\overgroup{AB}The command \overgroup{AB} is used to place a horizontal line (or overbar) over the group of characters or symbols 'AB'. This is often used in mathematical notation to denote a specific group or set, or to indicate a particular operation or relation involving the grouped elements.
Indicating a grouped operation or relation involving AB and CD.
\overgroup{AB} + CD = EFDenoting that the group XY is a subset of Z.
\overgroup{XY} \subseteq ZUnion of two groups PQ and RS resulting in T.
\overgroup{PQ} \cup \overgroup{RS} = T