Wikipedia:WikiProject Mathematics/List of mathematics articles (O)

O
O-minimal theory  -- O'Brien code I  -- O'Brien code II  -- O'Nan group  -- O'Nan–Scott theorem  -- O(n)  -- O*-algebra  -- Obconic  -- Oberwolfach problem  -- Object language  -- Object of the mind  -- Object theory  -- Oblate spheroidal coordinates  -- Oblate spheroidal wave function  -- Oblique lattice  -- Oblique projection  -- Oblique reflection  -- Observability  -- Observability Gramian  -- Observable subgroup  -- Observable variable  -- Observational equivalence  -- Observational error  -- Observational study  -- Obstacle avoidance  -- Obstacle problem  -- Obstruction theory  -- Obversion  -- Occam's razor  -- Occupancy frequency distribution  -- Occupancy theorem  -- Occurrences of Grandi's series  -- Occurs check  --

Oce
Ocean general circulation model  -- Ockham algebra  -- Octacontagon  -- Octacube (sculpture)  -- Octadecagon  -- Octadecahedron  -- Octagon  -- Octagonal antiprism  -- Octagonal bipyramid  -- Octagonal number  -- Octagonal prism  -- Octagonal trapezohedron  -- Octagram  -- Octagrammic antiprism  -- Octagrammic crossed-antiprism  -- Octagrammic cupola  -- Octagrammic prism  -- Octahedral cupola  -- Octahedral-dodecahedral honeycomb  -- Octahedral-hexagonal tiling honeycomb  -- Octahedral number  -- Octahedral prism  -- Octahedral pyramid  -- Octahedral symmetry  -- Octahedron  -- Octahemioctahedron  -- Octal  -- Octal game  -- Octal games  -- Octant (solid geometry)  -- Octave (electronics)  -- Octic reciprocity  -- Octomino  -- Octonion  -- Octonion algebra  --

Odd
Odd cycle transversal  -- Odd graph  -- Odd greedy expansion  -- Odd number  -- Odd number theorem  -- Odd Squad  -- Odds  -- Odds algorithm  -- Odds and evens  -- Odds and evens (hand game)  -- Odds ratio  -- Odia numerals  -- Odious number  -- Odlyzko–Schönhage algorithm  -- Of the form  -- Offered load  -- Official statistics  -- Offset binary  -- Ogden's lemma  -- Ogg's formula  -- Ogive  -- Ogive (statistics)  -- Ohlson O-score  -- Ohsawa–Takegoshi L2 extension theorem  -- Oka coherence theorem  -- Oka–Weil theorem  -- Oka's lemma  -- Okishio's theorem  -- Okubo algebra  -- Olaf Storaasli  -- Olami–Feder–Christensen model  --

Olb
Olbers' paradox  -- Olech theorem  -- OLGA (technology)  -- Olimpíada Brasileira de Matemática  -- Olimpíada Brasileira de Matemática das Escolas Públicas  -- Olimpíada de Matemática do Grande ABC  -- Oliver Sin  -- Olog  -- Oloid  -- Olympiade Mathématique Belge  -- OMDoc  -- Omega and agemo subgroup  -- Omega-categorical theory  -- Omega constant  -- Omega equation  -- Omega function  -- Omega-logic  -- Omega ratio  -- Omitted-variable bias  -- Omnibus test  -- Omnitruncated 5-simplex honeycomb  -- Omnitruncated 6-simplex honeycomb  -- Omnitruncated 7-simplex honeycomb  -- Omnitruncated 8-simplex honeycomb  -- Omnitruncated polyhedron  -- Omnitruncated simplectic honeycomb  -- Omnitruncated tesseractic honeycomb  -- Omnitruncation  -- On Conoids and Spheroids  -- On Formally Undecidable Propositions of Principia Mathematica and Related Systems  -- On-Line Encyclopedia of Integer Sequences  -- On Numbers and Games  -- On Sizes and Distances (Hipparchus)  -- On Spirals  -- On the Number of Primes Less Than a Given Magnitude  -- On the Sphere and Cylinder  --

