Ponti, Moacir Antonelli
Real-Time Anomaly Detection with Synthetic Anomaly Monitoring (SAM)
Luzio, Emanuele, Ponti, Moacir Antonelli
Anomaly detection is essential for identifying rare and significant events across diverse domains such as finance, cybersecurity, and network monitoring. This paper presents Synthetic Anomaly Monitoring (SAM), an innovative approach that applies synthetic control methods from causal inference to improve both the accuracy and interpretability of anomaly detection processes. By modeling normal behavior through the treatment of each feature as a control unit, SAM identifies anomalies as deviations within this causal framework. We conducted extensive experiments comparing SAM with established benchmark models, including Isolation Forest, Local Outlier Factor (LOF), k-Nearest Neighbors (kNN), and One-Class Support Vector Machine (SVM), across five diverse datasets, including Credit Card Fraud, HTTP Dataset CSIC 2010, and KDD Cup 1999, among others. Our results demonstrate that SAM consistently delivers robust performance, highlighting its potential as a powerful tool for real-time anomaly detection in dynamic and complex environments.
Decoupling Decision-Making in Fraud Prevention through Classifier Calibration for Business Logic Action
Luzio, Emanuele, Ponti, Moacir Antonelli, Arevalo, Christian Ramirez, Argerich, Luis
Machine learning models typically focus on specific targets like creating classifiers, often based on known population feature distributions in a business context. However, models calculating individual features adapt over time to improve precision, introducing the concept of decoupling: shifting from point evaluation to data distribution. We use calibration strategies as strategy for decoupling machine learning (ML) classifiers from score-based actions within business logic frameworks. To evaluate these strategies, we perform a comparative analysis using a real-world business scenario and multiple ML models. Our findings highlight the trade-offs and performance implications of the approach, offering valuable insights for practitioners seeking to optimize their decoupling efforts. In particular, the Isotonic and Beta calibration methods stand out for scenarios in which there is shift between training and testing data.
Dendrogram distance: an evaluation metric for generative networks using hierarchical clustering
Carvalho, Gustavo Sutter, Ponti, Moacir Antonelli
Generative modeling is a task that aims to estimate the generation process of a given source dataset. Models obtained as a result of this approach can be used to sample novel data points that follow the distribution of the source training set, allowing for different applications in machine learning. Performing generative modeling using neural networks has become very popular mainly because of the success of Generative Adversarial Networks (GANs) (Goodfellow et al., 2014) and later with Diffusion models (Luo, 2022). The GAN framework relies on two different networks, a generator and a discriminator, that compete against their selves to perform the generative task, as shown in Figure 1. Figure 1: Diagram that illustrates the different components of GAN. The generator network G transforms a random input z into samples that should be realistic, while the discriminator network D tells apart which samples came from the training data.
YourTTS: Towards Zero-Shot Multi-Speaker TTS and Zero-Shot Voice Conversion for everyone
Casanova, Edresson, Weber, Julian, Shulby, Christopher, Junior, Arnaldo Candido, Gölge, Eren, Ponti, Moacir Antonelli
YourTTS brings the power of a multilingual approach to the task of zero-shot multi-speaker TTS. Our method builds upon the VITS model and adds several novel modifications for zero-shot multi-speaker and multilingual training. We achieved state-of-the-art (SOTA) results in zero-shot multi-speaker TTS and results comparable to SOTA in zero-shot voice conversion on the VCTK dataset. Additionally, our approach achieves promising results in a target language with a single-speaker dataset, opening possibilities for zero-shot multi-speaker TTS and zero-shot voice conversion systems in low-resource languages. Finally, it is possible to fine-tune the YourTTS model with less than 1 minute of speech and achieve state-of-the-art results in voice similarity and with reasonable quality. This is important to allow synthesis for speakers with a very different voice or recording characteristics from those seen during training.
Como funciona o Deep Learning
Ponti, Moacir Antonelli, da Costa, Gabriel B. Paranhos
Deep Learning methods are currently the state-of-the-art in many problems which can be tackled via machine learning, in particular classification problems. However there is still lack of understanding on how those methods work, why they work and what are the limitations involved in using them. In this chapter we will describe in detail the transition from shallow to deep networks, include examples of code on how to implement them, as well as the main issues one faces when training a deep network. Afterwards, we introduce some theoretical background behind the use of deep models, and discuss their limitations.
Computing the Shattering Coefficient of Supervised Learning Algorithms
de Mello, Rodrigo Fernandes, Ponti, Moacir Antonelli, Ferreira, Carlos Henrique Grossi
The Statistical Learning Theory (SLT) provides the theoretical guarantees for supervised machine learning based on the Empirical Risk Minimization Principle (ERMP). Such principle defines an upper bound to ensure the uniform convergence of the empirical risk Remp(f), i.e., the error measured on a given data sample, to the expected value of risk R(f) (a.k.a. actual risk), which depends on the Joint Probability Distribution P(X x Y) mapping input examples x in X to class labels y in Y. The uniform convergence is only ensured when the Shattering coefficient N(F,2n) has a polynomial growing behavior. This paper proves the Shattering coefficient for any Hilbert space H containing the input space X and discusses its effects in terms of learning guarantees for supervised machine algorithms.