TUTA1 at the NTCIR-10 Intent Task

In NTCIR-10, we participated in the subtask of Subtopic Mining. We classify test topics into two types: role-explicit topic and roleimplicit topic. According to the topic type, we devise different approaches to perform subtopic mining. Specifically, for roleexplicit topics, we propose an approach of modifier graph based subtopic mining. The key idea is that: The modifier graph corresponding to a role-explicit topic is decomposable into clusters with strong intra-cluster interaction and relatively weak inter-cluster interaction. Each modifier cluster intuitively reveals a possible subtopic. For role-implicit topics that generally express single information needs, we directly generate the ranked list through semantic similarities leveraging on lexical ontologies. The evaluation results show that our best Chinese subtopic mining run gets the first position among all the runs in terms of # D nDCG . However, our English subtopic mining runs show a poor performance, which is planned to be further improved in our future work.