| ObjectSeeker: Certifiably Robust Object Detection against Patch Hiding Attacks via Patch-agnostic Masking Chong Xiang, Alexander Valtchanov, Saeed Mahloujifar | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Observers for Differential Algebraic Equation Models of Power Networks: Jointly Estimating Dynamic and Algebraic States Sebastian Nugroho, Ahmad Taha, Nikolaos Gatsis | L4–5 Advanced | CC-BY | mirrored | 13 pp. | arxiv |
| Occam factors and model-independent Bayesian learning of continuous distributions Ilya Nemenman, William Bialek | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Ocular dominance patterns in mammalian visual cortex: A wire length minimization approach Dmitri B. Chklovskii, Alexei A. Koulakov | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Odd and even Fibonacci lattices arising from a Garside monoid Thomas Gobet, Baptiste Rognerud | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| OER 101: Introduction to OER AJ Barse, Justina Brown | L1–3 Foundational | CC-BY | mirrored | 58 pp. | libretexts |
| Off-Balance Sheet Activities and Scope Economies in U.S. Banking Jingfang Zhang, Emir Malikov | L4–5 Advanced | CC-BY | mirrored | 32 pp. | arxiv |
| Offline Policy Optimization in RL with Variance Regularizaton Riashat Islam, Samarth Sinha, Homanga Bharadhwaj | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Offline Reinforcement Learning with Differential Privacy Dan Qiao, Yu-Xiang Wang | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Of the Conduct of the Understanding | L2–5 Introductory | Public domain | mirrored | 132 pp. | wikisource |
| On a cepstrum-based speech detector robust to white noise Sergei Skorik, Frederic Berthommier | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On a class of closed cocycles for algebras of non-formal, possibly unbounded, pseudodifferential operators Jean-Pierre Magnot | L4–5 Advanced | CC-BY | mirrored | 10 pp. | arxiv |
| On a class of stochastic differential equations used in quantum optics Alberto Barchielli (Dipartimento di Matematica - Politecnico di Milano), Fabio Zucca (Dipartimento di Matematica - Universita` degli Studi di Milano) | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On a conjecture of Bitoun and Schedler Mircea Mustata, Sebastian Olano | L4–5 Advanced | CC-BY | mirrored | 14 pp. | arxiv |
| On a conjecture of Lange B. Russo, M. Teixidor i Bigas | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On a Cyclic Inequality Related to Chebyshev Polynomials Mohammad Javaheri, Harry Shen | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On a determinant formula for some real regular representations L\'ea Bittmann | L4–5 Advanced | CC-BY | mirrored | 21 pp. | arxiv |
| On a generalised model for time-dependent variance with long-term memory Silvio M. Duarte Queiros | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On Agents' Agreement and Partial-Equilibrium Pricing in Incomplete Markets Michail Anthropelos, Gordan Zitkovic | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Almost Orthogonal Series Ruiming Zhang | L4–5 Advanced | CC-BY | mirrored | 22 pp. | arxiv |
| On an analytical method for the satellite problem revisited Claudio Saccon, Niccol\`o Pilloni | L4–5 Advanced | CC-BY | mirrored | 13 pp. | arxiv |
| On anomalous distributions in intra-day financial time series and Non-extensive Statistical Mechanics Silvio M. Duarte Queiros | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On a Non-Standard Stochastic Control Problem Ivar Ekeland, Traian A Pirvu | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Automata with Boundary R. Gates, P. Katis, N. Sabadini | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On Blockchain We Cooperate: An Evolutionary Game Perspective Luyao Zhang, Xinyu Tian | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Bochner's Almost-periodicity criterion Philippe Cieutat | L4–5 Advanced | CC-BY | mirrored | 14 pp. | arxiv |
| On certain generalized notions using $\mathcal{I}$-convergence in topological spaces Pratulananda Das, Upasana Samanta, Shou Lin | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Classes of Functions for which No Free Lunch Results Hold Christian Igel, Marc Toussaint | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On classical and Bayesian inference for bivariate Poisson conditionals distributions: Theory, methods and applications Barry C. Arnold, Indranil Ghosh | L4–5 Advanced | CC-BY | mirrored | 20 pp. | arxiv |
| On common index divisor of the number fields defined by $x^7+ax+b$ Anuj Jakhar, Sumandeep Kaur, Surender Kumar | L4–5 Advanced | CC-BY | mirrored | 16 pp. | arxiv |
| On Deep Recurrent Reinforcement Learning for Active Visual Tracking of Space Noncooperative Objects Dong Zhou, Guanghui Sun, Zhao Zhang | L4–5 Advanced | CC-BY-NC-SA | mirrored | 7 pp. | arxiv |
| On Deligne's conjecture for symmetric fourth $L$-functions of Hilbert modular forms Shih-Yu Chen | L4–5 Advanced | CC-BY-NC-ND | mirrored | 51 pp. | arxiv |
| On Differential Privacy and Traffic State Estimation Problem for Connected Vehicles Suyash C. Vishnoi, Ahmad F. Taha, Sebastian A. Nugroho | L4–5 Advanced | CC0-1.0 | mirrored | 7 pp. | arxiv |
| One Bad Apple Spoils the Barrel: Understanding the Security Risks Introduced by Third-Party Components in IoT Firmware Binbin Zhao, Shouling Ji, Jiacheng Xu | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| OneFormer: One Transformer to Rule Universal Image Segmentation Jitesh Jain, Jiachen Li, MangTik Chiu | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Equilibrium Prices in Continuous Time V. Filipe Martins-da-Rocha, Frank Riedel | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| One Sense per Collocation and Genre/Topic Variations David Martinez, Eneko Agirre | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On Existence Theorems for Conditional Inferential Models Rongrong Zhang, Michael Y. Zhu, Chuanhai Liu | L4–5 Advanced | CC-BY-NC-ND | mirrored | 26 pp. | arxiv |
| On Exponential-Time Completeness of the Circularity Problem for Attribute Grammars Pei-Chi Wu | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On finitely nondegenerate closed homogeneous CR manifolds Stefano Marini, Costantino Medori, Mauro Nacinovich | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Frequency-Based Optimal Portfolio with Transaction Costs Chung-Han Hsieh, Yi-Shan Wong | L4–5 Advanced | CC-BY | mirrored | 31 pp. | arxiv |
| On Geodesics of Sprays and Projective Completeness Guojun Yang | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On geometry behind Birkhoff theorem Pavol Severa | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On Hawkes Processes with Infinite Mean Intensity Cecilia Aubrun, Michael Benzaquen, Jean-Philippe Bouchaud | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Heyting algebras with negative tense operators F. Almi\~nana, G. Pelaitay, W. Zuluaga | L4–5 Advanced | CC-BY | mirrored | 22 pp. | arxiv |
| On High dimensional Poisson models with measurement error: hypothesis testing for nonlinear nonconvex optimization Fei Jiang, Yeqing Zhou, Jianxuan Liu | L4–5 Advanced | CC-BY | mirrored | 78 pp. | arxiv |
| On higher order embeddings of Fano threefolds by the anticanonical linear system M. C. Beltrametti, S. Di Rocco, A. J. Sommese | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| On Korobov bound concerning Zaremba's conjecture Nikolay Moshchevitin, Brendan Murphy, Ilya Shkredov | L4–5 Advanced | CC-BY | mirrored | 25 pp. | arxiv |
| On large differences between consecutive primes Olli J\"arviniemi | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| On Learning the Structure of Clusters in Graphs Peter Macgregor | L4–5 Advanced | CC-BY | mirrored | 164 pp. | arxiv |