Universal Music Group | Warner Music Group | Coxeter group | Volkswagen Group | Group of 77 | RTL Group | girl group | BT Group | ABB Group | Group One | Virgin Group | Thales Group | ING Group | group | Rio Tinto Group | Bloomsbury Group | Penguin Group | Carlsberg Group | Borders Group | Arup Group Limited | Gym Class Heroes | Benetton Group | Stagecoach Group | LMFAO (group) | class action | Anschutz Entertainment Group | Tata Group | Rootes Group | class | Westfield Group |
In algebraic number theory, a reflection theorem or Spiegelungssatz (German for reflection theorem – see Spiegel and Satz) is one of a collection of theorems linking the sizes of different ideal class groups (or ray class groups), or the sizes of different isotypic components of a class group.