If We May De-Presuppose: Robustly Verifying Claims through Presupposition-Free Question Decomposition (2025)

Abstract: Prior work has shown that presupposition in generated questions can introduce unverified assumptions, leading to inconsistencies in claim verification. Additionally, prompt sensitivity remains a significant challenge for large language models (LLMs), resulting in performance variance as high as **3–6%**. While recent advancements have reduced this gap, our study demonstrates that prompt sensitivity remains a persistent issue. To address this, we propose a structured and robust claim verification framework that reasons through presupposition-free, decomposed questions. Extensive experiments across multiple prompts, datasets, and LLMs reveal that even state-of-the-art models remain susceptible to prompt variance and presupposition. Our method consistently mitigates these issues, achieving up to a **2–5%** improvement.

## introduction while current large language models (llms) @xcite @xcite demonstrate strong performance in claim verification @xcite when provided with ground truth evidence, they can improperly presuppose parts of the claim, which can then lead to incorrect conclusions or explanations. consider, for example, the claim illustrated in fig. 1 : "a bollywood movie won the oscar in 1928": an llm might simply verify whether "any bollywood movie won the 1928 oscar," thereby accepting the existence of the 1928 oscar without verifying it first. 2 in contrast, a more skeptical verifier would first ask, "was there an oscar in 1928?" -and only if that is true, proceed to verify the rest of the claim. this multi-layered reasoning highlights the need for decomposition-based verifi-1 https://github.com/dipta007/de-presuppose 2 the oscars were first awarded in 1929. ## method given a claim ("bollywood movie has won the oscar in 1928"), our approach proceeds in three steps: first, we automatically decompose the claim into simpler questions ( §2.1) -"which bollywood movie has won the oscar in 1928?". we recognize that the generated questions may presuppose certain facts, such as "there was an oscar award in 1928." to account for this, we next reformulate and expand these questions to remove presuppositions, resulting in presupposition-free questions ( §2.2) -"(a) was there an oscar in 1928?, (b) if there was, has any bollywood movie won that? (c) if yes, which one was that?" finally, we use a reasoner to verify the claim ( §2.3) with the help of these questions. our results show that this structuring improves claim verification performance. @xcite demonstrated that using evidence during question generation yields significantly better results. motivated by this, we incorporate both claim and evidence in our question generation process. inductively, we prompt an llm to decompose a claim into separate, independent questions 3 . we adopted the prompt from @xcite to better align with our question decomposition module instead of their subclaim decomposition. specifically, their few-shot prompt includes examples of claim-to-subclaim decomposition, which we adapted by converting the assertive statements into questions. ## experiments evaluation metric: we used balanced accuracy (bacc) as the evaluation metric @xcite , due to the imbalance between all the labels. to evaluate our question module, we have proposed a question coverage metric to assess the accuracy of generated questions ( §3.2). ## related works many works have explored claim verification @xcite @xcite @xcite , but the decomposition of claims into our method 1. when did rowney make his nhl debut? … 1. did rowney have an nhl debut game? 2. if rowney was in the nhl, when did he make his debut? … <@xmath0, looking at the document: … now, the questions and answers provided. question 1 and 2 answer that rowney had his debut in that specific game on jan 31. question 1 asks if he had his debut in pittsburgh's 4-2 win over the predators on that date. it confirms the same details. … answer of quesion 3 confirms rowney's debut with pittsburgh on that date against the predators. all the relevant answers align with the document's information. the document clearly states he suited up in the game on jan 31, which is considered his debut. therefore, all parts of the claim are supported. ## conclusion we introduce a novel question decomposition approach for generating presupposition-free, atomic questions that systematically interrogate each part of a claim. this study is inspired by how humans think by decomposing and verifying each part of a complex claim. using our approach, we have shown that we can mitigate the prompt sensitivity by constraining it to thinking structurally than free form. we hope this line of research encourages further exploration into decomposition-based reasoning as a foundation for building more trustworthy and transparent claim verification systems.