Michael J. Witbrock

Also published as: Michael Witbrock


2022

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AbductionRules: Training Transformers to Explain Unexpected Inputs
Nathan Young | Qiming Bao | Joshua Bensemann | Michael Witbrock
Findings of the Association for Computational Linguistics: ACL 2022

Transformers have recently been shown to be capable of reliably performing logical reasoning over facts and rules expressed in natural language, but abductive reasoning - inference to the best explanation of an unexpected observation - has been underexplored despite significant applications to scientific discovery, common-sense reasoning, and model interpretability.This paper presents AbductionRules, a group of natural language datasets designed to train and test generalisable abduction over natural-language knowledge bases.We use these datasets to finetune pretrained Transformers and discuss their performance, finding that our models learned generalisable abductive techniques but also learned to exploit the structure of our data.Finally, we discuss the viability of this approach to abductive reasoning and ways in which it may be improved in future work.

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TaKG: A New Dataset for Paragraph-level Table-to-Text Generation Enhanced with Knowledge Graphs
Qianqian Qi | Zhenyun Deng | Yonghua Zhu | Lia Jisoo Lee | Michael Witbrock | Jiamou Liu
Findings of the Association for Computational Linguistics: AACL-IJCNLP 2022

We introduce TaKG, a new table-to-text generation dataset with the following highlights: (1) TaKG defines a long-text (paragraph-level) generation task as opposed to well-established short-text (sentence-level) generation datasets. (2) TaKG is the first large-scale dataset for this task, containing three application domains and ~750,000 samples. (3) To address the divergence phenomenon, TaKG enhances table input using external knowledge graphs, extracted by a new Wikidata-based method. We then propose a new Transformer-based multimodal sequence-to-sequence architecture for TaKG that integrates two pretrained language models RoBERTa and GPT-2. Our model shows reliable performance on long-text generation across a variety of metrics, and outperforms existing models for short-text generation tasks.

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Prompt-based Conservation Learning for Multi-hop Question Answering
Zhenyun Deng | Yonghua Zhu | Yang Chen | Qianqian Qi | Michael Witbrock | Patricia Riddle
Proceedings of the 29th International Conference on Computational Linguistics

Multi-hop question answering (QA) requires reasoning over multiple documents to answer a complex question and provide interpretable supporting evidence. However, providing supporting evidence is not enough to demonstrate that a model has performed the desired reasoning to reach the correct answer. Most existing multi-hop QA methods fail to answer a large fraction of sub-questions, even if their parent questions are answered correctly. In this paper, we propose the Prompt-based Conservation Learning (PCL) framework for multi-hop QA, which acquires new knowledge from multi-hop QA tasks while conserving old knowledge learned on single-hop QA tasks, mitigating forgetting. Specifically, we first train a model on existing single-hop QA tasks, and then freeze this model and expand it by allocating additional sub-networks for the multi-hop QA task. Moreover, to condition pre-trained language models to stimulate the kind of reasoning required for specific multi-hop questions, we learn soft prompts for the novel sub-networks to perform type-specific reasoning. Experimental results on the HotpotQA benchmark show that PCL is competitive for multi-hop QA and retains good performance on the corresponding single-hop sub-questions, demonstrating the efficacy of PCL in mitigating knowledge loss by forgetting.

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Explicit Graph Reasoning Fusing Knowledge and Contextual Information for Multi-hop Question Answering
Zhenyun Deng | Yonghua Zhu | Qianqian Qi | Michael Witbrock | Patricia Riddle
Proceedings of the 2nd Workshop on Deep Learning on Graphs for Natural Language Processing (DLG4NLP 2022)

