Identity Element

The identity element I (also denoted E, e, or 1) of a group or related mathematical structure S is the unique element such that Ia=aI=a for every element a in S. The symbol "E" derives from the German word for unity, "Einheit." An identity element is also called a unit element.

See also

Binary Operator, Group, Group Involution, Monoid

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Cite this as:

Weisstein, Eric W. "Identity Element." From MathWorld--A Wolfram Web Resource.

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