Towards Bridged Vision and Language: Learning Cross-Modal Knowledge Representation for Relation Extraction

In natural language processing, relation extraction (RE) is to detect and classify the semantic relationship of two given entities within a sentence. Previous RE methods consider only the textual contents and suffer performance decline in social media when texts lack contexts. Incorporating text-related visual information can supplement the missing semantics for relation extraction in social media posts. However, textual relations are usually abstract and of high-level semantics, which causes the semantic gap between visual contents and textual expressions. In this paper, we propose RECK - a neural network for relation extraction with cross-modal knowledge representations. Different from previous multimodal methods training a common subspace for all modalities, we bridge the semantic gaps by explicitly selecting knowledge paths from external knowledge through the cross-modal object-entity pairs. We further extend the paths into a knowledge graph, and adopt a graph attention network to capture the multi-grained relevant concepts which can provide higher level and key semantics information from external knowledge. Besides, we employ a cross-modal attention mechanism to align and fuse the multimodal information. Experimental results on a multimodal RE dataset show that our model achieves new state-of-the-art performance with knowledge evidence.