Current graph-neural-network-based (GNN-based) approaches to multi-hop questions integrate clues from scattered paragraphs in an entity graph, achieving implicit reasoning by synchronous update of graph node representations using information from neighbours; this is poorly suited for explaining how clues are passed through the graph in hops. In this paper, we describe a structured Knowledge and contextual Information Fusion GNN (KIFGraph) whose explicit multi-hop graph reasoning mimics human step by step reasoning. Specifically, we first integrate clues at multiple levels of granularity (question, paragraph, sentence, entity) as nodes in the graph, connected by edges derived using structured semantic knowledge, then use a contextual encoder to obtain the initial node representations, followed by step-by-step two-stage graph reasoning that asynchronously updates node representations. Each node can be related to its neighbour nodes through fused structured knowledge and contextual information, reliably integrating their answer clues. Moreover, a masked attention mechanism (MAM) filters out noisy or redundant nodes and edges, to avoid ineffective clue propagation in graph reasoning. Experimental results show performance competitive with published models on the HotpotQA dataset.

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Eye Gaze and Self-attention: How Humans and Transformers Attend Words in Sentences
Joshua Bensemann | Alex Peng | Diana Benavides-Prado | Yang Chen | Neset Tan | Paul Michael Corballis | Patricia Riddle | Michael Witbrock
Proceedings of the Workshop on Cognitive Modeling and Computational Linguistics

Attention describes cognitive processes that are important to many human phenomena including reading. The term is also used to describe the way in which transformer neural networks perform natural language processing. While attention appears to be very different under these two contexts, this paper presents an analysis of the correlations between transformer attention and overt human attention during reading tasks. An extensive analysis of human eye tracking datasets showed that the dwell times of human eye movements were strongly correlated with the attention patterns occurring in the early layers of pre-trained transformers such as BERT. Additionally, the strength of a correlation was not related to the number of parameters within a transformer. This suggests that something about the transformers’ architecture determined how closely the two measures were correlated.

2020

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Convolutional and Recurrent Neural Networks for Spoken Emotion Recognition
Aaron Keesing | Ian Watson | Michael Witbrock
Proceedings of the The 18th Annual Workshop of the Australasian Language Technology Association

We test four models proposed in the speech emotion recognition (SER) literature on 15 public and academic licensed datasets in speaker-independent cross-validation. Results indicate differences in the performance of the models which is partly dependent on the dataset and features used. We also show that a standard utterance-level feature set still performs competitively with neural models on some datasets. This work serves as a starting point for future model comparisons, in addition to open-sourcing the testing code.

2019

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Graph Enhanced Cross-Domain Text-to-SQL Generation
Siyu Huo | Tengfei Ma | Jie Chen | Maria Chang | Lingfei Wu | Michael Witbrock
Proceedings of the Thirteenth Workshop on Graph-Based Methods for Natural Language Processing (TextGraphs-13)

Semantic parsing is a fundamental problem in natural language understanding, as it involves the mapping of natural language to structured forms such as executable queries or logic-like knowledge representations. Existing deep learning approaches for semantic parsing have shown promise on a variety of benchmark data sets, particularly on text-to-SQL parsing. However, most text-to-SQL parsers do not generalize to unseen data sets in different domains. In this paper, we propose a new cross-domain learning scheme to perform text-to-SQL translation and demonstrate its use on Spider, a large-scale cross-domain text-to-SQL data set. We improve upon a state-of-the-art Spider model, SyntaxSQLNet, by constructing a graph of column names for all databases and using graph neural networks to compute their embeddings. The resulting embeddings offer better cross-domain representations and SQL queries, as evidenced by substantial improvement on the Spider data set compared to SyntaxSQLNet.

