Atom of a sigma-algebra
= Atom of a sigma-algebra
A sigma-algebra atom is set-theoretically minimal. An <atom (measure theory)> is instead indivisible only modulo sets of measure zero.
An atom of a sigma-algebra is a nonempty measurable set containing no proper nonempty measurable subset. A finite sigma-algebra partitions its underlying set into atoms, and each measurable set is a union of them.