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Omri Abend

27 accepted papers

2026

Control Illusion: The Failure of Instruction Hierarchies in Large Language Models

AAAI 2026technical

Large language models (LLMs) are increasingly deployed with hierarchical instruction schemes, where certain instructions (e.g., system-level directives) are expected to take precedence over others (e.g., user messages). Yet, we lack a systematic understanding of how effectively these hierarchical co

Cited by 0SourcePDFScholar
2026

Position: Express Your Doubts — Probabilistic World Modeling Should not be Based on Token *logprobs*

ICML 2026poster

Language modeling has shifted in recent years from a distribution over strings to prediction models with textual inputs and outputs for general-purpose tasks. This position paper highlights the often overlooked implications of this shift for the use of large language models (LLMs) as probability est…

Cited by 0SourceScholar
2025

Computational Analysis of Character Development in Holocaust Testimonies

EMNLP 2025

This work presents a computational approach to analyze character development along the narrative timeline. The analysis characterizes changes in the protagonist’s views and behavior and the interplay between them. We consider transcripts of Holocaust survivor testimonies as a test case, each telling

2025

Jamba: Hybrid Transformer-Mamba Language Models

ICLR 2025poster

We present Jamba, a novel hybrid Transformer-Mamba mixture-of-experts (MoE) architecture. Jamba interleaves blocks of Transformer and Mamba layers, enjoying the benefits of both model families. MoE is added in some of these layers to increase model capacity while keeping active parameter usage manag…

Cited by 3SourcePDFScholar
2025

Mind Your Theory: Theory of Mind Goes Deeper Than Reasoning

ACL 2025finding

Theory of Mind (ToM) capabilities in LLMs have recently become a central object of investigation, sparking debates and discussions. In this position paper, we explore many lines of work in different communities in AI and cognitive science. Inspired by cognitive work, we view ToM tasks as a two-step…

2025

T5Score: A Methodology for Automatically Assessing the Quality of LLM Generated Multi-Document Topic Sets

ACL 2025finding

Using LLMs for Multi-Document Topic Extraction has recently gained popularity due to their apparent high-quality outputs, expressiveness, and ease of use. However, most existing evaluation practices are not designed for LLM-generated topics and result in low inter-annotator agreement scores, hinderi…

2024

CONTESTS: a Framework for Consistency Testing of Span Probabilities in Language Models

EMNLP 2024main

Although language model scores are often treated as probabilities, their reliability as probability estimators has mainly been studied through calibration, overlooking other aspects. In particular, it is unclear whether language models produce the same value for different ways of assigning joint pro…

Cited by 0SourcePDFScholar
2024

Locally Measuring Cross-lingual Lexical Alignment: A Domain and Word Level Perspective

EMNLP 2024finding

NLP research on aligning lexical representation spaces to one another has so far focused on aligning language spaces in their entirety. However, cognitive science has long focused on a local perspective, investigating whether translation equivalents truly share the same meaning or the extent that cu…

2023

DisentQA: Disentangling Parametric and Contextual Knowledge with Counterfactual Question Answering

ACL 2023long

Question answering models commonly have access to two sources of “knowledge” during inference time: (1) parametric knowledge - the factual knowledge encoded in the model weights, and (2) contextual knowledge - external knowledge (e.g., a Wikipedia passage) given to the model to generate a grounded a…

2023

Event-Location Tracking in Narratives: A Case Study on Holocaust Testimonies

EMNLP 2023long main

This work focuses on the spatial dimension of narrative understanding and presents the task of event-location tracking in narrative texts. The task intends to extract the sequence of locations where the narrative is set through its progression. We present several architectures for the task that seek…

Cited by 0SourceScholar
2023

Human Learning by Model Feedback: The Dynamics of Iterative Prompting with Midjourney

EMNLP 2023long main

Generating images with a Text-to-Image model often requires multiple trials, where human users iteratively update their prompt based on feedback, namely the output image. Taking inspiration from cognitive work on reference games and dialogue alignment, this paper analyzes the dynamics of the user pr…

Cited by 0SourcecodeScholar
2023

Improving Cross-lingual Transfer through Subtree-aware Word Reordering

EMNLP 2023long findings

Despite the impressive growth of the abilities of multilingual language models, such as XLM-R and mT5, it has been shown that they still face difficulties when tackling typologically-distant languages, particularly in the low-resource setting. One obstacle for effective cross-lingual transfer is var…

