Negative / Null Result ReportOpen accessComputer Science
Xu Ma, Jiajie Zhang, Fujing Xie et al. · 2025 · arXiv
Global localization is essential for autonomous robotics, especially in indoor environments where the GPS signal is denied. We propose a novel WiFi-based localization framework that leverages ubiquitous wireless infrastructure and the OpenStreetMap Area Graph (osmAG) for large-scale indoor environments. Our approach integrates signal propagation modeling with osmAG's geometric and topological priors. In the offline phase, an iterative optimization algorithm localizes WiFi Access Points (APs) by modeling wall attenuation, achieving a mean localization error of 3.79 m (35.3\% improvement over tr
Negative / Null Result ReportOpen accessMathematics
John Rozmarynowycz, Seungki Kim · 2023 · arXiv
We report the finding of the new upper bound on the lowest positive integer $x$ for which the Mertens conjecture \begin{equation*} \left| \sum_{1 \leq n \leq x} μ(n) \right| < \sqrt{x} \end{equation*} fails to hold: $x < \exp(1.017 \times 10^{29})$, an improvement over previously known $\exp(1.59 \times 10^{40})$ due to Kotnik and te Riele [7].
Negative / Null Result ReportOpen accessMathematics
D. R. Heath-Brown · 2026 · arXiv
We show that there are $O(B^{3/5-3/1555+\ep})$ triples $(x,y,z)$ of square-full integesr up to $B$ satisfying the equation $x+y=z$ for any fixed $\ep>0$. This is the first improvement over the `easy' exponent $3/5$, given by Browning and Van Valckenborgh. One new tool is a strong uniform bound for the counting function for equations $aX^3+bY^3=cZ^3$.
Negative / Null Result Report
Timothy Daniel Allerton, Stefany D. Primeaux · 2013 · The FASEB Journal
The propensity for some individuals to develop obesity has been linked to intake of a high fat diet (HFD) and physical inactivity. However, some individuals resist obesity through improved energy sensing and other compensatory measures to…
View details →DOI: 10.1096/fasebj.27.1_supplement.1153.5 Negative / Null Result Report
Rosario Milelli · 2026 · Journal of Artificial Intelligence, Virtual Reality, and Human-Centered Computing
ChatGPT, developed by OpenAI, has become a central tool in my professional workflow, supporting scholarly research, editorial writing, and creative projects. Drawing on extensive practical use, this perspective highlights both its…
View details →DOI: 10.66311/3069-2318.02.01.02 Negative / Null Result Report
Mohd Faris Dziauddin · 2023 · PLANNING MALAYSIA
It is generally believed that public transport investment such as urban rail transit systems can improve accessibility, particularly in larger and denser metropolitan areas. The improved accessibility provided by urban rail transit systems…
View details →DOI: 10.21837/pm.v21i25.1243 Negative / Null Result Report
Larry Chen, Emily Berzolla, Griffith Gosnell et al. · 2025 · Journal of Hip Preservation Surgery
Abstract Background While hip arthroscopy (HA) has improved outcomes in femoroacetabular impingement syndrome (FAIS), advanced age has been considered a negative predictor of outcomes. The purpose of this study was to evaluate long-term…
View details →DOI: 10.1093/jhps/hnaf069.053 Failed Experiment Report
· 2024 · Multimedia Manual of Cardio-Thoracic Surgery
The Ross procedure provides young patients with unrepairable aortic valve disease with a living pulmonary autograft that confers significant survival benefit and improved quality of life. However, the procedure is complicated, and surgeons…
View details →DOI: 10.1510/mmcts.2024.095 Negative / Null Result ReportOpen accessPhysics
Ulrich H. E. Hansmann · 1997 · arXiv
We discuss the use of Tsallis generalized mechanics in simulated annealing algorithms. For a small peptide it is shown that older implementations are not more effective than regular simulated annealing in finding ground state configurations. We propose a new implementation which leads to an improvement over regular simulated annealing.
