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20,240 real negative results, null findings, and replication failures · Negative / Null Result Report. Search the index →

WASTE indexes published research — it does not host or republish full papers. Each entry is a metadata record compiled from open scholarly databases; the abstract is shown in full only where the paper is openly licensed, otherwise a short excerpt under fair use. Classifications are automated and approximate.

Negative / Null Result ReportOpen accessComputer Science

LLaMa-SciQ: An Educational Chatbot for Answering Science MCQ

Marc-Antoine Allard, Matin Ansaripour, Maria Yuffa et al. · 2024 · arXiv

Large Language Models (LLMs) often struggle with tasks requiring mathematical reasoning, particularly multiple-choice questions (MCQs). To address this issue, we developed LLaMa-SciQ, an educational chatbot designed to assist college students in solving and understanding MCQs in STEM fields. We begin by fine-tuning and aligning the models to human preferences. After comparing the performance of Mistral-7B and LLaMa-8B, we selected the latter as the base model due to its higher evaluation accuracy. To further enhance accuracy, we implement Retrieval-Augmented Generation (RAG) and apply quantiza

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Negative / Null Result ReportOpen accessComputer Science

Maximizing Prefix-Confidence at Test-Time Efficiently Improves Mathematical Reasoning

Matthias Otth, Jonas Hübotter, Ido Hakimi et al. · 2025 · arXiv

Recent work has shown that language models can self-improve by maximizing their own confidence in their predictions, without relying on external verifiers or reward signals. In this work, we study the test-time scaling of language models for mathematical reasoning tasks, where the model's own confidence is used to select the most promising attempts. Surprisingly, we find that we can achieve significant performance gains by continuing only the most promising attempt, selected by the model's prefix-confidence. We systematically evaluate prefix-confidence scaling on five mathematical reasoning da

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Negative / Null Result ReportOpen accessComputer Science

Long-Tail Crisis in Nearest Neighbor Language Models

Yuto Nishida, Makoto Morishita, Hiroyuki Deguchi et al. · 2025 · arXiv

The $k$-nearest-neighbor language model ($k$NN-LM), one of the retrieval-augmented language models, improves the perplexity for given text by directly accessing a large datastore built from any text data during inference. A widely held hypothesis for the success of $k$NN-LM is that its explicit memory, i.e., the datastore, enhances predictions for long-tail phenomena. However, prior works have primarily shown its ability to retrieve long-tail contexts, leaving the model's performance remain underexplored in estimating the probabilities of long-tail target tokens during inference. In this paper

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Negative / Null Result ReportOpen accessComputer Science

Perfect quantum excitation energy transport via single edge perturbation in a complete network

Hassan Bassereh, Vahid Salari, Farhad Shahbazi et al. · 2015 · arXiv

We consider quantum excitation energy transport (EET) in a network of two-state nodes in the Markovian approximation by employing the Lindblad formulation. We find that EET from an initial site, where the excitation is inserted to the sink, is generally inefficient due to the inhibition of transport by localization of the excitation wave packet in a symmetric, fully-connected network. We demonstrate that the EET efficiency can be significantly increased up to %100 by perturbing hopping transport between the initial node and the one connected directly to the sink, while the rate of energy trans

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Negative / Null Result ReportOpen accessComputer Science

DVB-S2 Spectrum Efficiency Improvement with Hierarchical Modulation

Hugo Meric, Jose Miguel Piquer · 2013 · arXiv

We study the design of a DVB-S2 system in order to maximise spectrum efficiency. This task is usually challenging due to channel variability. Modern satellite communications systems such as DVB-SH and DVB-S2 rely mainly on a time sharing strategy to optimise the spectrum efficiency. Recently, we showed that combining time sharing with hierarchical modulation can provide significant gains (in terms of spectrum efficiency) compared to the best time sharing strategy. However, our previous design does not improve the DVB-S2 performance when all the receivers experience low or large signal-to-noise

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Negative / Null Result ReportOpen accessComputer Science

Is Bottom-Up Attention Useful for Scene Recognition?

Samuel F. Dodge, Lina J. Karam · 2013 · arXiv

The human visual system employs a selective attention mechanism to understand the visual world in an eficient manner. In this paper, we show how computational models of this mechanism can be exploited for the computer vision application of scene recognition. First, we consider saliency weighting and saliency pruning, and provide a comparison of the performance of different attention models in these approaches in terms of classification accuracy. Pruning can achieve a high degree of computational savings without significantly sacrificing classification accuracy. In saliency weighting, however,

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Negative / Null Result ReportOpen accessComputer Science

Towards Deep Robot Learning with Optimizer applicable to Non-stationary Problems

Taisuke Kobayashi · 2020 · arXiv

This paper proposes a new optimizer for deep learning, named d-AmsGrad. In the real-world data, noise and outliers cannot be excluded from dataset to be used for learning robot skills. This problem is especially striking for robots that learn by collecting data in real time, which cannot be sorted manually. Several noise-robust optimizers have therefore been developed to resolve this problem, and one of them, named AmsGrad, which is a variant of Adam optimizer, has a proof of its convergence. However, in practice, it does not improve learning performance in robotics scenarios. This reason is h