One
One- and two-tailed tests  -- One-dimensional space  -- One-dimensional symmetry group  -- One-form (differential geometry)  -- One half  -- One in ten rule  -- One-key MAC  -- One-parameter group  -- One-relator group  -- One-seventh area triangle  -- One-shot deviation principle  -- One-sided limit  -- One Through Zero (The Ten Numbers)  -- One-way analysis of variance  -- One-way function  -- One-way wave equation  -- Ones' complement  -- Online codes  -- Online optimization  -- Ono's inequality  -- Onsager–Machlup function  -- Onsager reciprocal relations  -- Ontario Mathematics Olympiad  -- Ontological maximalism  -- Opaque set  -- Opasnet  -- Open and closed maps  -- Open assessment  -- Open book decomposition  -- Open coloring axiom  -- Open Energy Modelling Initiative  -- Open energy system models  -- Open formula  -- Open-loop model  -- Open mapping theorem  -- Open mapping theorem (complex analysis)  -- Open mapping theorem (functional analysis)  -- Open Mathematics  -- Open problem  -- Open Problems in Mathematics  -- Open set  -- Open set condition  -- Open-shop scheduling  -- Open Systems & Information Dynamics  -- OpenBLAS  -- OpenIntro Statistics  -- OpenMath  -- OpenPlaG  -- Oper (mathematics)  -- Opera Omnia Leonhard Euler  -- Operad  -- Operad algebra  -- Operand  -- Operation (mathematics)  -- Operational calculus  -- Operational Research Society  -- Operations research  -- Operations Research (journal)  -- Operations Research Society of South Africa  -- Operator  -- Operator (mathematics)  -- Operator (physics)  -- Operator algebra  -- Operator associativity  -- Operator ideal  -- Operator K-theory  -- Operator monotone function  -- Operator norm  -- Operator space  -- Operator system  -- Operator theory  -- Operator topologies  -- Opetope  --

Opi
Opial property  -- Opinion poll  -- Opinion polling in the Philippine Senate election, 2010  -- Oppenheim conjecture  -- Oppermann's conjecture  -- Opposite  -- Opposite category  -- Opposite group  -- Opposite ring  -- Optic equation  -- Optical axis  -- Optical chaos  -- Optical correlator  -- Opticks  -- Optimal apportionment  -- Optimal computing budget allocation  -- Optimal control  -- Optimal design  -- Optimal discriminant analysis  -- Optimal estimation  -- Optimal instruments  -- Optimal matching  -- Optimal projection equations  -- Optimal stopping  -- Optimal substructure  -- Optimality criterion  -- Optimistic knowledge gradient  -- Optimization (computer science)  -- OptimJ  -- Option on realized variance  -- Option on realized volatility  -- Optional stopping theorem  -- Options strategy  --

