Support Vector Machines
But How Does It Work in Theory? Linear SVM with Random Features
We prove that, under low noise assumptions, the support vector machine with $N\ll m$ random features (RFSVM) can achieve the learning rate faster than $O(1/\sqrt{m})$ on a training set with $m$ samples when an optimized feature map is used. Our work extends the previous fast rate analysis of random features method from least square loss to 0-1 loss. We also show that the reweighted feature selection method, which approximates the optimized feature map, helps improve the performance of RFSVM in experiments on a synthetic data set.
PAC-Bayes bounds for stable algorithms with instance-dependent priors
Omar Rivasplata, Csaba Szepesvari, John S. Shawe-Taylor, Emilio Parrado-Hernandez, Shiliang Sun
P AC-Bayes bounds have been proposed to get risk estimates based on a training sample. In this paper the P AC-Bayes approach is combined with stability of the hypothesis learned by a Hilbert space valued algorithm. The P AC-Bayes setting is used with a Gaussian prior centered at the expected output. Thus a novelty of our paper is using priors defined in terms of the data-generating distribution. Our main result estimates the risk of the randomized algorithm in terms of the hypothesis stability coefficients. We also provide a new bound for the SVM classifier, which is compared to other known bounds experimentally. Ours appears to be the first uniform hypothesis stability-based bound that evaluates to non-trivial values.
Motor Imagery Classification Using Feature Fusion of Spatially Weighted Electroencephalography
Shiam, Abdullah Al, Molla, Md. Khademul Islam, Miah, Abu Saleh Musa, Kamal, Md. Abdus Samad
A Brain Computer Interface (BCI) connects the human brain to the outside world, providing a direct communication channel. Electroencephalography (EEG) signals are commonly used in BCIs to reflect cognitive patterns related to motor function activities. However, due to the multichannel nature of EEG signals, explicit information processing is crucial to lessen computational complexity in BCI systems. This study proposes an innovative method based on brain region-specific channel selection and multi-domain feature fusion to improve classification accuracy. The novelty of the proposed approach lies in region-based channel selection, where EEG channels are grouped according to their functional relevance to distinct brain regions. By selecting channels based on specific regions involved in motor imagery (MI) tasks, this technique eliminates irrelevant channels, reducing data dimensionality and improving computational efficiency. This also ensures that the extracted features are more reflective of the brain actual activity related to motor tasks. Three distinct feature extraction methods Common Spatial Pattern (CSP), Fuzzy C-means clustering, and Tangent Space Mapping (TSM), are applied to each group of channels based on their brain region. Each method targets different characteristics of the EEG signal: CSP focuses on spatial patterns, Fuzzy C means identifies clusters within the data, and TSM captures non-linear patterns in the signal. The combined feature vector is used to classify motor imagery tasks (left hand, right hand, and right foot) using Support Vector Machine (SVM). The proposed method was validated on publicly available benchmark EEG datasets (IVA and I) from the BCI competition III and IV. The results show that the approach outperforms existing methods, achieving classification accuracies of 90.77% and 84.50% for datasets IVA and I, respectively.
A Review of Statistical and Machine Learning Approaches for Coral Bleaching Assessment
Coral bleaching is a major concern for marine ecosystems; more than half of the world's coral reefs have either bleached or died over the past three decades. Increasing sea surface temperatures, along with various spatiotemporal environmental factors, are considered the primary reasons behind coral bleaching. The statistical and machine learning communities have focused on multiple aspects of the environment in detail. However, the literature on various stochastic modeling approaches for assessing coral bleaching is extremely scarce. Data-driven strategies are crucial for effective reef management, and this review article provides an overview of existing statistical and machine learning methods for assessing coral bleaching. Statistical frameworks, including simple regression models, generalized linear models, generalized additive models, Bayesian regression models, spatiotemporal models, and resilience indicators, such as Fisher's Information and Variance Index, are commonly used to explore how different environmental stressors influence coral bleaching. On the other hand, machine learning methods, including random forests, decision trees, support vector machines, and spatial operators, are more popular for detecting nonlinear relationships, analyzing high-dimensional data, and allowing integration of heterogeneous data from diverse sources. In addition to summarizing these models, we also discuss potential data-driven future research directions, with a focus on constructing statistical and machine learning models in specific contexts related to coral bleaching.
