Improving Complex Knowledge Base Question Answering with Relation-Aware Subgraph Retrieval and Reasoning Network.

Complex Knowledge Base Question Answering aims to answer a complex question over a Knowledge Base. A mainstream solution is based on information retrieval, which usually extracts a pivotal subgraph from entire Knowledge Base to locate candidate answers, and then determines the plausible answers with semantic matching between candidate answers and the question. However, such a paradigm can have two critical problems: 1) Complex Knowledge Base Question Answering can be sensitive to the subgraph, since a small subgraph may exclude the answers, while a large one may introduce a lot of noise; 2) directly deriving answers with semantic matching neglects the global topology in the Knowledge Base, which may limit the capability in answer reasoning. To tackle above challenges, we propose the Relation-Aware Subgraph Retrieval and Reasoning Network, where relations are emphasized to construct subgraphs and answer reasoning. Specifically, we present a Relation-Aware Subgraph Retrieval (RASR) method to initialize and prune subgraphs with the guidance of relation semantics. To comprehensively understand the complex correlations between the question and candidate answers, we put forward a Relation-Aware Reasoning Network (RARN), which contains a text reasoning module focusing on the semantics understanding of the question and a graph reasoning module focusing on mining the topology between the topic entities and the answers. Experiments on two classical benchmark datasets show that our reasoning model outperforms the state-of-the-art results of Information Retrieval models. What's more, data statistical analysis on the subgraphs demonstrates the effectiveness of our proposed subgraph retrieval method.