Failed Experiment Report
Liudmila Zakharova, Hikmet Nural, James R Nimlos et al. · 2013 · Circulation Research
A pilot clinical study using autologous c-Kit+ cells showed improvement in cardiac functions in congestive heart failure (CHF), however, it is unclear if c-Kit+ cells isolated from CHF hearts are equally as potent as cells from controls.…
View details →DOI: 10.1161/res.113.suppl_1.a131 Negative / Null Result ReportOpen accessComputer Science
Amy Zhang, Shagun Sodhani, Khimya Khetarpal et al. · 2020 · arXiv
Many control tasks exhibit similar dynamics that can be modeled as having common latent structure. Hidden-Parameter Markov Decision Processes (HiP-MDPs) explicitly model this structure to improve sample efficiency in multi-task settings. However, this setting makes strong assumptions on the observability of the state that limit its application in real-world scenarios with rich observation spaces. In this work, we leverage ideas of common structure from the HiP-MDP setting, and extend it to enable robust state abstractions inspired by Block MDPs. We derive instantiations of this new framework f
Negative / Null Result ReportOpen accessComputer Science
Adam Karczmarz · 2021 · arXiv
We consider the directed minimum weight cycle problem in the fully dynamic setting. To the best of our knowledge, so far no fully dynamic algorithms have been designed specifically for the minimum weight cycle problem in general digraphs. One can achieve $\tilde{O}(n^2)$ amortized update time by simply invoking the fully dynamic APSP algorithm of Demetrescu and Italiano [J. ACM'04]. This bound, however, yields no improvement over the trivial recompute-from-scratch algorithm for sparse graphs. Our first contribution is a very simple deterministic $(1+ε)$-approximate algorithm supporting vertex
Negative / Null Result ReportOpen accessComputer Science
Raghav Gupta, Akanksha Jain, Abraham Gonzalez et al. · 2026 · arXiv
Agile hardware design flows are a critically needed force multiplier to meet the exploding demand for compute. Recently, agentic generative AI systems have demonstrated significant advances in algorithm design, improving code efficiency, and enabling discovery across scientific domains. Bridging these worlds, we present ArchAgent, an automated computer architecture discovery system built on AlphaEvolve. We show ArchAgent's ability to automatically design/implement state-of-the-art (SoTA) cache replacement policies (architecting new mechanisms/logic, not only changing parameters), broadly withi
Negative / Null Result ReportOpen accessComputer Science
Esther Ezra, Micha Sharir · 2021 · arXiv
We consider several problems that involve lines in three dimensions, and present improved algorithms for solving them. The problems include (i) ray shooting amid triangles in $R^3$, (ii) reporting intersections between query lines (segments, or rays) and input triangles, as well as approximately counting the number of such intersections, (iii) computing the intersection of two nonconvex polyhedra, (iv) detecting, counting, or reporting intersections in a set of lines in $R^3$, and (v) output-sensitive construction of an arrangement of triangles in three dimensions. Our approach is based on the
Negative / Null Result ReportOpen accessPhysics
Tim Gould · 2012 · arXiv
The "ACFD-RPA" correlation energy functional has been widely applied to a variety of systems to successfully predict energy differences, and less successfully predict absolute correlation energies. Here we present a parameter-free exchange-correlation kernel that systematically improves absolute correlation energies, while maintaining most of the good numerical properties that make the ACFD-RPA numerically tractable. The "RXH" kernel is constructed to approximate the true exchange kernel via a carefully weighted, easily computable radial averaging. Correlation energy errors of atoms with two t
Negative / Null Result ReportOpen accessComputer Science
Donny Cheung, Dmitri Maslov, Jimson Mathew et al. · 2007 · arXiv
We consider a quantum polynomial-time algorithm which solves the discrete logarithm problem for points on elliptic curves over $GF(2^m)$. We improve over earlier algorithms by constructing an efficient circuit for multiplying elements of binary finite fields and by representing elliptic curve points using a technique based on projective coordinates. The depth of our proposed implementation, executable in the Linear Nearest Neighbor (LNN) architecture, is $O(m^2)$, which is an improvement over the previous bound of $O(m^3)$ derived assuming no architectural restrictions.
