Definition:Division Algebra/Definition 1
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Definition
Let $\struct {A_F, \oplus}$ be an algebra over field $F$ such that $A_F$ does not consist solely of the zero vector $\mathbf 0_A$ of $A_F$.
$\struct {A_F, \oplus}$ is a division algebra if and only if:
- $\forall a, b \in A_F, b \ne \mathbf 0_A: \exists_1 x \in A_F, y \in A_F: a = b \oplus x, a = y \oplus b$
That is, for every pair of elements $a, b$ of $A_F$ where $b$ is non-zero, there exists:
- a unique element $x$ such that $a = b \oplus x$
- a unique element $y$ such that $a = y \oplus b$
Also see
- Division Algebra has No Zero Divisors, in which the two definitions are shown to be equivalent.
- Results about division algebras can be found here.
Sources
- 1992: George F. Simmons: Calculus Gems ... (previous) ... (next): Chapter $\text {B}.26$: Extensions of the Complex Number System. Algebras, Quaternions, and Lagrange's Four Squares Theorem
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): division algebra
- 2002: John C. Baez: The Octonions : 1.1 Preliminaries
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): algebra: 2.
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): division algebra