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Yashar Mehdad

24 accepted papers

2025

LLM-Friendly Knowledge Representation for Customer Support

COLING 2025industry

We propose a practical approach by integrating Large Language Models (LLMs) with a framework designed to navigate the complexities of Airbnb customer support operations. In this paper, our methodology employs a novel reformatting technique, the Intent, Context, and Action (ICA) format, which transfo…

Cited by 2SourcePDFScholar
2024

Effective Long-Context Scaling of Foundation Models

NAACL 2024long

We present an effective recipe to train strong long-context LLMs that are capable of utilizing massive context windows of up to 32,000 tokens. Our models are built through continual pretraining from Llama 2 checkpoints with longer text sequences and on a dataset where long texts are upsampled. We pe…

Cited by 231SourcePDFScholar
2024

LLM-QAT: Data-Free Quantization Aware Training for Large Language Models

ACL 2024findings

Several post-training quantization methods have been applied to large language models (LLMs), and have been shown to perform well down to 8-bits. We find that these methods break down at lower bit precision, and investigate quantization-aware training for LLMs (LLM-QAT) to push quantization levels e…

2023

Adapting Pretrained Text-to-Text Models for Long Text Sequences

EMNLP 2023long findings

We present an empirical study of adapting an existing pretrained text-to-text model for long-sequence inputs. Through a comprehensive study along three axes of the pretraining pipeline -- model architecture, optimization objective, and pretraining corpus, we propose an effective recipe to build long…

Cited by 0SourcecodeScholar
2023

CITADEL: Conditional Token Interaction via Dynamic Lexical Routing for Efficient and Effective Multi-Vector Retrieval

ACL 2023long

Multi-vector retrieval methods combine the merits of sparse (e.g. BM25) and dense (e.g. DPR) retrievers and have achieved state-of-the-art performance on various retrieval tasks. These methods, however, are orders of magnitude slower and need much more space to store their indices compared to their…

2023

Hierarchical Video-Moment Retrieval and Step-Captioning

CVPR 2023poster

There is growing interest in searching for information from large video corpora. Prior works have studied relevant tasks, such as text-based video retrieval, moment retrieval, video summarization, and video captioning in isolation, without an end-to-end setup that can jointly search from video corpo…

2023

How to Train Your Dragon: Diverse Augmentation Towards Generalizable Dense Retrieval

EMNLP 2023long findings

Various techniques have been developed in recent years to improve dense retrieval (DR), such as unsupervised contrastive learning and pseudo-query generation. Existing DRs, however, often suffer from effectiveness tradeoffs between supervised and zero-shot retrieval, which some argue was due to the…

Cited by 0SourcecodeScholar
2022

BiT: Robustly Binarized Multi-distilled Transformer

NeurIPS 2022accept

Modern pre-trained transformers have rapidly advanced the state-of-the-art in machine learning, but have also grown in parameters and computational complexity, making them increasingly difficult to deploy in resource-constrained environments. Binarization of the weights and activations of the networ…

2022

Bridging the Training-Inference Gap for Dense Phrase Retrieval

EMNLP 2022finding

Building dense retrievers requires a series of standard procedures, including training and validating neural models and creating indexes for efficient search. However, these procedures are often misaligned in that training objectives do not exactly reflect the retrieval scenario at inference time. I…

Cited by 2SourcePDFScholar
2022

CONFIT: Toward Faithful Dialogue Summarization with Linguistically-Informed Contrastive Fine-tuning

NAACL 2022long

Factual inconsistencies in generated summaries severely limit the practical applications of abstractive dialogue summarization. Although significant progress has been achieved by using pre-trained neural language models, substantial amounts of hallucinated content are found during the human evaluati…

Cited by 71SourcePDFScholar
2022

Domain-matched Pre-training Tasks for Dense Retrieval

NAACL 2022findings

Pre-training on larger datasets with ever increasing model size isnow a proven recipe for increased performance across almost all NLP tasks.A notable exception is information retrieval, where additional pre-traininghas so far failed to produce convincing results. We show that, with theright pre-trai…

2022

Investigating Crowdsourcing Protocols for Evaluating the Factual Consistency of Summaries

NAACL 2022long

Current pre-trained models applied for summarization are prone to factual inconsistencies that misrepresent the source text. Evaluating the factual consistency of summaries is thus necessary to develop better models. However, the human evaluation setup for evaluating factual consistency has not been…

Cited by 20SourcePDFScholar
2022

STRUDEL: Structured Dialogue Summarization for Dialogue Comprehension

EMNLP 2022main

Abstractive dialogue summarization has long been viewed as an important standalone task in natural language processing, but no previous work has explored the possibility of whether abstractive dialogue summarization can also be used as a means to boost an NLP system’s performance on other important…

Cited by 2SourcePDFScholar
2022

Salient Phrase Aware Dense Retrieval: Can a Dense Retriever Imitate a Sparse One?

