partition

Def pg. 199

For a closed bounded interval $[a,b]$, we can say $\mathcal{P}=\{x_{i-1},x_i{\}}_{i=1}^n$ is it’s partition where $x_0=a$ and $x_n=b$. By definition, we can say $\mathcal{P}$ is the set of points that split the $[a,b]$ into many non-overlapped sub-interval.