Multilingual question answering tasks typically assume answers exist in the same language as the question. Yet in practice, many languages face both information scarcity---where languages have few reference articles---and information asymmetry---where questions reference concepts from other cultures. This work extends open-retrieval question answering to a cross-lingual setting enabling questions from one language to be answered via answer content from another language. We construct a large-scale dataset built on questions from TyDi QA lacking same-language answers. Our task formulation, called Cross-lingual Open Retrieval Question Answering (XOR QA), includes 40k information-seeking questions from across 7 diverse non-English languages. Based on this dataset, we introduce three new tasks that involve cross-lingual document retrieval using multi-lingual and English resources. We establish baselines with state-of-the-art machine translation systems and cross-lingual pretrained models. Experimental results suggest that XOR QA is a challenging task that will facilitate the development of novel techniques for multilingual question answering. Our data and code are available at https://nlp.cs.washington.edu/xorqa.

通过使用跨语言开放检索问题回答，扩展多语言问答任务，解决信息匮乏和信息不对称问题。在 TyDi QA 上构建了一个大规模数据集，并建立了三个跨语言文档检索任务的基线。利用机器翻译系统和跨语言预训练模型，在实验中得出 XOR QA 是一个具有挑战性的任务，将促进多语言问答技术的开发。

XOR QA：跨语言开放检索问答