Published Papers

Large language models (LLMs) have proven themselves to be powerful tools for many natural language tasks — from being a high-quality text classifiers to acting as agents in complex retrieval-augmented generation (RAG) systems. However, from early beggining they suffer from a major limitation: hallucinations, i.e. confidently generating incorrect or misleading information that can also slightly correlate with the given task. This issue is critical in error-sensitive domains such as finance, medicine, and law, where even small inaccuracies can cause significant harm and detriment. In this study we address the early detection of hallucinating answers based on user input (prompt), answer by the LLM, and which is more important — token-level probabilty signals that can also be extracted from the LLM during its inference time. We constructed a dataset that combines textual information with sequences of token log-probabilities and their statistics (mean, min, variance, percentiles, etc.), labeled the answers whether they are hallucinations or not. We trained a lightweight classifier that outputs the probability that a given response is a hallucination. We evaluate the classifier and perform ablation studies to quantify the contribution of token-level signals versus text-only features. The intended use of the trained model is to be a standalone output guard agent in multi-agent system that rejects the answer of LLM-generator if its hallucination probability is above acceptance threshold and protects the users of it from having incorrect or misleading answer by making the whole system regenerate such answer or confirm that it cannot give the faithfull reply.