Multi-granularity Complex Question Answering Over Temporal Knowledge Graphs
摘要
Temporal knowledge graph question answering (TKGQA), which utilizes temporal knowledge graphs (TKGs) to answer natural language questions, has attracted increasing attention in recent years. Real-life applications of TKGQA tend to be complex in temporal granularity, i.e., the questions may concern mixed temporal granularities (e.g., both day and month). Nevertheless, multi-granularity temporal knowledge graph question answering (Multi-granularity TKGQA) remains underexplored. Existing methods are mainly designed for simple multi-granularity temporal questions that can be answered by a single TKG fact, struggling with multi-granularity temporal questions requiring multi-fact reasoning and implicit temporal inference. This paper proposes a comprehensive embedding-based framework for multi-granularity complex TKGQA, namely MCTQA, which consists of three core modules. First, a question representation module encodes the question into semantic embeddings. Second, a graph structure-aware module incorporates TKG structural information to support multi-fact reasoning by treating entities in question as “bridges”. Third, a multi-granularity temporal fusion module identifies implicit temporal signals in the question and enhances the question representation by generating granularity-specific time embeddings using a novel time anchor-based time embedding generation method. Experimental results prove that MCTQA significantly outperforms strong baselines on the challenging MULTITQ dataset, achieving an absolute improvement of up to 6% in overall Hits@1. The code is available at https://github.com/Leserein-yjh/MCTQA .