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Identity Element

The identity element $I$ (also denoted $E$, $e$, or $1$) of a Group or related mathematical structure $S$ is the unique elements such that $IA=AI=A$ for every element $A\in S$. The symbol ``$E$'' derives from the German word for unity, ``Einheit.''

See also Binary Operator, Group, Involution (Group), Monoid

© 1996-9 Eric W. Weisstein