| Optimal Parallel Sequential Change Detection under Generalized Performance Measures Zexian Lu, Yunxiao Chen, Xiaoou Li | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Optimal portfolio selection and compression in an incomplete market Nikolai Dokuchaev, Ulrich Haussmann | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Optimal probabilistic forecasts for risk management Yuru Sun, Worapree Maneesoonthorn, Ruben Loaiza-Maya | L4–5 Advanced | CC-BY-NC-ND | mirrored | 29 pp. | arxiv |
| Optimal Regulation of Prosumers and Consumers in Smart Energy Communities Syed Eqbal Alam, Dhirendra Shukla | L4–5 Advanced | CC-BY | mirrored | 9 pp. | arxiv |
| Optimal Robust Mechanism in Bilateral Trading Komal Malik | L4–5 Advanced | CC-BY-NC-ND | mirrored | 48 pp. | arxiv |
| Optimal scheduling of island integrated energy systems considering multi-uncertainties and hydrothermal simultaneous transmission: A deep reinforcement learning approach Yang Li, Fanjin Bu, Yuanzheng Li | L4–5 Advanced | CC-BY-NC-ND | mirrored | 25 pp. | arxiv |
| Optimal social security timing A. Y. Aydemir | L4–5 Advanced | CC-BY | mirrored | 21 pp. | arxiv |
| Optimal solution of investment problems via linear parabolic equations generated by Kalman filter Nikolai Dokuchaev | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Optimal stable Ornstein-Uhlenbeck regression Hiroki Masuda | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Optimal subsampling algorithm for composite quantile regression with distributed data Xiaohui Yuan, Shiting Zhou, Yue Wang | L4–5 Advanced | CC-BY | mirrored | 29 pp. | arxiv |
| Optimal Time to Sell a Stock in Black-Scholes Model: Comment on "Thou shall buy and hold", by A. Shiryaev, Z. Xu and X.Y. Zhou Satya N. Majumdar, Jean-Philippe Bouchaud | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Optimal transport with $f$-divergence regularization and generalized Sinkhorn algorithm D\'avid Terj\'ek (1), Diego Gonz\'alez-S\'anchez (1) ((1) Alfr\'ed R\'enyi Institute of Mathematics) | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Optimization of Image Transmission in a Cooperative Semantic Communication Networks Wenjing Zhang, Yining Wang, Mingzhe Chen | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Option pricing under stochastic volatility: the exponential Ornstein-Uhlenbeck model Josep Perello, Ronnie Sircar, Jaume Masoliver | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Option pricing under the normal SABR model with Gaussian quadratures Jaehyuk Choi, Byoung Ki Seo | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Option pricing with fractional volatility Rui Vilela Mendes, Maria Joao Oliveira | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Option Pricing without Price Dynamics: A Probabilistic Approach Dimitris Bertsimas, Natasha Bushueva | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Oracle Complexity and Nontransitivity in Pattern Recognition Vadim Bulitko | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Orbital order in classical models of transition-metal compounds Zohar Nussinov, Marek Biskup, Lincoln Chayes | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Orbital ordering in transition-metal compounds: I. The 120-degree model Marek Biskup, Lincoln Chayes, Zohar Nussinov | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Order book regulatory impact on stock market quality: a multi-agent reinforcement learning perspective Johann Lussange, Boris Gutkin | L4–5 Advanced | CC-BY | mirrored | 21 pp. | arxiv |
| Ordering-based Representations of Rational Inference Konstantinos Georgatos | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Order patterns, their variation and change points in financial time series and Brownian motion Christoph Bandt | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Organic Chemistry Wade Textmap | L1–3 Foundational | CC-BY-NC-SA | mirrored | 1,428 pp. | libretexts |
| Organic Chemistry Wade Textmap | L1–3 Foundational | CC-BY-NC-SA | mirrored | 1,435 pp. | libretexts |
| Organic Chemistry: A Tenth Edition | L1–2 Foundational | CC-BY-NC-SA | mirrored | 1,245 pp. | openstax |
| Organizational Behavior LibreTexts | L1–3 Foundational | CC-BY-NC-SA-3.0 | mirrored | 513 pp. | libretexts |
| Organizational Behavior | L1–2 Foundational | CC-BY-NC-SA | mirrored | 631 pp. | openstax |
| Organon (Owen) | L2–5 Introductory | Public domain | mirrored | 599 pp. | wikisource |
| Orthogonal Policy Learning Under Ambiguity Riccardo D'Adamo | L4–5 Advanced | CC-BY | mirrored | 49 pp. | arxiv |
| Out-Of-Distribution Generalization on Graphs: A Survey Haoyang Li, Xin Wang, Ziwei Zhang | L4–5 Advanced | CC-BY-NC-SA | mirrored | 20 pp. | arxiv |
| PAC-Bayesian-Like Error Bound for a Class of Linear Time-Invariant Stochastic State-Space Models Deividas Eringis, John Leth, Zheng-Hua Tan | L4–5 Advanced | CC-BY-NC-SA | mirrored | 36 pp. | arxiv |
| p-adic vertex operator algebras Cameron Franc, Geoffrey Mason | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Pain or Anxiety? The Health Consequences of Rising Robot Adoption in China Qiren Liu, Sen Luo, Robert Seamans | L4–5 Advanced | CC-BY | mirrored | 22 pp. | arxiv |
| Pairwise interaction function estimation of Gibbs point processes using basis expansion Isma\"ila Ba, Jean-Fran\c{c}ois Coeurjolly, Francisco Cuevas-Pacheco | L4–5 Advanced | CC-BY | mirrored | 45 pp. | arxiv |
| PAL: Pertinence Action Language Pedro Cabalar, Manuel Cabarcos, Ramon P. Otero | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Panacea or Placebo? Exploring Causal Effects of Nonlocal Vehicle Driving Restriction Policies on Traffic Congestion Using Difference-in-differences Approach Yuan Liang, Quan Yuan, Daoge Wang | L4–5 Advanced | CC-BY | mirrored | 35 pp. | arxiv |
| Parallel Connections Over Symmetric Spaces Luis Guijarro, Lorenzo Sadun, Gerard Walschap | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parallel Strands: A Preliminary Investigation into Mining the Web for Bilingual Text Philip Resnik (University of Maryland) | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parallel Tempering With a Variational Reference Nikola Surjanovic, Saifuddin Syed, Alexandre Bouchard-C\^ot\'e | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Parameter-free Model of Rank Polysemantic Distribution Victor Kromer | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parametric and nonparametric models and methods in financial econometrics Zhibiao Zhao | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parametric Differential Machine Learning for Pricing and Calibration Arun Kumar Polala, Bernhard Hientzsch | L4–5 Advanced | arxiv-nonexclusive | link only | — | arxiv |
| Pareto's law: a model of human sharing and creativity Nicola Scafetta, Sergio Picozzi, Bruce J. West | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Pareto's Law for Income of Individuals and Debt of Bankrupt Companies Hideaki Aoyama, Yuichi Nagahara, Mitsuhiro P. Okazaki | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parsing Inside-Out Joshua Goodman (Harvard University) | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parsing syllables: modeling OT computationally Michael Hammond (University of Arizona) | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Parsing with the Shortest Derivation Rens Bod | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Partial Derivative Approach for Option Pricing in a Simple Stochastic Volatility Model Miquel Montero | L4–5 Advanced | Licence unknown | link only | — | arxiv |
| Partial Evaluation for Efficient Access to Inheritance Lexicons Sven Hartrumpf (University of Hagen, Germany) | L4–5 Advanced | Licence unknown | link only | — | arxiv |