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Negative / Null Result ReportOpen accessComputer Science

Background Knowledge Grounding for Readable, Relevant, and Factual Biomedical Lay Summaries

Domenic Rosati · 2023 · arXiv

Communication of scientific findings to the public is important for keeping non-experts informed of developments such as life-saving medical treatments. However, generating readable lay summaries from scientific documents is challenging, and currently, these summaries suffer from critical factual errors. One popular intervention for improving factuality is using additional external knowledge to provide factual grounding. However, it is unclear how these grounding sources should be retrieved, selected, or integrated, and how supplementary grounding documents might affect the readability or rele

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Negative / Null Result ReportOpen accessComputer Science

Non-unitary neutrino mixing in the NO$ν$A near detector data

Ushak Rahaman, Soebur Razzaque · 2021 · arXiv

The $ν_μ\to ν_e$ oscillation probability over short baseline ($\lesssim 1$~km) would be negligible in case the mixing matrix for three active neutrinos is unitary. However, in case of non-unitary mixing of three neutrinos, this probability would be non-negligible due to the so-called "zero distance" effect. Hence, the near detector of the accelerator experiments such as NO$ν$A can provide strong constraints on the parameters of the non-unitary mixing with very large statistics. By analyzing the NO$ν$A near detector data we find that the non-unitary mixing does not improve fits to the $ν_e$ or

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Negative / Null Result ReportOpen accessComputer Science

Joint-sparse recovery from multiple measurements

Ewout van den Berg, Michael P. Friedlander · 2009 · arXiv

The joint-sparse recovery problem aims to recover, from sets of compressed measurements, unknown sparse matrices with nonzero entries restricted to a subset of rows. This is an extension of the single-measurement-vector (SMV) problem widely studied in compressed sensing. We analyze the recovery properties for two types of recovery algorithms. First, we show that recovery using sum-of-norm minimization cannot exceed the uniform recovery rate of sequential SMV using $\ell_1$ minimization, and that there are problems that can be solved with one approach but not with the other. Second, we analyze

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Negative / Null Result ReportOpen accessAgricultural and Biological Sciences

Optimizing fMRI Data Acquisition for Decoding Natural Speech with Limited Participants

Louis Jalouzot, Alexis Thual, Yair Lakretz et al. · 2025 · arXiv

We investigate optimal strategies for decoding perceived natural speech from fMRI data acquired from a limited number of participants. Leveraging Lebel et al. (2023)'s dataset of 8 participants, we first demonstrate the effectiveness of training deep neural networks to predict LLM-derived text representations from fMRI activity. Then, in this data regime, we observe that multi-subject training does not improve decoding accuracy compared to single-subject approach. Furthermore, training on similar or different stimuli across subjects has a negligible effect on decoding accuracy. Finally, we fin

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Negative / Null Result ReportOpen accessComputer Science

The Unlearnability Phenomenon in RLVR for Language Models

Yulin Chen, He He, Chen Zhao · 2026 · arXiv

Reinforcement Learning with Verifiable Reward (RLVR) has proven effective in improving Large Language Model's (LLM) reasoning ability. However, the learning dynamics of RLVR remain underexplored. In this paper, we reveal a counterintuitive phenomenon: among hard examples that the model initially struggles with, a substantial subset remains unlearnable even when correct rollouts are present. To understand the phenomenon, we first demonstrate that existing optimization and sampling techniques fail to resolve unlearnability. With cross-example gradient analysis, we show that unlearnable examples

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Negative / Null Result ReportOpen accessComputer Science

Debate or Vote: Which Yields Better Decisions in Multi-Agent Large Language Models?

Hyeong Kyu Choi, Xiaojin Zhu, Sharon Li · 2025 · arXiv

Multi-Agent Debate~(MAD) has emerged as a promising paradigm for improving the performance of large language models through collaborative reasoning. Despite recent advances, the key factors driving MAD's effectiveness remain unclear. In this work, we disentangle MAD into two key components--Majority Voting and inter-agent Debate--and assess their respective contributions. Through extensive experiments across seven NLP benchmarks, we find that Majority Voting alone accounts for most of the performance gains typically attributed to MAD. To explain this, we propose a theoretical framework that mo

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Negative / Null Result ReportOpen accessComputer Science

Compressing BERT: Studying the Effects of Weight Pruning on Transfer Learning

Mitchell A. Gordon, Kevin Duh, Nicholas Andrews · 2020 · arXiv

Pre-trained universal feature extractors, such as BERT for natural language processing and VGG for computer vision, have become effective methods for improving deep learning models without requiring more labeled data. While effective, feature extractors like BERT may be prohibitively large for some deployment scenarios. We explore weight pruning for BERT and ask: how does compression during pre-training affect transfer learning? We find that pruning affects transfer learning in three broad regimes. Low levels of pruning (30-40%) do not affect pre-training loss or transfer to downstream tasks a

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Negative / Null Result ReportOpen accessComputer Science

