---
tag: NMB6AXJCZ4
kind: concept
name: Bicommutant
aliases: [double-commutant]
sources:
  - wikipedia: en:455964@r1354564322
    locator: Bicommutant
    note: adopted
    mention: wikipedia://en/455964
    sections: [Summary]
same_as:
  wikidata: Q2901650
  wikipedia: Bicommutant
inventory: [JQDN32JB7F]
---

## Summary

In algebra, the **bicommutant** of a [[subset|0BJR9QR08E]] *S* of a [[semigroup|0XMEM406JM]] (such as an algebra or a group) is the commutant of the commutant of that subset. It is also known as the double commutant or second commutant and is written $S^{\prime \prime}$.