MTGER: Multi-view Temporal Graph Enhanced Temporal Reasoning over
  Time-Involved Document
Zheng Chu Zekun Wang Jiafeng Liang Ming Liu Bing Qin
The facts and time in the document are intricately intertwined, making
temporal reasoning over documents challenging. Previous work models time
implicitly, making it difficult to handle such complex relationships. To
address this issue, we propose MTGER, a novel Multi-view Temporal Graph
Enhanced Temporal Reasoning framework for temporal reasoning over time-involved
documents. Concretely, MTGER explicitly models the temporal relationships among
facts by multi-view temporal graphs. On the one hand, the heterogeneous
temporal graphs explicitly model the temporal and discourse relationships among
facts; on the other hand, the multi-view mechanism captures both time-focused
and fact-focused information, allowing the two views to complement each other
through adaptive fusion. To further improve the implicit reasoning capability
of the model, we design a self-supervised time-comparing objective. Extensive
experimental results demonstrate the effectiveness of our method on the TimeQA
and SituatedQA datasets. Furthermore, MTGER gives more consistent answers under
question perturbations.