Iwasawa module
= Iwasawa module
{c}
An Iwasawa module is a <module> over an <Iwasawa algebra>. In arithmetic towers it usually comes from a norm inverse limit of units or class groups, or from a <compact Galois module> for a maximal abelian pro-$p$ extension. Specify which extension is allowed to ramify: the <p-ramified Iwasawa module> and the <unramified Iwasawa module> have different ranks.