Formal query building is an important part of complex question answering over knowledge bases. It aims to build correct executable queries for questions. Recent methods try to rank candidate queries generated by a state-transition strategy. However, this candidate generation strategy ignores the structure of queries, resulting in a considerable number of noisy queries. In this paper, we propose a new formal query building approach that consists of two stages. In the first stage, we predict the query structure of the question and leverage the structure to constrain the generation of the candidate queries. We propose a novel graph generation framework to handle the structure prediction task and design an encoder-decoder model to predict the argument of the predetermined operation in each generative step. In the second stage, we follow the previous methods to rank the candidate queries. The experimental results show that our formal query building approach outperforms existing methods on complex questions while staying competitive on simple questions.

本文提出一种新的正式查询构建方法，它包括两个阶段：第一阶段预测问题的查询结构并利用结构约束候选查询的生成；第二阶段按照以前的方法对候选查询进行排名。实验结果表明，我们的正式查询构建方法在复杂问题上表现优异，同时在简单问题上保持一定的竞争力。

针对知识库的复杂问答的正式查询构建与查询结构预测