Paper Overview
Research area: ML / Finance Authors: Cláudio Lúcio do Val Lopes, Lucca Machado da Silva Published: 2026-07-10 arXiv: 2607.09641
Summary
Financial anomaly detection is plagued by extreme class imbalance, which causes traditional single-objective algorithms to suffer from a "fraud collapse" — defaulting to predictions of the majority (non-fraudulent) class.
This paper proposes Semantic Pareto-DQN, a multi-objective reinforcement learning framework that addresses this problem through:
- LLM-based state representation: Heterogeneous transaction features are synthesized into coherent natural-language narratives encoded by large language models, producing robust and scale-invariant state representations.
- Decoupled multi-objective reward: The agent optimizes an explicit vectorized reward that separates financial efficacy, operational friction, and semantic discovery.
- Pareto front navigation: By mapping a continuous Pareto frontier, the framework dynamically navigates the asymmetric costs between missed anomalies (false negatives) and false alarms (false positives).
Results
Experiments on the E-Commerce fraud dataset and the UCI Credit dataset show that the framework successfully breaks out of the zero-recall trap, maintaining meaningful detection of rare fraudulent cases where conventional approaches collapse.
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