Making Information Seeking Easier: An Improved Pipeline for Conversational Search

Vaibhav Kumar, Jamie Callan


Abstract
This paper presents a highly effective pipeline for passage retrieval in a conversational search setting. The pipeline comprises of two components: Conversational Term Selection (CTS) and Multi-View Reranking (MVR). CTS is responsible for performing the first-stage of passage retrieval. Given an input question, it uses a BERT-based classifier (trained with weak supervision) to de-contextualize the input by selecting relevant terms from the dialog history. Using the question and the selected terms, it issues a query to a search engine to perform the first-stage of passage retrieval. On the other hand, MVR is responsible for contextualized passage reranking. It first constructs multiple views of the information need embedded within an input question. The views are based on the dialog history and the top documents obtained in the first-stage of retrieval. It then uses each view to rerank passages using BERT (fine-tuned for passage ranking). Finally, MVR performs a fusion over the rankings produced by the individual views. Experiments show that the above combination improves first-state retrieval as well as the overall accuracy in a reranking pipeline. On the key metric of NDCG@3, the proposed combination achieves a relative performance improvement of 14.8% over the state-of-the-art baseline and is also able to surpass the Oracle.
Anthology ID:
2020.findings-emnlp.354
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2020
Month:
November
Year:
2020
Address:
Online
Editors:
Trevor Cohn, Yulan He, Yang Liu
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
3971–3980
Language:
URL:
https://aclanthology.org/2020.findings-emnlp.354
DOI:
10.18653/v1/2020.findings-emnlp.354
Bibkey:
Cite (ACL):
Vaibhav Kumar and Jamie Callan. 2020. Making Information Seeking Easier: An Improved Pipeline for Conversational Search. In Findings of the Association for Computational Linguistics: EMNLP 2020, pages 3971–3980, Online. Association for Computational Linguistics.
Cite (Informal):
Making Information Seeking Easier: An Improved Pipeline for Conversational Search (Kumar & Callan, Findings 2020)
Copy Citation:
PDF:
https://aclanthology.org/2020.findings-emnlp.354.pdf
Video:
 https://slideslive.com/38940710