Satz von Lagrange - Perle der Gruppentheorie

Lagrange's theorem is an important theorem in group theory and states a necessary, but not sufficient, condition for the existence of a corresponding subgroup of a given finite group of a given order. The theorem states that the order of such a subgroup divides the order of the entire group. This video proves Lagrange's theorem. Related videos: Mappings, injective, surjective, bijective - Appetizers from set theory:    • Abbildungen, injektiv, surjektiv, bijektiv...   Group theory playlist:    • Gruppentheorie   The video on the dihedral group D4 and its subgroups mentioned in the article can also be found in the group theory playlist.