2018

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A Systematic Classification of Knowledge, Reasoning, and Context within the ARC Dataset
Michael Boratko | Harshit Padigela | Divyendra Mikkilineni | Pritish Yuvraj | Rajarshi Das | Andrew McCallum | Maria Chang | Achille Fokoue-Nkoutche | Pavan Kapanipathi | Nicholas Mattei | Ryan Musa | Kartik Talamadupula | Michael Witbrock
Proceedings of the Workshop on Machine Reading for Question Answering

The recent work of Clark et al. (2018) introduces the AI2 Reasoning Challenge (ARC) and the associated ARC dataset that partitions open domain, complex science questions into easy and challenge sets. That paper includes an analysis of 100 questions with respect to the types of knowledge and reasoning required to answer them; however, it does not include clear definitions of these types, nor does it offer information about the quality of the labels. We propose a comprehensive set of definitions of knowledge and reasoning types necessary for answering the questions in the ARC dataset. Using ten annotators and a sophisticated annotation interface, we analyze the distribution of labels across the challenge set and statistics related to them. Additionally, we demonstrate that although naive information retrieval methods return sentences that are irrelevant to answering the query, sufficient supporting text is often present in the (ARC) corpus. Evaluating with human-selected relevant sentences improves the performance of a neural machine comprehension model by 42 points.

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Word Mover’s Embedding: From Word2Vec to Document Embedding
Lingfei Wu | Ian En-Hsu Yen | Kun Xu | Fangli Xu | Avinash Balakrishnan | Pin-Yu Chen | Pradeep Ravikumar | Michael J. Witbrock
Proceedings of the 2018 Conference on Empirical Methods in Natural Language Processing

While the celebrated Word2Vec technique yields semantically rich representations for individual words, there has been relatively less success in extending to generate unsupervised sentences or documents embeddings. Recent work has demonstrated that a distance measure between documents called Word Mover’s Distance (WMD) that aligns semantically similar words, yields unprecedented KNN classification accuracy. However, WMD is expensive to compute, and it is hard to extend its use beyond a KNN classifier. In this paper, we propose the Word Mover’s Embedding (WME), a novel approach to building an unsupervised document (sentence) embedding from pre-trained word embeddings. In our experiments on 9 benchmark text classification datasets and 22 textual similarity tasks, the proposed technique consistently matches or outperforms state-of-the-art techniques, with significantly higher accuracy on problems of short length.

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An Interface for Annotating Science Questions
Michael Boratko | Harshit Padigela | Divyendra Mikkilineni | Pritish Yuvraj | Rajarshi Das | Andrew McCallum | Maria Chang | Achille Fokoue | Pavan Kapanipathi | Nicholas Mattei | Ryan Musa | Kartik Talamadupula | Michael Witbrock
Proceedings of the 2018 Conference on Empirical Methods in Natural Language Processing: System Demonstrations

Recent work introduces the AI2 Reasoning Challenge (ARC) and the associated ARC dataset that partitions open domain, complex science questions into an Easy Set and a Challenge Set. That work includes an analysis of 100 questions with respect to the types of knowledge and reasoning required to answer them. However, it does not include clear definitions of these types, nor does it offer information about the quality of the labels or the annotation process used. In this paper, we introduce a novel interface for human annotation of science question-answer pairs with their respective knowledge and reasoning types, in order that the classification of new questions may be improved. We build on the classification schema proposed by prior work on the ARC dataset, and evaluate the effectiveness of our interface with a preliminary study involving 10 participants.

2009

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Building Conversational Agents with Basilica
Rohit Kumar | Carolyn P. Rosé | Michael J. Witbrock
Proceedings of Human Language Technologies: The 2009 Annual Conference of the North American Chapter of the Association for Computational Linguistics, Companion Volume: Demonstration Session

2004

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Inferring parts of speech for lexical mappings via the Cyc KB
Tom O’Hara | Stefano Bertolo | Michael Witbrock | Bjørn Aldag | Jon Curtis | Kathy Panton | Dave Schneider | Nancy Salay
COLING 2004: Proceedings of the 20th International Conference on Computational Linguistics

2000

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Headline Generation Based on Statistical Translation
Michele Banko | Vibhu O. Mittal | Michael J. Witbrock
Proceedings of the 38th Annual Meeting of the Association for Computational Linguistics