Linguistic Features for Readability Assessment

Tovly Deutsch, Masoud Jasbi, Stuart Shieber · 2020 · arXiv

Readability assessment aims to automatically classify text by the level appropriate for learning readers. Traditional approaches to this task utilize a variety of linguistically motivated features paired with simple machine learning models. More recent methods have improved performance by discarding these features and utilizing deep learning models. However, it is unknown whether augmenting deep learning models with linguistically motivated features would improve performance further. This paper combines these two approaches with the goal of improving overall model performance and addressing th

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Negative / Null Result ReportOpen accessComputer Science

Upper Energy Limit of Heavy Baryon Chiral Perturbation Theory in Neutral Pion Photoproduction

C. Fernandez-Ramirez, A. M. Bernstein · 2012 · arXiv

With the availability of the new neutral pion photoproduction from the proton data from the A2 and CB-TAPS Collaborations at Mainz it is mandatory to revisit Heavy Baryon Chiral Perturbation Theory (HBChPT) and address the extraction of the partial waves as well as other issues such as the value of the low-energy constants, the energy range where the calculation provides a good agreement with the data and the impact of unitarity. We find that, within the current experimental status, HBChPT with the fitted LECs gives a good agreement with the existing neutral pion photoproduction data up to $\s

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Negative / Null Result ReportOpen accessComputer Science

Source Coding When the Side Information May Be Delayed

Osvaldo Simeone, Haim H. Permuter · 2011 · arXiv

For memoryless sources, delayed side information at the decoder does not improve the rate-distortion function. However, this is not the case for more general sources with memory, as demonstrated by a number of works focusing on the special case of (delayed) feedforward. In this paper, a setting is studied in which the encoder is potentially uncertain about the delay with which measurements of the side information are acquired at the decoder. Assuming a hidden Markov model for the sources, at first, a single-letter characterization is given for the set-up where the side information delay is arb

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Negative / Null Result ReportOpen accessComputer Science

From Co-Design to Metacognitive Laziness: Evaluating Generative AI in Vocational Education

Amir Yunus, Peng Rend Gay, Oon Teng Lee · 2025 · arXiv

This study examines the development and deployment of a Generative AI proof-of-concept (POC) designed to support lecturers in a vocational education setting in Singapore. Employing a user-centred, mixed-methods design process, we co-developed an AI chatbot with lecturers to address recurring instructional challenges during exam preparation, specifically managing repetitive questions and scaling feedback delivery. The POC achieved its primary operational goals: lecturers reported streamlined workflows, reduced cognitive load, and observed improved student confidence in navigating course content

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Negative / Null Result ReportOpen accessMathematics

Cowen's class and Thomson's class

Kunyu Guo, Hansong Huang · 2013 · arXiv

In studying commutants of analytic Toeplitz operators, Thomson proved a remarkable theorem which states that under a mild condition, the commutant of an analytic Toeplitz operator is equal to that of Toeplitz operator defined by a finite Blaschke product. Cowen gave an significant improvement of Thosom's result. In this paper, we will present examples in Cowen's class which does not lie in Thomson's class.

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Negative / Null Result Report

Did I really agree to that?: making sense of policies you didn’t read with models that actually did

Shikha Soneji, Mitchell Hoesing, Sujay Koujalgi et al. · 2026 · Information Research an international electronic journal

Introduction. While Privacy Policies and Terms of Service (ToS) are intended to inform users; they often overwhelm, mislead, and confuse in practice. This work investigates automated techniques for analyzing such legal documents, with the…

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Negative / Null Result ReportOpen accessComputer Science

Refined Continuous Control of DDPG Actors via Parametrised Activation

Mohammed Hossny, Julie Iskander, Mohammed Attia et al. · 2020 · arXiv

In this paper, we propose enhancing actor-critic reinforcement learning agents by parameterising the final actor layer which produces the actions in order to accommodate the behaviour discrepancy of different actuators, under different load conditions during interaction with the environment. We propose branching the action producing layer in the actor to learn the tuning parameter controlling the activation layer (e.g. Tanh and Sigmoid). The learned parameters are then used to create tailored activation functions for each actuator. We ran experiments on three OpenAI Gym environments, i.e. Pend

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Negative / Null Result ReportOpen accessComputer Science

MaScQA: A Question Answering Dataset for Investigating Materials Science Knowledge of Large Language Models

Mohd Zaki, Jayadeva, Mausam et al. · 2023 · arXiv

Information extraction and textual comprehension from materials literature are vital for developing an exhaustive knowledge base that enables accelerated materials discovery. Language models have demonstrated their capability to answer domain-specific questions and retrieve information from knowledge bases. However, there are no benchmark datasets in the materials domain that can evaluate the understanding of the key concepts by these language models. In this work, we curate a dataset of 650 challenging questions from the materials domain that require the knowledge and skills of a materials st

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Negative / Null Result Report

No significant effect of acupuncture on assisted pregnancy

L Rose · 2011 · Focus on Alternative and Complementary Therapies

Andersen D, Løssl K, Andersen AN, Fürbringer J, Bach H, Simonsen J, Larsen EC. Acupuncture on the day of embryo transfer: a randomized controlled trial of 635 patients. Reprod Biomed Online 2010; 21: 366–372.

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