Index of a subgroup
= Index of a subgroup
{wiki=Index_of_a_subgroup}
In group theory, the index of a subgroup is a concept that helps to measure the "size" of the subgroup in relation to the larger group it belongs to. Specifically, if \\( G \\) is a group and \\( H \\) is a subgroup of \\( G \\), the index of \\( H \\) in \\( G \\), denoted as \\( \[G : H\] \\), is defined as the number of distinct left cosets of \\( H \\) in \\( G \\).