Definition:Sigma-Algebra

Also see

 * Equivalence of Definitions of Sigma-Algebra
 * $\sigma$-Algebra as Magma of Sets, proving that $\sigma$-algebras instantiate the general concept of a magma of sets.


 * Sigma-Algebra is Delta-Algebra
 * Delta-Algebra is Sigma-Algebra


 * Definition:Measurable Space: the resulting structure $\struct {X, \Sigma}$