Definition of subpartition

Question

I stumbled on the expression subpartition of a set: in my context $V$ is a set (of nodes) and "$A, B$ is a subpartition of $V$".

What does this phrase means exactly and how does it differ, if it does, from a partition?

Answer 1

A subpartition is a subset of a partition.

$A$ and $B$ are disjoint subsets of $V$ but their union may not be exhaustive.

$A\subseteq V$, $B\subseteq V$, $A\cap B=\emptyset$, $A\cup B\subseteq V$