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Yftah Ziser

16 accepted papers

2026

Beyond Next Token Probabilities: Learnable, Fast Detection of Hallucinations and Data Contamination on LLM Output Distributions

AAAI 2026technical

The automated detection of hallucinations and training data contamination is pivotal to the safe deployment of Large Language Models (LLMs). These tasks are particularly challenging in settings where no access to model internals is available. Current approaches in this setup typically leverage only

Cited by 0SourcePDFScholar
2026

Neural Message-Passing on Attention Graphs for Hallucination Detection

ICLR 2026poster

Large Language Models (LLMs) often generate incorrect or unsupported content, known as hallucinations. Existing detection methods rely on heuristics or simple models over isolated computational traces such as activations, or attention maps. We unify these signals by representing them as attributed g…

Cited by 0SourcecodeScholar
2025

A Simple Yet Effective Method for Non-Refusing Context Relevant Fine-grained Safety Steering in LLMs

EMNLP 2025

Fine-tuning large language models (LLMs) to meet evolving safety policies is costly and impractical. Mechanistic interpretability enables inference-time control through latent activation steering, but its potential for precise, customizable safety adjustments remains underexplored. We propose SafeSt

2025

Beyond Token Probes: Hallucination Detection via Activation Tensors with ACT-ViT

NeurIPS 2025poster

Detecting hallucinations in Large Language Model-generated text is crucial for their safe deployment. While probing classifiers show promise, they operate on isolated layer–token pairs and are LLM-specific, limiting their effectiveness and hindering cross-LLM applications. In this paper, we introduc…

Cited by 0SourceScholar
2025

Iterative Multilingual Spectral Attribute Erasure

EMNLP 2025

Multilingual representations embed words with similar meanings to share a common semantic space across languages, creating opportunities to transfer debiasing effects between languages. However, existing methods for debiassing are unable to exploit this opportunity because they operate on individual

Cited by 0SourcePDFScholar
2025

Knowing Before Saying: LLM Representations Encode Information About Chain-of-Thought Success Before Completion

ACL 2025finding

We investigate whether the success of a zero-shot Chain-of-Thought (CoT) process can be predicted before completion. Our classifier, based on LLM representations, performs well even before a single token is generated, suggesting that crucial information about the reasoning process is already present…

2024

Are Large Language Model Temporally Grounded?

NAACL 2024long

Are Large Language Models (LLMs) temporally grounded? Since LLMs cannot perceive and interact with the environment, it is impossible to answer this question directly. Instead, we provide LLMs with textual narratives and probe them with respect to their common-sense knowledge of the structure and dur…

Cited by 19SourcePDFScholar
2024

Layer by Layer: Uncovering Where Multi-Task Learning Happens in Instruction-Tuned Large Language Models

EMNLP 2024main

Fine-tuning pre-trained large language models (LLMs) on a diverse array of tasks has become a common approach for building models that can solve various natural language processing (NLP) tasks. However, where and to what extent these models retain task-specific knowledge remains largely unexplored.…

2024

Spectral Editing of Activations for Large Language Model Alignment

NeurIPS 2024poster

Large language models (LLMs) often exhibit undesirable behaviours, such as generating untruthful or biased content. Editing their internal representations has been shown to be effective in mitigating such behaviours on top of the existing alignment methods. We propose a novel inference-time editing…

2023

A Joint Matrix Factorization Analysis of Multilingual Representations

EMNLP 2023long findings

We present an analysis tool based on joint matrix factorization for comparing latent representations of multilingual and monolingual models. An alternative to probing, this tool allows us to analyze multiple sets of representations in a joint manner. Using this tool, we study to what extent and how…

Cited by 0SourcecodeScholar
2023

Detecting and Mitigating Hallucinations in Multilingual Summarisation

EMNLP 2023long main

Hallucinations pose a significant challenge to the reliability of neural models for abstractive summarisation. While automatically generated summaries may be fluent, they often lack faithfulness to the original document. This issue becomes even more pronounced in low-resource languages, where summar…

Cited by 0SourcecodeScholar
2022

Factorizing Content and Budget Decisions in Abstractive Summarization of Long Documents

EMNLP 2022main

We argue that disentangling content selection from the budget used to cover salient content improves the performance and applicability of abstractive summarizers. Our method, FactorSum, does this disentanglement by factorizing summarization into two steps through an energy function: (1) generation o…

2021

Answering Product-Questions by Utilizing Questions from Other Contextually Similar Products

NAACL 2021long

Predicting the answer to a product-related question is an emerging field of research that recently attracted a lot of attention. Answering subjective and opinion-based questions is most challenging due to the dependency on customer generated content. Previous works mostly focused on review-aware ans…

2021

DILBERT: Customized Pre-Training for Domain Adaptation with Category Shift, with an Application to Aspect Extraction

EMNLP 2021main

The rise of pre-trained language models has yielded substantial progress in the vast majority of Natural Language Processing (NLP) tasks. However, a generic approach towards the pre-training procedure can naturally be sub-optimal in some cases. Particularly, fine-tuning a pre-trained language model…

2021

WikiSum: Coherent Summarization Dataset for Efficient Human-Evaluation

ACL 2021short

Recent works made significant advances on summarization tasks, facilitated by summarization datasets. Several existing datasets have the form of coherent-paragraph summaries. However, these datasets were curated from academic documents that were written for experts, thus making the essential step of…