# Definition:Little-Omega Notation/Definition 2

## Definition

Let $f: \N \to \R, g: \N \to \R$ be two real sequences, expressed here as real-valued functions on the set of natural numbers $\N$.

Let:

$\ds \lim_{n \mathop \to \infty} {\frac {\map f n} {\map g n} } = \infty$

Then:

$\map f n \in \map \omega {\map g n}$

## Notation

The expression $\map f n \in \map \omega {\map g n}$ is read as:

$\map f n$ is little-omega of $\map g n$

While it is correct and accurate to write:

$\map f n \in \map \omega {\map g n}$

it is a common abuse of notation to write:

$\map f n = \map \omega {\map g n}$

## Also known as

Note that in the Greek alphabet, $\omega$ is the minuscule counterpart of the capital letter $\Omega$.

Hence the former is called little-omega and the latter big-omega.

Some sources, therefore, write $\omega$ notation as little-$\omega$ notation, despite the fact that $\omega$'s "little"-ness is intrinsic.

$\mathsf{Pr} \infty \mathsf{fWiki}$ may sometimes adopt this convention if clarity is improved.

## Also see

• Results about little-$\omega$ notation can be found here.