オーギュスタン＝ルイ・コーシー
In his "Disquisitiones Arithmeticae" in 1801, Carl Friedrich Gauss proved Lagrange's theorem for the special case of formula_21, the multiplicative group of nonzero integers modulo , where is a prime. In 1844, Augustin-Louis Cauchy proved Lagrange's theorem for the symmetric group .