Direct Sum (Module)
The direct sum of two Modules 
and 
over the same Ring 
is given by 
with Module operations defined by
The direct sum of an arbitrary family of Modules over the same Ring is also defined. If
is theindexing set for the family of Modules, then the direct sum is represented by the collection of functionswith finite support from to the union of all these Modules such that the function sends 
to anelement in the Module indexed by 
.The dimension of a direct sum is the product of the dimensions of the quantities summed. The significant property of thedirect sum is that it is the coproduct in the category of Modules. This general definition gives as aconsequence the definition of the direct sum of Abelian Groups (since they areModules over the Integers) and the direct sum of Vector Spaces(since they are Modules over a Field).
- Centillion
- Central Angle
- Central Beta Function
- Central Binomial Coefficient
- Central Conic
- Central Difference
- Centralizer
- Central Limit Theorem
- Central Trinomial Coefficient
- Centrode
- Centroid (Function)
- Centroid (Geometric)
- Centroid (Orthocentric System)
- Centroid (Triangle)
- Certificate of Compositeness
- Certificate of Primality
- Cesàro Equation
- Cesàro Fractal
- Cesàro Mean
- Ceva's Theorem
- Cevian
- Cevian Conjugate Point
- Cevian Transform
- Cevian Triangle
- Chain