\begin{definition}[Definition:Greatest Common Divisor/Also known as]
The '''greatest common divisor''' is often seen abbreviated as '''GCD''', '''gcd''' or '''g.c.d.'''
Some sources write $\gcd \set {a, b}$ as $\tuple {a, b}$, but this notation can cause confusion with ordered pairs.
The notation $\map \gcd {a, b}$ is frequently seen, but the set notation, although a little more cumbersome, can be argued to be preferable.
The '''greatest common divisor''' is also known as the '''highest common factor''', or '''greatest common factor'''.
'''Highest common factor''' when it occurs, is usually abbreviated as '''HCF''', '''hcf''' or '''h.c.f.'''
It is written $\hcf \set {a, b}$ or $\map \hcf {a, b}$.
The archaic term '''greatest common measure''' can also be found, mainly in such as {{ElementsLink}}. 
Category:Definitions/Greatest Common Divisor
\end{definition}