Matthew Henderson


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ConVEx: Data-Efficient and Few-Shot Slot Labeling
Matthew Henderson | Ivan Vulić
Proceedings of the 2021 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies

We propose ConVEx (Conversational Value Extractor), an efficient pretraining and fine-tuning neural approach for slot-labeling dialog tasks. Instead of relying on more general pretraining objectives from prior work (e.g., language modeling, response selection), ConVEx’s pretraining objective, a novel pairwise cloze task using Reddit data, is well aligned with its intended usage on sequence labeling tasks. This enables learning domain-specific slot labelers by simply fine-tuning decoding layers of the pretrained general-purpose sequence labeling model, while the majority of the pretrained model’s parameters are kept frozen. We report state-of-the-art performance of ConVEx across a range of diverse domains and data sets for dialog slot-labeling, with the largest gains in the most challenging, few-shot setups. We believe that ConVEx’s reduced pretraining times (i.e., only 18 hours on 12 GPUs) and cost, along with its efficient fine-tuning and strong performance, promise wider portability and scalability for data-efficient sequence-labeling tasks in general.


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ConveRT: Efficient and Accurate Conversational Representations from Transformers
Matthew Henderson | Iñigo Casanueva | Nikola Mrkšić | Pei-Hao Su | Tsung-Hsien Wen | Ivan Vulić
Findings of the Association for Computational Linguistics: EMNLP 2020

General-purpose pretrained sentence encoders such as BERT are not ideal for real-world conversational AI applications; they are computationally heavy, slow, and expensive to train. We propose ConveRT (Conversational Representations from Transformers), a pretraining framework for conversational tasks satisfying all the following requirements: it is effective, affordable, and quick to train. We pretrain using a retrieval-based response selection task, effectively leveraging quantization and subword-level parameterization in the dual encoder to build a lightweight memory- and energy-efficient model. We show that ConveRT achieves state-of-the-art performance across widely established response selection tasks. We also demonstrate that the use of extended dialog history as context yields further performance gains. Finally, we show that pretrained representations from the proposed encoder can be transferred to the intent classification task, yielding strong results across three diverse data sets. ConveRT trains substantially faster than standard sentence encoders or previous state-of-the-art dual encoders. With its reduced size and superior performance, we believe this model promises wider portability and scalability for Conversational AI applications.

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Span-ConveRT: Few-shot Span Extraction for Dialog with Pretrained Conversational Representations
Samuel Coope | Tyler Farghly | Daniela Gerz | Ivan Vulić | Matthew Henderson
Proceedings of the 58th Annual Meeting of the Association for Computational Linguistics

We introduce Span-ConveRT, a light-weight model for dialog slot-filling which frames the task as a turn-based span extraction task. This formulation allows for a simple integration of conversational knowledge coded in large pretrained conversational models such as ConveRT (Henderson et al., 2019). We show that leveraging such knowledge in Span-ConveRT is especially useful for few-shot learning scenarios: we report consistent gains over 1) a span extractor that trains representations from scratch in the target domain, and 2) a BERT-based span extractor. In order to inspire more work on span extraction for the slot-filling task, we also release RESTAURANTS-8K, a new challenging data set of 8,198 utterances, compiled from actual conversations in the restaurant booking domain.

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Efficient Intent Detection with Dual Sentence Encoders
Iñigo Casanueva | Tadas Temčinas | Daniela Gerz | Matthew Henderson | Ivan Vulić
Proceedings of the 2nd Workshop on Natural Language Processing for Conversational AI

Building conversational systems in new domains and with added functionality requires resource-efficient models that work under low-data regimes (i.e., in few-shot setups). Motivated by these requirements, we introduce intent detection methods backed by pretrained dual sentence encoders such as USE and ConveRT. We demonstrate the usefulness and wide applicability of the proposed intent detectors, showing that: 1) they outperform intent detectors based on fine-tuning the full BERT-Large model or using BERT as a fixed black-box encoder on three diverse intent detection data sets; 2) the gains are especially pronounced in few-shot setups (i.e., with only 10 or 30 annotated examples per intent); 3) our intent detectors can be trained in a matter of minutes on a single CPU; and 4) they are stable across different hyperparameter settings. In hope of facilitating and democratizing research focused on intention detection, we release our code, as well as a new challenging single-domain intent detection dataset comprising 13,083 annotated examples over 77 intents.