Cited by 0SourcecodeScholar
2023

Parallel Context Windows for Large Language Models

ACL 2023long

When applied to processing long text, Large Language Models (LLMs) are limited by their context window. Existing efforts to address this limitation involve training specialized architectures, and cannot be easily applied to off- the-shelf LLMs. We present Parallel Context Windows (PCW), a method tha…

2022

A Computational Acquisition Model for Multimodal Word Categorization

NAACL 2022long

Recent advances in self-supervised modeling of text and images open new opportunities for computational models of child language acquisition, which is believed to rely heavily on cross-modal signals. However, prior studies has been limited by their reliance on vision models trained on large image da…

2022

PreQuEL: Quality Estimation of Machine Translation Outputs in Advance

EMNLP 2022main

We present the task of PreQuEL, Pre-(Quality-Estimation) Learning. A PreQuEL system predicts how well a given sentence will be translated, without recourse to the actual translation, thus eschewing unnecessary resource allocation when translation quality is bound to be low. PreQuEL can be defined re…

2022

Reinforcement Learning with Large Action Spaces for Neural Machine Translation

COLING 2022main

Applying Reinforcement learning (RL) following maximum likelihood estimation (MLE) pre-training is a versatile method for enhancing neural machine translation (NMT) performance. However, recent work has argued that the gains produced by RL for NMT are mostly due to promoting tokens that have already…

2022

The Grammar-Learning Trajectories of Neural Language Models

ACL 2022long

The learning trajectories of linguistic phenomena in humans provide insight into linguistic representation, beyond what can be gleaned from inspecting the behavior of an adult speaker. To apply a similar approach to analyze neural language models (NLM), it is first necessary to establish that differ…

2022

Topical Segmentation of Spoken Narratives: A Test Case on Holocaust Survivor Testimonies

EMNLP 2022main

The task of topical segmentation is well studied, but previous work has mostly addressed it in the context of structured, well-defined segments, such as segmentation into paragraphs, chapters, or segmenting text that originated from multiple sources. We tackle the task of segmenting running (spoken)…

2021

On the Relation between Syntactic Divergence and Zero-Shot Performance

EMNLP 2021main

We explore the link between the extent to which syntactic relations are preserved in translation and the ease of correctly constructing a parse tree in a zero-shot setting. While previous work suggests such a relation, it tends to focus on the macro level and not on the level of individual edges—a g…

2021

PMI-Masking: Principled masking of correlated spans

ICLR 2021spotlight

Masking tokens uniformly at random constitutes a common flaw in the pretraining of Masked Language Models (MLMs) such as BERT. We show that such uniform masking allows an MLM to minimize its training objective by latching onto shallow local signals, leading to pretraining inefficiency and suboptimal…

Cited by 81SourcePDFScholar
2021

Putting Words in BERT’s Mouth: Navigating Contextualized Vector Spaces with Pseudowords

EMNLP 2021main

We present a method for exploring regions around individual points in a contextualized vector space (particularly, BERT space), as a way to investigate how these regions correspond to word senses. By inducing a contextualized “pseudoword” vector as a stand-in for a static embedding in the input laye…

2021

Q2: Evaluating Factual Consistency in Knowledge-Grounded Dialogues via Question Generation and Question Answering

EMNLP 2021main

Neural knowledge-grounded generative models for dialogue often produce content that is factually inconsistent with the knowledge they rely on, making them unreliable and limiting their applicability. Inspired by recent work on evaluating factual consistency in abstractive summarization, we propose a…

2020

Comparison by Conversion: Reverse-Engineering UCCA from Syntax and Lexical Semantics

COLING 2020main

Building robust natural language understanding systems will require a clear characterization of whether and how various linguistic meaning representations complement each other. To perform a systematic comparative analysis, we evaluate the mapping between meaning representations from different frame…

2020

On the Weaknesses of Reinforcement Learning for Neural Machine Translation

ICLR 2020poster

Reinforcement learning (RL) is frequently used to increase performance in text generation tasks, including machine translation (MT), notably through the use of Minimum Risk Training (MRT) and Generative Adversarial Networks (GAN). However, little is known about what and how these methods learn in…

Cited by 98SourceScholar