# Definition:Subdivision (Real Analysis)/Finite

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## Definition

Let $\left[{a \,.\,.\, b}\right]$ be a closed interval of the set $\R$ of real numbers.

Let $x_0, x_1, x_2, \ldots, x_{n - 1}, x_n$ be points of $\R$ such that:

- $a = x_0 < x_1 < x_2 < \cdots < x_{n - 1} < x_n = b$

Then $\left\{{x_0, x_1, x_2, \ldots, x_{n - 1}, x_n}\right\}$ form a **finite subdivision of $\left[{a \,.\,.\, b}\right]$**.

### Normal Subdivision

$P$ is a **normal subdivision of $\left[{a \,.\,.\, b}\right]$** if and only if:

- the length of every interval of the form $\left[{x_i \,.\,.\, x_{i + 1} }\right]$ is the same as every other.

That is, if and only if:

- $\exists c \in \R_{> 0}: \forall i \in \N_{< n}: x_{i + 1} - x_i = c$

## Also known as

Some sources use the term **partition** for this, but the latter term has an alternative and more general definition so it is probably better not to use it.

Some sources do not define the concept of infinite subdivision, and so simply refer to a **finite subdivision** as a **subdivision**.

## Sources

- 1977: K.G. Binmore:
*Mathematical Analysis: A Straightforward Approach*... (previous) ... (next): $\S 13.2$