Set Partition
A set partition of a Set 
is a collection of disjoint Subsets of whose Union is . The number of partitions of the Set 
is called a Bell Number.
References
Ruskey, F. ``Info About Set Partitions.'' http://sue.csc.uvic.ca/~cos/inf/setp/SetPartitions.html.
- Identity Map
- Identity Matrix
- Identity Operator
- Idoneal Number
- Iff
- Ill-Conditioned
- Illumination Problem
- Illusion
- Image
- Imaginary Identity
- Imaginary Number
- Imaginary Part
- Imaginary Point
- Imaginary Quadratic Field
- Immanant
- Immersed Minimal Surface
- Immersion
- Impartial Game
- Implicit Function
- Implicit Function Theorem
- Implies
- Impossible Figure
- Impredicative
- Improper Integral
- Improper Node