Anarboricity
Given a Graph 
, the anarboricity is the maximum number of line-disjoint nonacyclicSubgraphs whose Union is .
- Oscillation Land
- Osculating Circle
- Osculating Curves
- Osculating Interpolation
- Osculating Plane
- Osculating Sphere
- Osedelec Theorem
- Ostrowski's Inequality
- Ostrowski's Theorem
- Otter's Tree Enumeration Constants
- Outdegree
- Outer Automorphism Group
- Outer Product
- Oval
- Oval of Descartes
- Ovals of Cassini
- Overlapping Resonance Method
- Oversampling
- Ovoid
- Paasche's Index
- Packing
- Packing Density
- p-adic Number
- Padovan Sequence
- Padé Approximant