---
tag: G4T9WYV7BJ
kind: concept
name: 'Sqb2:'
sources:
  - wikipedia: en:73634@r1376316324
    locator: Glossary of mathematical symbols, section Brackets > Square brackets
    note: adopted
    mention: wikipedia://en/73634#8RL7
    sections: [Summary]
inventory: [XBD3KE0KWW]
---

## Summary

[[Degree of a field extension|0EAJ2XXADC]]: if $F$ is an extension of a [[field|04C5ZBG1WT]] $E$, then $[F:E]$ denotes the degree of the [[field extension|0EQWVHF3W5]] $F/E$. For example, $[\mathbb C:\mathbb R]=2$.

[[Index of a subgroup|0DTXBQPA2S]]: if $H$ is a [[subgroup|0X1JXT47GA]] of a group $E$, then $[G:H]$ denotes the index of $H$ in $G$. The notation $\lvert G:H\rvert$ is also used.