Bézout's Identity/Proof 6
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Theorem
Let $a, b \in \Z$ such that $a$ and $b$ are not both zero.
Let $\gcd \set {a, b}$ be the greatest common divisor of $a$ and $b$.
Then:
- $\exists x, y \in \Z: a x + b y = \gcd \set {a, b}$
That is, $\gcd \set {a, b}$ is an integer combination (or linear combination) of $a$ and $b$.
Furthermore, $\gcd \set {a, b}$ is the smallest positive integer combination of $a$ and $b$.
Proof
We have that Integers are Euclidean Domain, where the Euclidean valuation $\nu$ is defined as:
- $\map \nu x = \size x$
The result follows from Bézout's Identity on Euclidean Domain.
$\blacksquare$
Source of Name
This entry was named for Étienne Bézout.