Betti Number
Betti numbers are topological objects which were proved to be invariants by Poincaré, 
and usedby him to extend the Polyhedral Formula to higher dimensional spaces. The 
th Betti number is the rank of theth Homology Group. Let 
be the Rank of the Homology Group 
of aTopological Space 
. For a closed, orientable surface of Genus 
, the Betti numbers are 
,
, and 
. For a nonorientable surface with 
Cross-Caps, the Betti numbers are, 
, and 
.
- Weak Law of Large Numbers
- Weakly Binary Tree
- Weakly Complete Sequence
- Weakly Independent
- Weakly Triple-Free Set
- Weber Differential Equations
- Weber Functions
- Weber's Discontinuous Integrals
- Weber's Formula
- Weber-Sonine Formula
- Weber's Theorem
- Web Graph
- Wedderburn's Theorem
- Weddle's Rule
- Wedge
- Wedge Product
- Weekday
- Weibull Distribution
- Weierstrass M-Test
- Weierstraß Approximation Theorem
- Weierstraß-Casorati Theorem
- Weierstraß Constant
- Weierstraß Elliptic Function
- Weierstraß-Erdman Corner Condition
- Weierstraß Extreme Value Theorem