A [[subset]] ''H'' of a [[group]] (''G'',<math>\cdot</math>) is called a '''subgroup''', if (''H'',<math>\cdot</math>) is itself a group. | A [[subset]] ''H'' of a [[group]] (''G'',<math>\cdot</math>) is called a '''subgroup''', if (''H'',<math>\cdot</math>) is itself a group. |