Enhanced Water Leak Detection with Convolutional Neural Networks and One-Class Support Vector Machine
Leonzio, Daniele Ugo, Bestagini, Paolo, Marcon, Marco, Tubaro, Stefano
Water is a critical resource that must be managed efficiently. However, a substantial amount of water is lost each year due to leaks in Water Distribution Networks (WDNs). This underscores the need for reliable and effective leak detection and localization systems. In recent years, various solutions have been proposed, with data-driven approaches gaining increasing attention due to their superior performance. In this paper, we propose a new method for leak detection. The method is based on water pressure measurements acquired at a series of nodes of a WDN. Our technique is a fully data-driven solution that makes only use of the knowledge of the WDN topology, and a series of pressure data acquisitions obtained in absence of leaks. The proposed solution is based on an feature extractor and a one-class Support Vector Machines (SVM) trained on no-leak data, so that leaks are detected as anomalies. The results achieved on a simulate dataset using the Modena WDN demonstrate that the proposed solution outperforms recent methods for leak detection.
Benchmarking Quantum Kernels Across Diverse and Complex Data
Quantum kernel methods have shown promise and are gaining growing use among quantum machine learning approaches to enhance the performance of kernel-based models, where support vector machines (SVMs) are a common example [1]. They have been applied to various machine learning tasks, such as classification of medical data or high-energy physics [2, 3]. An advanced enhancement to these kernel methods is the trainable quantum kernel, which employs a parameterized quantum circuit (PQC), often referred to as an ansatz. Here, a quantum circuit's gate operations are controlled by a set of externally optimized classical parameters [4, 5]. This enables the quantum kernel to be trained and adapted to the specific structure of a dataset [6]. However, despite theoretical promise, the practical deployment of quantum kernel methods is still in its very early stages. Many research studies focus on a single specific machine learning area with a few dataset samples, but an evaluation of the performance of a quantum kernel across diverse domains remains unverified, whereas this ability is common in classical kernel methods such as the linear kernel or Radial Basis Function (RBF) kernel [7]. This makes it difficult to understand the characteristics of the methods' performance from a comprehensive perspective. Furthermore, existing practice is primarily conducted on low-dimensional synthetic or introductory datasets like variants of MNIST or Iris, or aggressively reduced real-world data that goes from hundreds or more to around ten features [8-10], leaving a large gap in its application to real-world machine learning scenarios.
Embedding-Aware Quantum-Classical SVMs for Scalable Quantum Machine Learning
Ordรณรฑez, Sebastiรกn Andrรฉs Cajas, Torres, Luis Fernando Torres, Bifulco, Mario, Durรกn, Carlos Andrรฉs, Bosch, Cristian, Carbajo, Ricardo Simรณn
Quantum Support Vector Machines face scalability challenges due to high-dimensional quantum states and hardware limitations. We propose an embedding-aware quantum-classical pipeline combining class-balanced k-means distillation with pretrained Vision Transformer embeddings. Our key finding: ViT embeddings uniquely enable quantum advantage, achieving up to 8.02% accuracy improvements over classical SVMs on Fashion-MNIST and 4.42% on MNIST, while CNN features show performance degradation. Using 16-qubit tensor network simulation via cuTensorNet, we provide the first systematic evidence that quantum kernel advantage depends critically on embedding choice, revealing fundamental synergy between transformer attention and quantum feature spaces. This provides a practical pathway for scalable quantum machine learning that leverages modern neural architectures.
Rewiring Human Brain Networks via Lightweight Dynamic Connectivity Framework: An EEG-Based Stress Validation
Acharya, Sayantan, Khosravi, Abbas, Creighton, Douglas, Alizadehsani, Roohallah, Acharya, U. Rajendra
In recent years, Electroencephalographic analysis has gained prominence in stress research when combined with AI and Machine Learning models for validation. In this study, a lightweight dynamic brain connectivity framework based on Time Varying Directed Transfer Function is proposed, where TV DTF features were validated through ML based stress classification. TV DTF estimates the directional information flow between brain regions across distinct EEG frequency bands, thereby capturing temporal and causal influences that are often overlooked by static functional connectivity measures. EEG recordings from the 32 channel SAM 40 dataset were employed, focusing on mental arithmetic task trials. The dynamic EEG-based TV-DTF features were validated through ML classifiers such as Support Vector Machine, Random Forest, Gradient Boosting, Adaptive Boosting, and Extreme Gradient Boosting. Experimental results show that alpha-TV-DTF provided the strongest discriminative power, with SVM achieving 89.73% accuracy in 3-class classification and with XGBoost achieving 93.69% accuracy in 2 class classification. Relative to absolute power and phase locking based functional connectivity features, alpha TV DTF and beta TV DTF achieved higher performance across the ML models, highlighting the advantages of dynamic over static measures. Feature importance analysis further highlighted dominant long-range frontal parietal and frontal occipital informational influences, emphasizing the regulatory role of frontal regions under stress. These findings validate the lightweight TV-DTF as a robust framework, revealing spatiotemporal brain dynamics and directional influences across different stress levels.