| 释义 |
identity (identity element) An element e is an identity element (or neutral element) for a binary operation ∘ on a set S if, for all a in S, a ∘ e = e ∘ a = a. In a group, the identity element is commonly denoted e. In a ring, the additive identity is denoted 0 and referred to as ‘zero' and the multiplicative identity (if it exists) is denoted 1 and referred to as ‘one'. Even though the numerical symbols ‘0' and ‘1' are used, 0 may denote a zero function or 1 might represent the identity matrix, for example.
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