Opu
Opuscula Mathematica  -- OR gate  -- Oracle complexity (optimization)  -- Oracle machine  -- Orbifold  -- Orbifold notation  -- Orbit (dynamics)  -- Orbit capacity  -- Orbit method  -- Orbit modeling  -- Orbit portrait  -- Orbit trap  -- Orbital integral  -- Orbital momentum vector  -- Orbital overlap  -- Orbital stability  -- Orbital state vectors  -- Orbital velocity  -- Orchard-planting problem  -- Order (graph theory)  -- Order (group theory)  -- Order (journal)  -- Order (mathematics)  -- Order (number theory)  -- Order (ring theory)  -- Order-2 apeirogonal tiling  -- Order-3-4 heptagonal honeycomb  -- Order-3-5 heptagonal honeycomb  -- Order-3-6 heptagonal honeycomb  -- Order-3-7 heptagonal honeycomb  -- Order-3-7 hexagonal honeycomb  -- Order 3-7 kisrhombille  -- Order-4 120-cell honeycomb  -- Order-4 24-cell honeycomb  -- Order-4 24-cell honeycomb honeycomb  -- Order-4-3 pentagonal honeycomb  -- Order-4-4 pentagonal honeycomb  -- Order-4-5 pentagonal honeycomb  -- Order-4-5 square honeycomb  -- Order-4 dodecahedral honeycomb  -- Order-4 heptagonal tiling  -- Order-4 hexagonal tiling honeycomb  -- Order-4 icosahedral honeycomb  -- Order-4 octahedral honeycomb  -- Order-4 pentagonal tiling  -- Order-4 square hosohedral honeycomb  -- Order-4 square tiling honeycomb  -- Order-5 120-cell honeycomb  -- Order-5-3 square honeycomb  -- Order-5-4 square honeycomb  -- Order-5 5-cell honeycomb  -- Order-5 cubic honeycomb  -- Order-5 dodecahedral honeycomb  -- Order-5 hexagonal tiling honeycomb  -- Order-5 icosahedral 120-cell honeycomb  -- Order-5 octahedral honeycomb  -- Order-5 pentagonal tiling  -- Order-5 square tiling  -- Order-5 tesseractic honeycomb  -- Order-5 truncated pentagonal hexecontahedron  -- Order-6-3 square honeycomb  -- Order-6-4 square honeycomb  -- Order-6-4 triangular honeycomb  -- Order-6 cubic honeycomb  -- Order-6 dodecahedral honeycomb  -- Order-6 hexagonal tiling honeycomb  -- Order-6 tetrahedral honeycomb  -- Order-6 triangular hosohedral honeycomb  -- Order-7-3 triangular honeycomb  -- Order-7 cubic honeycomb  -- Order-7 dodecahedral honeycomb  -- Order-7 heptagonal tiling  -- Order-7 heptagrammic tiling  -- Order-7 square tiling  -- Order-7 tetrahedral honeycomb  -- Order-7 triangular tiling  -- Order-7 truncated triangular tiling  -- Order-8-3 triangular honeycomb  -- Order and Chaos  -- Order bound dual  -- Order complete  -- Order convergence  -- Order dimension  -- Order dual (functional analysis)  -- Order embedding  -- Order-extension principle  -- Order-infinite-3 triangular honeycomb  -- Order isomorphism  -- Order of a kernel  -- Order of a polynomial  -- Order of accuracy  -- Order of approximation  -- Order of integration (calculus)  -- Order of magnitude  -- Order of operations  -- Order polynomial  -- Order polytope  -- Order statistic  -- Order summable  -- Order theory  -- Order topology  -- Order topology (functional analysis)  -- Order type  -- Order unit  -- Order-zero graph  -- Ordered algebra  -- Ordered Bell number  -- Ordered exponential  -- Ordered exponential field  -- Ordered field  -- Ordered geometry  -- Ordered graph  -- Ordered logit  -- Ordered pair  -- Ordered probit  -- Ordered ring  -- Ordered semigroup  -- Ordered set  -- Ordered set operators  -- Ordered subset expectation maximization  -- Ordered topological vector space  -- Ordered vector space  -- Orders of magnitude (probability)  -- Ordinal analysis  -- Ordinal arithmetic  -- Ordinal association  -- Ordinal collapsing function  -- Ordinal date  -- Ordinal definable set  -- Ordinal logic  -- Ordinal notation  -- Ordinal number  -- Ordinal numeral  -- Ordinal numerical competence  -- Ordinal Priority Approach  -- Ordinal regression  -- Ordinal sum  -- Ordinary differential equation  -- Ordinary least squares  -- Ordinary singularity  -- Ordination (statistics)  --

Ore
Ore algebra  -- Ore condition  -- Ore extension  -- Ore's theorem  -- Oregonator  -- Organon  -- Orientability  -- Orientation (geometry)  -- Orientation (graph theory)  -- Orientation (vector space)  -- Orientation character  -- Orientation entanglement  -- Orientation of a vector bundle  -- Orientation sheaf  -- Oriented coloring  -- Oriented matroid  -- Oriented projective geometry  -- Orientifold  -- Origami Polyhedra Design  -- Origamics  -- Origin (mathematics)  -- Original proof of Gödel's completeness theorem  -- Orlicz–Pettis theorem  -- Orlicz sequence space  -- Orlicz space  -- Ornstein isomorphism theorem  -- Ornstein–Uhlenbeck operator  -- Ornstein–Uhlenbeck process  -- Ornstein–Zernike equation  -- Orr–Sommerfeld equation  --

