain metrics for both short-term and long-term predictions, the growing relevance of traditional market indices and macroeconomic indicators for longer-term forecasts, and substantial improvements in model accuracy when diverse data sources are utilized. These insights help demystify the short-term and long-term driving factors of the cryptocurrency market and lay the groundwork for developing more accurate and resilient forecasting models.
Prediction via Shapley Value Regression
Alkhatib, Amr, Bresson, Roman, Bostrรถm, Henrik, Vazirgiannis, Michalis
Shapley values have several desirable, theoretically well-supported, properties for explaining black-box model predictions. Traditionally, Shapley values are computed post-hoc, leading to additional computational cost at inference time. To overcome this, a novel method, called ViaSHAP, is proposed, that learns a function to compute Shapley values, from which the predictions can be derived directly by summation. Two approaches to implement the proposed method are explored; one based on the universal approximation theorem and the other on the Kolmogorov-Arnold representation theorem. Results from a large-scale empirical investigation are presented, showing that ViaSHAP using Kolmogorov-Arnold Networks performs on par with state-of-the-art algorithms for tabular data. It is also shown that the explanations of ViaSHAP are significantly more accurate than the popular approximator FastSHAP on both tabular data and images.
Characterizing gaussian mixture of motion modes for skid-steer vehicle state estimation
Salvi, Ameya, Brudnak, Mark, Smereka, Jonathon M., Schmid, Matthias, Krovi, Venkat
Skid-steered wheel mobile robots (SSWMRs) are characterized by the unique domination of the tire-terrain skidding for the robot to move. The lack of reliable friction models cascade into unreliable motion models, especially the reduced ordered variants used for state estimation and robot control. Ensemble modeling is an emerging research direction where the overall motion model is broken down into a family of local models to distribute the performance and resource requirement and provide a fast real-time prediction. To this end, a gaussian mixture model based modeling identification of model clusters is adopted and implemented within an interactive multiple model (IMM) based state estimation. The framework is adopted and implemented for angular velocity as the estimated state for a mid scaled skid-steered wheel mobile robot platform.
Geometric Learning Dynamics
We present a unified geometric framework for modeling learning dynamics in physical, biological, and machine learning systems. The theory reveals three fundamental regimes, each emerging from the power-law relationship $g \propto ฮบ^ฮฑ$ between the metric tensor $g$ in the space of trainable variables and the noise covariance matrix $ฮบ$. The quantum regime corresponds to $ฮฑ= 1$ and describes Schrรถdinger-like dynamics that emerges from a discrete shift symmetry. The efficient learning regime corresponds to $ฮฑ= \tfrac{1}{2}$ and describes very fast machine learning algorithms. The equilibration regime corresponds to $ฮฑ= 0$ and describes classical models of biological evolution. We argue that the emergence of the intermediate regime $ฮฑ= \tfrac{1}{2}$ is a key mechanism underlying the emergence of biological complexity.
Leveraging Large Language Models for Multi-Class and Multi-Label Detection of Drug Use and Overdose Symptoms on Social Media
Ahmad, Muhammad, Ullah, Fida, Usman, Muhammad, Habiba, Umyh, Batyrshin, ldar, Sidorov, Grigori
Drug overdose remains a critical global health issue, often driven by misuse of opioids, painkillers, and psychiatric medications. Traditional research methods face limitations, whereas social media offers real-time insights into self-reported substance use and overdose symptoms. This study proposes an AI-driven NLP framework trained on annotated social media data to detect commonly used drugs and associated overdose symptoms. Using a hybrid annotation strategy with LLMs and human annotators, we applied traditional ML models, neural networks, and advanced transformer-based models. Our framework achieved 98% accuracy in multi-class and 97% in multi-label classification, outperforming baseline models by up to 8%. These findings highlight the potential of AI for supporting public health surveillance and personalized intervention strategies.