Negative / Null Result ReportOpen accessPhysics
Surachate Limkumnerd · 2026 · arXiv
Fluctuation relations imply the second-law inequality $\langleΣ_T\rangle\ge0$, but path extrema can also constrain how large the mean entropy production can be. For steady-state processes with entropy-production martingale $M_t=e^{-Σ_t}$, we show that knowing only the positive running maximum of $Σ_t$ gives no improvement over the trivial endpoint bound: rare negative entropy-production excursions can still carry the exponential weight required by the fluctuation relation. Using the running extrema $L_T=\inf M_t$ and $H_T=\sup M_t$, we derive a path-extrema upper envelope $\mathcal{U}_{\rm ext
Negative / Null Result ReportOpen accessComputer Science
Zohar Feldman, Carmel Domshlak · 2013 · arXiv
Popular Monte-Carlo tree search (MCTS) algorithms for online planning, such as epsilon-greedy tree search and UCT, aim at rapidly identifying a reasonably good action, but provide rather poor worst-case guarantees on performance improvement over time. In contrast, a recently introduced MCTS algorithm BRUE guarantees exponential-rate improvement over time, yet it is not geared towards identifying reasonably good choices right at the go. We take a stand on the individual strengths of these two classes of algorithms, and show how they can be effectively connected. We then rationalize a principle
Negative / Null Result ReportOpen accessComputer Science
Ravi Shankar Mishra, Kartik Mehta, Nikhil Rasiwasia · 2021 · arXiv
In this paper, we present SANTA, a scalable framework to automatically normalize E-commerce attribute values (e.g. "Win 10 Pro") to a fixed set of pre-defined canonical values (e.g. "Windows 10"). Earlier works on attribute normalization focused on fuzzy string matching (also referred as syntactic matching in this paper). In this work, we first perform an extensive study of nine syntactic matching algorithms and establish that 'cosine' similarity leads to best results, showing 2.7% improvement over commonly used Jaccard index. Next, we argue that string similarity alone is not sufficient for a
Negative / Null Result ReportOpen accessComputer Science
Max Hopkins, Daniel Kane, Shachar Lovett et al. · 2021 · arXiv
The explosive growth of easily-accessible unlabeled data has lead to growing interest in active learning, a paradigm in which data-hungry learning algorithms adaptively select informative examples in order to lower prohibitively expensive labeling costs. Unfortunately, in standard worst-case models of learning, the active setting often provides no improvement over non-adaptive algorithms. To combat this, a series of recent works have considered a model in which the learner may ask enriched queries beyond labels. While such models have seen success in drastically lowering label costs, they tend
Negative / Null Result ReportOpen accessComputer Science
Victor Lagerkvist, Johanna Groven, Leif Eriksson · 2026 · arXiv
The region connection calculus ($RCC$) and Allen's interval algebra ($IA$) are two well-known NP-hard spatial-temporal qualitative reasoning problems. They are solvable in $2^{O(n \log n)}$ time, where $n$ is the number of variables, and $IA$ is additionally known to be solvable in $o(n)^n$ time. However, no improvement over exhaustive search is known for $RCC$, and if they are also solvable in single exponential time $2^{O(n)}$ is unknown. We investigate multiple avenues towards reaching such bounds. First, we show that branching is insufficient since there are too many non-redundant constrai
Negative / Null Result ReportOpen accessMathematics
Shibdas Roy, Ian R. Petersen, Elanor H. Huntington · 2015 · arXiv
We study a coherent-classical estimation scheme for a class of linear quantum systems, where the estimator is a mixed quantum-classical system that may or may not involve coherent feedback. We show that when the quantum plant or the quantum part of the estimator (coherent controller) is an annihilation operator only system, coherent-classical estimation without coherent feedback can provide no improvement over purely-classical estimation. Otherwise, coherent-classical estimation without feedback can be better than classical-only estimation for certain homodyne detector angles, although the for
Negative / Null Result ReportOpen accessPhysics
Md Nahid Haque Shazon, Piyush Kumar, Luqiao Liu et al. · 2025 · arXiv