Ort
Orthant  -- Orthobifastigium  -- Orthocentric system  -- Orthocentric tetrahedron  -- Orthocentroidal circle  -- Orthocompact space  -- Orthodiagonal quadrilateral  -- Orthodox semigroup  -- Orthogonal array  -- Orthogonal basis  -- Orthogonal complement  -- Orthogonal convex hull  -- Orthogonal coordinates  -- Orthogonal diagonalization  -- Orthogonal functions  -- Orthogonal group  -- Orthogonal matrix  -- Orthogonal polynomials  -- Orthogonal polynomials on the unit circle  -- Orthogonal Procrustes problem  -- Orthogonal symmetric Lie algebra  -- Orthogonal trajectory  -- Orthogonal transformation  -- Orthogonal wavelet  -- Orthogonality  -- Orthogonality (mathematics)  -- Orthogonality (term rewriting)  -- Orthogonality principle  -- Orthogonalization  -- Orthographic projection  -- Orthographic projection (cartography)  -- Orthologic triangles  -- Orthometric height  -- Orthomorphism  -- Orthonormal basis  -- Orthonormal frame  -- Orthonormal function system  -- Orthonormality  -- Orthopole  -- Orthoptic (geometry)  -- Orthostochastic matrix  --

Osc
Oscillation  -- Oscillation (mathematics)  -- Oscillation theory  -- Oscillator linewidth  -- Oscillator representation  -- Oscillatory integral  -- Oscillatory integral operator  -- Oscillon  -- Osculant  -- Osculate  -- Osculating circle  -- Osculating curve  -- Osculating plane  -- Oseen equations  -- Oseledets theorem  -- Osgood curve  -- Osgood's lemma  -- Osmund Lewry  -- Ostomachion  -- Ostrogradsky instability  -- Ostrowski–Hadamard gap theorem  -- Ostrowski numeration  -- Ostrowski Prize  -- Ostrowski's theorem  -- Oswald Veblen Prize in Geometry  -- Otis King  -- Otsu's method  -- Out in Science, Technology, Engineering, and Mathematics  -- Out-of-bag error  -- Out-of-kilter algorithm  -- Out to Innovate  -- Out(Fn)  -- Outage probability  -- Outcome (game theory)  -- Outcome (probability)  -- Outer automorphism group  -- Outer billiards  -- Outer measure  -- Outer product  -- Outer space (mathematics)  -- Outermorphism  -- Outerplanar graph  -- Outlier  -- Outline of algebra  -- Outline of algebraic structures  -- Outline of arithmetic  -- Outline of calculus  -- Outline of category theory  -- Outline of combinatorics  -- Outline of discrete mathematics  -- Outline of geometry  -- Outline of linear algebra  -- Outline of logic  -- Outline of mathematics  -- Outline of probability  -- Outline of regression analysis  -- Outline of statistics  -- Outline of trigonometry  --

Ova
Oval  -- Oval (projective plane)  -- Overcategory  -- Overcompleteness  -- Overconvergent modular form  -- Overdetermined system  -- Overdispersion  -- Overfitting  -- Overfull conjecture  -- Overfull graph  -- Overlap (term rewriting)  -- Overlap–add method  -- Overlap coefficient  -- Overlap–save method  -- Overlapping circles grid  -- Overlapping interval topology  -- Overlapping subproblems  -- Overring  -- Oversampling and undersampling in data analysis  -- Overspill  -- Ovoid (polar space)  -- Ovoid (projective geometry)  -- Owen's T function  -- Oxford Set of Mathematical Instruments  --