D3FL: Data Distribution and Detrending for Robust Federated Learning in Non-linear Time-series Data
Marisetty, Harsha Varun, Gupta, Manik, Simmhan, Yogesh
With advancements in computing and communication technologies, the Internet of Things (IoT) has seen significant growth. IoT devices typically collect data from various sensors, such as temperature, humidity, and energy meters. Much of this data is temporal in nature. Traditionally, data from IoT devices is centralized for analysis, but this approach introduces delays and increased communication costs. Federated learning (FL) has emerged as an effective alternative, allowing for model training across distributed devices without the need to centralize data. In many applications, such as smart home energy and environmental monitoring, the data collected by IoT devices across different locations can exhibit significant variation in trends and seasonal patterns. Accurately forecasting such non-stationary, non-linear time-series data is crucial for applications like energy consumption estimation and weather forecasting. However, these data variations can severely impact prediction accuracy. The key contributions of this paper are: (1) Investigating how non-linear, non-stationary time-series data distributions, like generalized extreme value (gen-extreme) and log norm distributions, affect FL performance. (2) Analyzing how different detrending techniques for non-linear time-series data influence the forecasting model's performance in a FL setup. We generated several synthetic time-series datasets using non-linear data distributions and trained an LSTM-based forecasting model using both centralized and FL approaches. Additionally, we evaluated the impact of detrending on real-world datasets with non-linear time-series data distributions. Our experimental results show that: (1) FL performs worse than centralized approaches when dealing with non-linear data distributions. (2) The use of appropriate detrending techniques improves FL performance, reducing loss across different data distributions.
From Kinetic Theory to AI: a Rediscovery of High-Dimensional Divergences and Their Properties
Auricchio, Gennaro, Brigati, Giovanni, Giudici, Paolo, Toscani, Giuseppe
Selecting an appropriate divergence measure is a critical aspect of machine learning, as it directly impacts model performance. Among the most widely used, we find the Kullback-Leibler (KL) divergence, originally introduced in kinetic theory as a measure of relative entropy between probability distributions. Just as in machine learning, the ability to quantify the proximity of probability distributions plays a central role in kinetic theory. In this paper, we present a comparative review of divergence measures rooted in kinetic theory, highlighting their theoretical foundations and exploring their potential applications in machine learning and artificial intelligence.
A Parallelizable Approach for Characterizing NE in Zero-Sum Games After a Linear Number of Iterations of Gradient Descent
We study online optimization methods for zero-sum games, a fundamental problem in adversarial learning in machine learning, economics, and many other domains. Traditional methods approximate Nash equilibria (NE) using either regret-based methods (time-average convergence) or contraction-map-based methods (last-iterate convergence). We propose a new method based on Hamiltonian dynamics in physics and prove that it can characterize the set of NE in a finite (linear) number of iterations of alternating gradient descent in the unbounded setting, modulo degeneracy, a first in online optimization. Unlike standard methods for computing NE, our proposed approach can be parallelized and works with arbitrary learning rates, both firsts in algorithmic game theory. Experimentally, we support our results by showing our approach drastically outperforms standard methods.
LyAm: Robust Non-Convex Optimization for Stable Learning in Noisy Environments
Mirzabeigi, Elmira, Rezaee, Sepehr, Parand, Kourosh
Training deep neural networks for computer vision is inherently challenging due to issues like unstable gradients, local minima, and pervasive noisy data [48]. These challenges are magnified in anomalous environments where data distributions deviate from the norm, critically impairing the optimization process. Such instability hinders the model's ability to learn robust representations and significantly affects its generalization to unseen data. The choice of optimizer is central to alleviating these issues, as it governs both convergence speed and stability during training. Over the decades, various optimizers have been proposed to tackle different facets of this optimization challenge. Early work on Stochastic Gradient Descent (SGD) [30, 33] laid the foundation for iterative gradient-based methods by employing a simple yet effective parameter update scheme. AdaGrad [4] introduced per-parameter learning rate adjustments to better handle sparse gradients, while Adam [13] fused momentum-based updates with adaptive learning rates, accelerating convergence. Subsequently, Adam variants such as AdamW [23], AdaBelief [52], and Adan [21] have sought to address limitations in Adam's adaptive mechanism and enhance robustness in complex, non-convex landscapes.