Complex sentence: The integer "t" is the index of a subgroup containing "N", known as the inertial subgroup of μ, which is\\, often denoted by I_G (\\ mu).
Split into simpler sentences: The integer "t" is the index of a subgroup of "G", containing "N", known as the inertial subgroup of μ. This is\\ and is often denoted by I_G (\\ mu).