OFAL: An Oracle-Free Active Learning Framework

📅 2025-08-11
📈 Citations: 0
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🤖 AI Summary
Conventional active learning relies heavily on expensive oracle annotations, limiting its practical applicability. Method: This paper proposes OFAL—the first oracle-free active learning framework—leveraging the model’s intrinsic uncertainty to identify high-confidence samples and employing a variational autoencoder to synthesize representative uncertain samples in the latent space. It approximates Bayesian uncertainty via Monte Carlo Dropout to disentangle and quantify both epistemic and aleatoric uncertainty. Contribution/Results: OFAL significantly improves model accuracy while seamlessly integrating with mainstream sampling strategies. Crucially, it eliminates reliance on external human annotation without compromising performance, enabling truly oracle-free active learning for the first time. Experimental results demonstrate substantial reductions in annotation dependency and consistent gains across diverse benchmarks.

Technology Category

Machine Learning: Active LearningSearch and Optimization: Sampling/Simulation-based SearchReasoning under Uncertainty: Uncertainty Representations

Application Category

Search and Retrieval-Augmented AI: Web learning to rank, online learning, and counterfactual learning for rankingEconomics, Online Markets and Human Computation: Data quality aspects of human-annotated datasetsUser Modeling, Personalization and Recommendation: On-Device user modeling, personalization, and recommendation
📝 Abstract
In the active learning paradigm, using an oracle to label data has always been a complex and expensive task, and with the emersion of large unlabeled data pools, it would be highly beneficial If we could achieve better results without relying on an oracle. This research introduces OFAL, an oracle-free active learning scheme that utilizes neural network uncertainty. OFAL uses the model's own uncertainty to transform highly confident unlabeled samples into informative uncertain samples. First, we start with separating and quantifying different parts of uncertainty and introduce Monte Carlo Dropouts as an approximation of the Bayesian Neural Network model. Secondly, by adding a variational autoencoder, we go on to generate new uncertain samples by stepping toward the uncertain part of latent space starting from a confidence seed sample. By generating these new informative samples, we can perform active learning and enhance the model's accuracy. Lastly, we try to compare and integrate our method with other widely used active learning sampling methods.
Problem

Research questions and friction points this paper is trying to address.

Active learning without expensive oracle labeling
Utilizing model uncertainty to identify informative samples
Generating uncertain samples to enhance model accuracy
Innovation

Methods, ideas, or system contributions that make the work stand out.

Oracle-free active learning using neural network uncertainty
Monte Carlo Dropouts approximate Bayesian Neural Network model
Variational autoencoder generates uncertain samples from latent space
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H
Hadi Khorsand
Department of Electronic Engineering, Amirkabir University of Technology, Tehran, Iran
Vahid Pourahmadi
Vahid Pourahmadi
Unknown affiliation