Invertible

In mathematics one calls invertible :

• a function whose inverse function exists
• an element of a semigroup with a neutral element for which there is one such that . ${\displaystyle a}$ ${\displaystyle H}$ ${\displaystyle e}$ ${\displaystyle b\in H}$ ${\displaystyle ab=ba=e}$
• an element of a ring with one element 1 for which there is a such that . ${\displaystyle a}$ ${\displaystyle R}$ ${\displaystyle b\in R}$ ${\displaystyle ab=ba=1}$
  • a regular matrix as a special case

This is a disambiguation page for differentiating between several terms identified with the same word.