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Muhammad Khalifa

15 accepted papers

2026

Process Reward Models That Think

ICML 2026poster

Step-by-step verifiers—also known as process reward models (PRMs)—are a key ingredient for test-time scaling, but training them requires expensive step-level supervision. This work aims to build data-efficient PRMs as verbalized step-wise reward models that verify every step in the solution by gener…

Cited by 0SourcecodeScholar
2025

FACTCHECKMATE: Preemptively Detecting and Mitigating Hallucinations in LMs

EMNLP 2025

Language models (LMs) hallucinate. We inquire: Can we detect and mitigate hallucinations before they happen? This work answers this research question in the positive, by showing that the internal representations of LMs provide rich signals that can be used for this purpose. We introduce FactCheckmat

Cited by 0SourcePDFScholar
2025

MLRC-Bench: Can Language Agents Solve Machine Learning Research Challenges?

NeurIPS 2025poster

We introduce **MLRC-Bench**, a benchmark designed to quantify how effectively language agents can tackle challenging **M**achine **L**earning (ML) **R**esearch **C**ompetitions, with a focus on open research problems that demand novel methodologies. Unlike prior work, e.g., AI Scientist, which evalu…

Cited by 0SourceScholar
2024

Has It All Been Solved? Open NLP Research Questions Not Solved by Large Language Models

COLING 2024main

Recent progress in large language models (LLMs) has enabled the deployment of many generative NLP applications. At the same time, it has also led to a misleading public discourse that “it’s all been solved.” Not surprisingly, this has, in turn, made many NLP researchers – especially those at the beg…

Cited by 9SourcePDFScholar
2024

Learning to Reason via Program Generation, Emulation, and Search

NeurIPS 2024poster

Program synthesis with language models (LMs) has unlocked a large set of reasoning abilities; code-tuned LMs have proven adept at generating programs that solve a wide variety of algorithmic symbolic manipulation tasks (e.g. word concatenation). However, not all reasoning tasks are easily expressibl…

2024

LitCab: Lightweight Language Model Calibration over Short- and Long-form Responses

ICLR 2024poster

A model is considered well-calibrated when its probability estimate aligns with the actual likelihood of the output being correct. Calibrating language models (LMs) is crucial, as it plays a vital role in detecting and mitigating hallucinations of LMs as well as building more trustworthy models. How…

2024

Small Language Models Need Strong Verifiers to Self-Correct Reasoning

ACL 2024findings

Self-correction has emerged as a promising solution to boost the reasoning performance of large language models (LLMs), where LLMs refine their solutions using self-generated critiques that pinpoint the errors. This work explores whether small (≤ 13B) language models (LMs) have the ability of self-c…

2023

Contrastive Training Improves Zero-Shot Classification of Semi-structured Documents

ACL 2023findings

We investigate semi-structured document classification in a zero-shot setting. Classification of semi-structured documents is more challenging than that of standard unstructured documents, as positional, layout, and style information play a vital role in interpreting such documents. The standard cla…

2023

Few-shot Reranking for Multi-hop QA via Language Model Prompting

ACL 2023long

We study few-shot reranking for multi-hop QA (MQA) with open-domain questions. To alleviate the need for a large number of labeled question-document pairs for retriever training, we propose PromptRank, which relies on language model prompting for multi-hop path reranking. PromptRank first constructs…

Cited by 17SourcePDFScholar
2023

GRACE: Discriminator-Guided Chain-of-Thought Reasoning

EMNLP 2023long findings

In the context of multi-step reasoning, e.g., with chain-of-thought, language models (LMs) can easily assign a high likelihood to incorrect steps. As a result, decoding strategies that optimize for solution likelihood often yield incorrect solutions. To address this issue, we propose Guiding chain-o…

Cited by 0SourcecodeScholar
2023

Merging Generated and Retrieved Knowledge for Open-Domain QA

EMNLP 2023long main

Open-domain question answering (QA) systems are often built with retrieval modules. However, retrieving passages from a given source is known to suffer from insufficient knowledge coverage. Alternatively, prompting large language models (LLMs) to generate contextual passages based on their parametri…

Cited by 0SourcecodeScholar
2021

A Distributional Approach to Controlled Text Generation

ICLR 2021oral

We propose a Distributional Approach for addressing Controlled Text Generation from pre-trained Language Models (LM). This approach permits to specify, in a single formal framework, both “pointwise’” and “distributional” constraints over the target LM — to our knowledge, the first model with su…