| − | 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 (mathematics)|group]] (''G'',<math>\cdot</math>) is called a '''subgroup''', if (''H'',<math>\cdot</math>) is itself a group. |