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PolyResponse: A Rank-based Approach to Task-Oriented Dialogue with Application in Restaurant Search and Booking
Matthew Henderson | Ivan Vulić | Iñigo Casanueva | Paweł Budzianowski | Daniela Gerz | Sam Coope | Georgios Spithourakis | Tsung-Hsien Wen | Nikola Mrkšić | Pei-Hao Su
Proceedings of the 2019 Conference on Empirical Methods in Natural Language Processing and the 9th International Joint Conference on Natural Language Processing (EMNLP-IJCNLP): System Demonstrations

We present PolyResponse, a conversational search engine that supports task-oriented dialogue. It is a retrieval-based approach that bypasses the complex multi-component design of traditional task-oriented dialogue systems and the use of explicit semantics in the form of task-specific ontologies. The PolyResponse engine is trained on hundreds of millions of examples extracted from real conversations: it learns what responses are appropriate in different conversational contexts. It then ranks a large index of text and visual responses according to their similarity to the given context, and narrows down the list of relevant entities during the multi-turn conversation. We introduce a restaurant search and booking system powered by the PolyResponse engine, currently available in 8 different languages.

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A Repository of Conversational Datasets
Matthew Henderson | Paweł Budzianowski | Iñigo Casanueva | Sam Coope | Daniela Gerz | Girish Kumar | Nikola Mrkšić | Georgios Spithourakis | Pei-Hao Su | Ivan Vulić | Tsung-Hsien Wen
Proceedings of the First Workshop on NLP for Conversational AI

Progress in Machine Learning is often driven by the availability of large datasets, and consistent evaluation metrics for comparing modeling approaches. To this end, we present a repository of conversational datasets consisting of hundreds of millions of examples, and a standardised evaluation procedure for conversational response selection models using 1-of-100 accuracy. The repository contains scripts that allow researchers to reproduce the standard datasets, or to adapt the pre-processing and data filtering steps to their needs. We introduce and evaluate several competitive baselines for conversational response selection, whose implementations are shared in the repository, as well as a neural encoder model that is trained on the entire training set.

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Training Neural Response Selection for Task-Oriented Dialogue Systems
Matthew Henderson | Ivan Vulić | Daniela Gerz | Iñigo Casanueva | Paweł Budzianowski | Sam Coope | Georgios Spithourakis | Tsung-Hsien Wen | Nikola Mrkšić | Pei-Hao Su
Proceedings of the 57th Annual Meeting of the Association for Computational Linguistics

Despite their popularity in the chatbot literature, retrieval-based models have had modest impact on task-oriented dialogue systems, with the main obstacle to their application being the low-data regime of most task-oriented dialogue tasks. Inspired by the recent success of pretraining in language modelling, we propose an effective method for deploying response selection in task-oriented dialogue. To train response selection models for task-oriented dialogue tasks, we propose a novel method which: 1) pretrains the response selection model on large general-domain conversational corpora; and then 2) fine-tunes the pretrained model for the target dialogue domain, relying only on the small in-domain dataset to capture the nuances of the given dialogue domain. Our evaluation on five diverse application domains, ranging from e-commerce to banking, demonstrates the effectiveness of the proposed training method.


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The Second Dialog State Tracking Challenge
Matthew Henderson | Blaise Thomson | Jason D. Williams
Proceedings of the 15th Annual Meeting of the Special Interest Group on Discourse and Dialogue (SIGDIAL)

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Word-Based Dialog State Tracking with Recurrent Neural Networks
Matthew Henderson | Blaise Thomson | Steve Young
Proceedings of the 15th Annual Meeting of the Special Interest Group on Discourse and Dialogue (SIGDIAL)


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POMDP-based dialogue manager adaptation to extended domains
Milica Gašić | Catherine Breslin | Matthew Henderson | Dongho Kim | Martin Szummer | Blaise Thomson | Pirros Tsiakoulis | Steve Young
Proceedings of the SIGDIAL 2013 Conference

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Deep Neural Network Approach for the Dialog State Tracking Challenge
Matthew Henderson | Blaise Thomson | Steve Young
Proceedings of the SIGDIAL 2013 Conference


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The Effect of Cognitive Load on a Statistical Dialogue System
Milica Gašić | Pirros Tsiakoulis | Matthew Henderson | Blaise Thomson | Kai Yu | Eli Tzirkel | Steve Young
Proceedings of the 13th Annual Meeting of the Special Interest Group on Discourse and Dialogue