Hamed Zamani


2022

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Predicting Prerequisite Relations for Unseen Concepts
Yaxin Zhu | Hamed Zamani
Proceedings of the 2022 Conference on Empirical Methods in Natural Language Processing

Concept prerequisite learning (CPL) plays a key role in developing technologies that assist people to learn a new complex topic or concept. Previous work commonly assumes that all concepts are given at training time and solely focuses on predicting the unseen prerequisite relationships between them. However, many real-world scenarios deal with concepts that are left undiscovered at training time, which is relatively unexplored. This paper studies this problem and proposes a novel alternating knowledge distillation approach to take advantage of both content- and graph-based models for this task. Extensive experiments on three public benchmarks demonstrate up to 10% improvements in terms of F1 score.

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You can’t pick your neighbors, or can you? When and How to Rely on Retrieval in the kNN-LM
Andrew Drozdov | Shufan Wang | Razieh Rahimi | Andrew McCallum | Hamed Zamani | Mohit Iyyer
Findings of the Association for Computational Linguistics: EMNLP 2022

Retrieval-enhanced language models (LMs), which condition their predictions on text retrieved from large external datastores, have recently shown significant perplexity improvements compared to standard LMs. One such approach, the kNN-LM, interpolates any existing LM’s predictions with the output of a k-nearest neighbors model and requires no additional training. In this paper, we explore the importance of lexical and semantic matching in the context of items retrieved by kNN-LM. We find two trends: (1) the presence of large overlapping n-grams between the datastore and evaluation set plays an important factor in strong performance, even when the datastore is derived from the training data; and (2) the kNN-LM is most beneficial when retrieved items have high semantic similarity with the query. Based on our analysis, we define a new formulation of the kNN-LM that uses retrieval quality to assign the interpolation coefficient. We empirically measure the effectiveness of our approach on two English language modeling datasets, Wikitext-103 and PG-19. Our re-formulation of the kNN-LM is beneficial in both cases, and leads to nearly 4% improvement in perplexity on the Wikitext-103 test set.

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DISAPERE: A Dataset for Discourse Structure in Peer Review Discussions
Neha Kennard | Tim O’Gorman | Rajarshi Das | Akshay Sharma | Chhandak Bagchi | Matthew Clinton | Pranay Kumar Yelugam | Hamed Zamani | Andrew McCallum
Proceedings of the 2022 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies

At the foundation of scientific evaluation is the labor-intensive process of peer review. This critical task requires participants to consume vast amounts of highly technical text. Prior work has annotated different aspects of review argumentation, but discourse relations between reviews and rebuttals have yet to be examined. We present DISAPERE, a labeled dataset of 20k sentences contained in 506 review-rebuttal pairs in English, annotated by experts. DISAPERE synthesizes label sets from prior work and extends them to include fine-grained annotation of the rebuttal sentences, characterizing their context in the review and the authors’ stance towards review arguments. Further, we annotate every review and rebuttal sentence. We show that discourse cues from rebuttals can shed light on the quality and interpretation of reviews. Further, an understanding of the argumentative strategies employed by the reviewers and authors provides useful signal for area chairs and other decision makers.

2019

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Multi-step Entity-centric Information Retrieval for Multi-Hop Question Answering
Rajarshi Das | Ameya Godbole | Dilip Kavarthapu | Zhiyu Gong | Abhishek Singhal | Mo Yu | Xiaoxiao Guo | Tian Gao | Hamed Zamani | Manzil Zaheer | Andrew McCallum
Proceedings of the 2nd Workshop on Machine Reading for Question Answering

Multi-hop question answering (QA) requires an information retrieval (IR) system that can find multiple supporting evidence needed to answer the question, making the retrieval process very challenging. This paper introduces an IR technique that uses information of entities present in the initially retrieved evidence to learn to ‘hop’ to other relevant evidence. In a setting, with more than 5 million Wikipedia paragraphs, our approach leads to significant boost in retrieval performance. The retrieved evidence also increased the performance of an existing QA model (without any training) on the benchmark by 10.59 F1.

2015

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Multitask Learning for Adaptive Quality Estimation of Automatically Transcribed Utterances
José G. C. de Souza | Hamed Zamani | Matteo Negri | Marco Turchi | Daniele Falavigna
Proceedings of the 2015 Conference of the North American Chapter of the Association for Computational Linguistics: Human Language Technologies