This paper presents physical modeling and benchmarking for two-terminal spin-orbit torque magnetic random-access memory (2T-SOT-MRAM). The results indicate that the common SOT materials that provide only in-plane torque can provide little to no improvement over spin-transfer-torque (STT) MRAM in terms of write energy. However, emerging SOT materials that provide out-of-plane torques with efficiencies as small as 0.1 can result in significant improvements in the write energy for such 2-terminal devices, especially when the magnet lateral dimensions are scaled down to 30 or 20 nm. Additionally,
Negative / Null Result Report
Claire M. Douglas, Marnie Newell, Susan Goruk et al. · 2025 · PLOS One
Supplementation of omega-3 (n-3) polyunsaturated fatty acids has been associated with reduced side effects and improved quality of life (QoL) in breast cancer patients receiving chemotherapy. The current study reports secondary outcomes…
View details →DOI: 10.1371/journal.pone.0322178 Negative / Null Result Report
Henry Lam · 2025 · Management Science
When the underlying probability distribution in a stochastic optimization is observed only through data, various data-driven formulations have been studied to obtain approximate optimal solutions. We show that no such formulations can, in…
View details →DOI: 10.1287/mnsc.2024.04482 Negative / Null Result ReportOpen accessComputer Science
Elad Hazan, Tomer Koren, Kfir Y. Levy · 2014 · arXiv
The logistic loss function is often advocated in machine learning and statistics as a smooth and strictly convex surrogate for the 0-1 loss. In this paper we investigate the question of whether these smoothness and convexity properties make the logistic loss preferable to other widely considered options such as the hinge loss. We show that in contrast to known asymptotic bounds, as long as the number of prediction/optimization iterations is sub exponential, the logistic loss provides no improvement over a generic non-smooth loss function such as the hinge loss. In particular we show that the c
Abandoned HypothesisOpen accessComputer Science
Kiarn T. Laverick, Howard M. Wiseman, Hossien T. Dinani et al. · 2017 · arXiv
The problem of measuring a time-varying phase, even when the statistics of the variation is known, is considerably harder than that of measuring a constant phase. In particular, the usual bounds on accuracy - such as the $1/(4\bar{n})$ standard quantum limit with coherent states - do not apply. Here, restricting to coherent states, we are able to analytically obtain the achievable accuracy - the equivalent of the standard quantum limit - for a wide class of phase variation. In particular, we consider the case where the phase has Gaussian statistics and a power-law spectrum equal to $κ^{p-1}/|ω
Negative / Null Result ReportOpen accessComputer Science
Shibdas Roy, Ian R. Petersen, Elanor H. Huntington · 2014 · arXiv
We consider a coherent-classical estimation scheme for a class of linear quantum systems. It comprises an estimator that is a mixed quantum-classical system without involving coherent feedback. The estimator yields a classical estimate of a variable for the quantum plant. We demonstrate that for a passive plant that can be characterized by annihilation operators only, such coherent-classical estimation provides no improvement over purely-classical estimation. An example is also given which shows that if the plant is not assumed to be an annihilation operator only quantum system, it is possible
Negative / Null Result ReportOpen accessComputer Science
Reza Fotohi, Mehdi Effatparvar, Fateme Sarkohaki et al. · 2019 · arXiv
Multicore is an integrated circuit chip that uses two or more computational engines (cores) places in a single processor. This new approach is used to split the computational work of a threaded application and spread it over multiple execution cores, so that the computer system can benefits from a better performance and better responsiveness of the system. A thread is a unit of execution inside a process that is created and maintained to execute a set of actions/ instructions. Threads can be implemented differently from an operating system to another, but the operating system is in most cases
Negative / Null Result ReportOpen accessComputer Science
Nandakishore Santhi, Alexander Vardy · 2006 · arXiv
We consider the problem of estimating the probability of error in multi-hypothesis testing when MAP criterion is used. This probability, which is also known as the Bayes risk is an important measure in many communication and information theory problems. In general, the exact Bayes risk can be difficult to obtain. Many upper and lower bounds are known in literature. One such upper bound is the equivocation bound due to Rényi which is of great philosophical interest because it connects the Bayes risk to conditional entropy. Here we give a simple derivation for an improved equivocation bound. We
