Graph Representation of Tables+Text and Compact Subgraph Retrieval for QA Tasks

Vishwajeet Kumar, Jaydeep Sen, Bhawna Chelani, Soumen Chakrabarti

Abstract: Large language models (LLMs) are increasingly used for table+text question answering (QA), but there is insufficient focus on unified table and text representation needed for effective retrieval guidance. In response, we present TabSegNet, comprised of (1) a fine-tuned LLM to decompose the question into segments that access individual tables;(2) a unified graph representation of tables+text, where retrieval amounts to identifying a compact node subset collectively covering the question segments; and (3) a novel graph neural network (GNN) whose messages are informed by the question and its segmentation. Experiments with existing and newly-created data sets demonstrate the promise of our approach, compared to sparse and dense nearest neighbor search, or using an LLM for retrieval.