Rank (Group)
For an arbitrary finitely generated Abelian Group 
, the rank of is defined to be the rank of the Freegenerating Subset modulo its Torsion Subgroup. For a finitely generatedGroup, the rank is defined to be the rank of its ``Abelianization.''
- Unknotting Number
- Unless
- Unlesss
- Unmixed
- Unpoke Move
- Unsafe
- Unsolved Problem
- Unstable Improper Node
- Unstable Node
- Unstable Spiral Point
- Unstable Star
- Untouchable Number
- U-Number
- Upper Bound
- Upper Integral
- Upper Limit
- Upper Sum
- Upper-Trimmed Subsequence
- Upward Drawing
- Urchin
- Utility Graph
- Utility Problem
- Valence
- Valency
- Valuation