Author name cluster

Marco Romanelli 0002

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5 papers

1 author row

UAI Conference 2025 Conference Paper

Optimal Zero-shot Regret Minimization for Selective Classification with Out-of-Distribution Detection

Eduardo Dadalto Câmara Gomes
Marco Romanelli 0002

Selective Classification with Out-of-Distribution Detection (SCOD) is a general framework that combines the detection of incorrectly classified in-distribution samples and out-of-distribution samples. Previous solutions for SCOD heavily rely on the choice of Selective Classification (SC) and Out-of-Distribution (OOD) detectors selected at test time. Notably, the performance of these detectors varies across different underlying data distributions. Hence, a poor choice can affect the efficacy of the SCOD framework. On the other hand, making an informed choice is impossible without samples from both in- and out-distribution. We propose an optimal zero-shot black-box method for SCOD that aggregates off-the-shelf detectors, is based on the principle of regret minimization, and therefore provides guarantees on the worst-case performance. We demonstrate that our method achieves performance comparable to state-of-the-art methods in several benchmarks while also shielding the user from the burden of blindly selecting the SC and OOD detectors, optimally reducing the worst-case rejection risk.

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ICLR Conference 2024 Conference Paper

A Data-Driven Measure of Relative Uncertainty for Misclassification Detection

Eduardo Dadalto Câmara Gomes
Marco Romanelli 0002
Georg Pichler
Pablo Piantanida

Misclassification detection is an important problem in machine learning, as it allows for the identification of instances where the model's predictions are unreliable. However, conventional uncertainty measures such as Shannon entropy do not provide an effective way to infer the real uncertainty associated with the model's predictions. In this paper, we introduce a novel data-driven measure of uncertainty relative to an observer for misclassification detection. By learning patterns in the distribution of soft-predictions, our uncertainty measure can identify misclassified samples based on the predicted class probabilities. Interestingly, according to the proposed measure, soft-predictions corresponding to misclassified instances can carry a large amount of uncertainty, even though they may have low Shannon entropy. We demonstrate empirical improvements over multiple image classification tasks, outperforming state-of-the-art misclassification detection methods.

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ICML Conference 2024 Conference Paper

Beyond the Norms: Detecting Prediction Errors in Regression Models

Andrés Altieri
Marco Romanelli 0002
Georg Pichler
Florence Alberge
Pablo Piantanida

This paper tackles the challenge of detecting unreliable behavior in regression algorithms, which may arise from intrinsic variability (e. g. , aleatoric uncertainty) or modeling errors (e. g. , model uncertainty). First, we formally introduce the notion of unreliability in regression, i. e. , when the output of the regressor exceeds a specified discrepancy (or error). Then, using powerful tools for probabilistic modeling, we estimate the discrepancy density, and we measure its statistical diversity using our proposed metric for statistical dissimilarity. In turn, this allows us to derive a data-driven score that expresses the uncertainty of the regression outcome. We show empirical improvements in error detection for multiple regression tasks, consistently outperforming popular baseline approaches, and contributing to the broader field of uncertainty quantification and safe machine learning systems.

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ICML Conference 2024 Conference Paper

Disparate Impact on Group Accuracy of Linearization for Private Inference

Saswat Das
Marco Romanelli 0002
Ferdinando Fioretto

Ensuring privacy-preserving inference on cryptographically secure data is a well-known computational challenge. To alleviate the bottleneck of costly cryptographic computations in non-linear activations, recent methods have suggested linearizing a targeted portion of these activations in neural networks. This technique results in significantly reduced runtimes with often negligible impacts on accuracy. In this paper, we demonstrate that such computational benefits may lead to increased fairness costs. Specifically, we find that reducing the number of ReLU activations disproportionately decreases the accuracy for minority groups compared to majority groups. To explain these observations, we provide a mathematical interpretation under restricted assumptions about the nature of the decision boundary, while also showing the prevalence of this problem across widely used datasets and architectures. Finally, we show how a simple procedure altering the finetuning step for linearized models can serve as an effective mitigation strategy.

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ICLR Conference 2024 Conference Paper

Retrieval-Guided Reinforcement Learning for Boolean Circuit Minimization

Animesh Basak Chowdhury
Marco Romanelli 0002
Benjamin Tan 0001
Ramesh Karri
Siddharth Garg

Logic synthesis, a pivotal stage in chip design, entails optimizing chip specifications encoded in hardware description languages like Verilog into highly efficient implementations using Boolean logic gates. The process involves a sequential application of logic minimization heuristics (``synthesis recipe"), with their arrangement significantly impacting crucial metrics such as area and delay. Addressing the challenge posed by the broad spectrum of hardware design complexities — from variations of past designs (e.g., adders and multipliers) to entirely novel configurations (e.g., innovative processor instructions) — requires a nuanced 'synthesis recipe' guided by human expertise and intuition. This study conducts a thorough examination of learning and search techniques for logic synthesis, unearthing a surprising revelation: pre-trained agents, when confronted with entirely novel designs, may veer off course, detrimentally affecting the search trajectory. We present ABC-RL, a meticulously tuned $\alpha$ parameter that adeptly adjusts recommendations from pre-trained agents during the search process. Computed based on similarity scores through nearest neighbor retrieval from the training dataset, ABC-RL yields superior synthesis recipes tailored for a wide array of hardware designs. Our findings showcase substantial enhancements in the Quality of Result (QoR) of synthesized circuits, boasting improvements of up to 24.8\% compared to state-of-the-art techniques. Furthermore, ABC-RL achieves an impressive up to 9x reduction in runtime (iso-QoR) when compared to current state-of-the-art methodologies.

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