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A Knowledge-Augmented Generation Framework for Question Answering Systems: Formalization, Architecture, and Evaluation

Andrea La Mantia

Electronic Theses and Dissertations Repository (University of Pisa), 2026

Abstract

This thesis presents the formalization, design, and evaluation of a Question Answering (QA) system based on the Knowledge-Augmented Generation (KAG) paradigm for the domain of police reports. The work addresses the need for reliable and explainable access to complex document collections characterized by sensitive information, rich relational structures, and strict accuracy requirements. The proposed framework integrates hybrid retrieval, graph-based evidence extraction, and answer generation grounded on retrieved subgraphs. A key contribution is the design of a synthetic data generation procedure that produces realistic police reports from a limited set of original documents, preserving privacy while supporting both knowledge base construction and benchmark creation. The system is evaluated through controlled experiments on answer quality, grounding, and explainability, and is compared with a baseline RAG pipeline. The results show that the KAG-based approach improves the reliability and traceability of generated answers, providing a generalizable architecture for knowledge-grounded question answering in complex information-intensive domains.

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