Editing Disjoint union (section)

== Example ==

Consider the sets <math>A_0 = \{5, 6, 7\}</math> and <math>A_1 = \{5, 6\}.</math> It is possible to index the set elements according to set origin by forming the associated sets
<math>\begin{align}
A^*_0 & = \{(5, 0), (6, 0), (7, 0)\} \\
A^*_1 & = \{(5, 1), (6, 1)\}, \\
\end{align}
</math>

where the second element in each pair matches the subscript of the origin set (for example, the <math>0</math> in <math>(5, 0)</math> matches the subscript in <math>A_0,</math> etc.). The disjoint union <math>A_0 \sqcup A_1</math> can then be calculated as follows:
<math display="block">A_0 \sqcup A_1 = A^*_0 \cup A^*_1 = \{(5, 0), (6, 0), (7, 0), (5, 1), (6, 1)\}.</math>