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摘要:
知识图谱问答(KGQA)是给定自然语言问题,对问题进行语义理解和解析,进而利用知识图谱进行查询、推理得出答案的过程。但知识图谱通常是不完整的,链接缺失给多跳问答带来许多挑战。许多方法在利用知识图谱嵌入时忽略了重要的路径信息来评估路径和多关系问题之间的相关性;且使用文本语料库也会限制文本增强模型的可扩展性。针对这些现有方法的缺陷,提出了基于变形图匹配的知识图谱问答(DGM-KGQA)模型,该模型同时利用问题和主题实体构建语义子图,与知识图谱的局部结构匹配并找到正确答案。在基准数据集MetaQA上的实验结果验证了DGM-KGQA的有效性,该模型在完整知识图谱上检索到的答案准确率分别比PullNet、EmbedKGQA增加了4.2%、0.8%;在完整度仅有一半的知识图谱上检索到的答案准确率分别比PullNet、EmbedKGQA增加了11.1%、0.5%。实验证明提出的变形图匹配模型能够有效地增强知识图谱的关联性及多跳问答的答案准确率。
Abstract:Knowledge Graph Question Answering (KGQA) is a process in which a given natural language question is semantically understood and parsed, and then the knowledge graph is used to query and reason to get the answer. But knowledge graphs which lack links, bring many challenges to multi-hop question answering. Many methods ignore important path information to evaluate the correlation between paths and multi-relationship problems when using knowledge graph embeddings, and text corpora also limit the scalability of text-enhanced models. Due to the drawbacks of these existing approaches, the Multi-hop Knowledge Graph Question Answering Based on Deformed Graph Matching (DGM-KGQA) method is proposed. This method builds semantic subgraphs using both question and topic entities, which then match the local structure of the knowledge graph to determine the correct solution. The experimental results on the benchmark dataset MetaQA verify the effectiveness of DGM-KGQA. In comparison to PullNet and EmbedKGQA, the accuracy of the answers retrieved on the completed knowledge graph is 4.2% higher than that of PullNet and 0.8% higher than that of EmbedKGQA. The accuracy of the answers retrieved on half of the knowledge graphs is 11.1% higher than that of PullNet and 0.5% higher than that of EmbedKGQA. Experiments show that the proposed deformed graph matching model can effectively enhance the relevance of knowledge graphs and the answer accuracy of multi-hop question answering.
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表 1 MetaQA数据集中不同跳数的问答对数量
Table 1. The number of question answering pairs with different hops in MetaQA dataset
MetaQA 训练集 验证集 测试集 1-hop 96 106 9 992 9 947 2-hop 118 948 14 872 14 872 3-hop 114 196 14 274 14 274 表 2 MetaQA数据集不同完整度的实验结果
Table 2. Experimental results for MetaQA datasets with different degrees of completeness
模型 总体性能 KG-Full KG-Half GraftNet 89.1 57.9 PullNet 96.1 58.2 KV-Mem 74.0 45.8 EmbedKGQA 97.0 81.9 DGM-KGQA 98.2 90.0 表 3 完整和不完整知识图谱中不同跳数的总体性能
Table 3. Overall performance of different hops in complete and incomplete knowledge graphs
模型 KG-Full KG-Half 1-hop 2-hop 3-hop 1-hop 2-hop 3-hop GraftNet 97.0 94.8 77.7 64.0 52.6 59.2 PullNet 97.0 99.9 91.4 65.1 52.1 59.7 KV-Mem 96.2 82.7 48.9 63.6 41.8 37.6 EmbedKGQA 97.5 98.8 94.8 83.9 91.8 70.3 DGM-KGQA 97.2 98.4 95.6 78.3 92.5 70.8 表 4 本文模型的消融实验结果
Table 4. The ablation results of the model in this paper
Import 总体性能 KG-Full KG-Half 1-hop 2-hop 3-hop 1-hop 2-hop 3-hop -local matching 86.4 90.3 85.2 59.8 53.5 54.3 -Overall puzzle 93.2 95.7 91.5 72.4 85.8 64.5 DGM-KGQA(final) 97.2 98.4 95.6 78.3 92.5 70.8 注:-local matching, -Overall puzzle中的-为消融实验去掉该模块后的结果。 -
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