DIRECT: Directional Relevance in Conversational Trajectories
Paper · 2026 · Anshuman Mourya, Rajdeep Mukherjee, Prerna Jolly et al.
Summary
Users of conversational assistants frequently struggle with opening a dialogue or deciding which question to pose next. This Amazon industry paper treats Next Question Suggestion (NQS) as a fast retrieval task rather than LLM generation. Generation is costly, slow, and can produce unsafe or unanswerable questions, so DIRECT instead selects candidates from a pre-built Question Bank.
The key difficulty is directionality. A good suggestion should be related to the query but not a paraphrase of it, and it should move the dialogue forward rather than ask about background information (a "prior"). DIRECT addresses this in three steps:
- domain-adaptive MLM pre-training,
- a dual-encoder retriever fine-tuned hierarchically so that relevant pairs fall between similar and irrelevant ones in similarity,
- a cross-encoder re-ranker trained to tell follow-ups from priors.
The system is evaluated on a proprietary dataset and on FQ-Bank. An LLM judge estimates click-through rate. DIRECT beats an off-the-shelf BGE-Large retriever while staying well within a 1-second latency budget. This makes it a practical recipe for low-latency suggestion features in commercial assistants.
Key points
- Query–suggestion pairs fall into four categories: similar, follow-up, prior, and irrelevant. Only follow-ups should be shown to users, and priors serve as hard negatives for the re-ranker.
- Pre-training uses NER-guided masking: function words are filtered out, and 25% of the remaining domain-specific tokens are masked.
- Hierarchical fine-tuning improves Precision@Recall on the 3-way task by up to 0.08 on the proprietary data and up to 0.16 on FQ-Bank. On follow-up vs. prior detection, the gains are up to 0.12 and 0.1.
- In the Claude Sonnet 4.5 LLM-as-a-judge evaluation, predicted CTR rises 4% without the re-ranker and 6% with it, relative to vanilla BGE-Large. p90 latency is roughly 1.3 ms and 27 ms respectively; this pairing is inferred from Table 5, whose layout was garbled in extraction.
- Limitations: the system has not yet been deployed to production, depends on annotated data, and was tested on English only.
Institutions
Fields, topics and concepts
📚 Shelves 4The field of science this work belongs to (OpenAlex fields).Computer Science · 16,667 worksArtificial Intelligence · 16,194 worksArts and Humanities · 16,039 worksLanguage and Linguistics · 15,891 works
🧭 Topics 1Research subjects and languages the work is about.Dialogue systems · 624 works
Cite
Cite as Anshuman Mourya, Rajdeep Mukherjee, Prerna Jolly, Vinayak S Puranik and Sivaramakrishnan R Kaveri. 2026. DIRECT: Directional Relevance in Conversational Trajectories. Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 5: Industry Track).
@inproceedings{mourya2026direct,
title = {{DIRECT: Directional Relevance in Conversational Trajectories}},
author = {Anshuman Mourya, Rajdeep Mukherjee, Prerna Jolly, Vinayak S Puranik and Sivaramakrishnan R Kaveri},
booktitle = {Proceedings of the 19th Conference of the European Chapter of the Association for Computational Linguistics (Volume 5: Industry Track)},
year = {2026},
doi = {10.18653/v1/2026.eacl-industry.71},
url = {https://doi.org/10.18653/v1/2026.eacl-industry.71}
}References
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