EMNLP 2022finding

Despite their recent popularity and well-known advantages, dense retrievers still lag behind sparse methods such as BM25 in their ability to reliably match salient phrases and rare entities in the query and to generalize to out-of-domain data. It has been argued that this is an inherent limitation o…

2022

Simple Local Attentions Remain Competitive for Long-Context Tasks

NAACL 2022long

Many NLP tasks require processing long contexts beyond the length limit of pretrained models. In order to scale these models to longer text sequences, many efficient long-range attention variants have been proposed. Despite the abundance of research along this direction, it is still difficult to gau…

2022

UniK-QA: Unified Representations of Structured and Unstructured Knowledge for Open-Domain Question Answering

NAACL 2022findings

We study open-domain question answering with structured, unstructured and semi-structured knowledge sources, including text, tables, lists and knowledge bases. Departing from prior work, we propose a unifying approach that homogenizes all sources by reducing them to text and applies the retriever-re…

2021

Answering Complex Open-Domain Questions with Multi-Hop Dense Retrieval

ICLR 2021poster

We propose a simple and efficient multi-hop dense retrieval approach for answering complex open-domain questions, which achieves state-of-the-art performance on two multi-hop datasets, HotpotQA and multi-evidence FEVER. Contrary to previous work, our method does not require access to any corpus-spec…

2021

ConvoSumm: Conversation Summarization Benchmark and Improved Abstractive Summarization with Argument Mining

ACL 2021long

While online conversations can cover a vast amount of information in many different formats, abstractive text summarization has primarily focused on modeling solely news articles. This research gap is due, in part, to the lack of standardized datasets for summarizing online discussions. To address t…

2021

FiD-Ex: Improving Sequence-to-Sequence Models for Extractive Rationale Generation

EMNLP 2021main

Natural language (NL) explanations of model predictions are gaining popularity as a means to understand and verify decisions made by large black-box pre-trained models, for tasks such as Question Answering (QA) and Fact Verification. Recently, pre-trained sequence to sequence (seq2seq) models have p…

2021

Improving Zero and Few-Shot Abstractive Summarization with Intermediate Fine-tuning and Data Augmentation

NAACL 2021long

Models pretrained with self-supervised objectives on large text corpora achieve state-of-the-art performance on English text summarization tasks. However, these models are typically fine-tuned on hundreds of thousands of data points, an infeasible requirement when applying summarization to new, nich…

Cited by 117SourcePDFScholar
2021

Learning Better Structured Representations Using Low-rank Adaptive Label Smoothing

ICLR 2021poster

Training with soft targets instead of hard targets has been shown to improve performance and calibration of deep neural networks. Label smoothing is a popular way of computing soft targets, where one-hot encoding of a class is smoothed with a uniform distribution. Owing to its simplicity, label smoo…

Cited by 21SourcePDFScholar
2021

RECONSIDER: Improved Re-Ranking using Span-Focused Cross-Attention for Open Domain Question Answering

NAACL 2021long

State-of-the-art Machine Reading Comprehension (MRC) models for Open-domain Question Answering (QA) are typically trained for span selection using distantly supervised positive examples and heuristically retrieved negative examples. This training scheme possibly explains empirical observations that…

2021

Syntax-augmented Multilingual BERT for Cross-lingual Transfer

ACL 2021long

In recent years, we have seen a colossal effort in pre-training multilingual text encoders using large-scale corpora in many languages to facilitate cross-lingual transfer learning. However, due to typological differences across languages, the cross-lingual transfer is challenging. Nevertheless, lan…

2021

Towards Understanding the Behaviors of Optimal Deep Active Learning Algorithms

AISTATS 2021poster

Active learning (AL) algorithms may achieve better performance with fewer data because the model guides the data selection process. While many algorithms have been proposed, there is little study on what the optimal AL algorithm looks like, which would help researchers understand where their models…