In L.Washington Introduction to Cyclotomic fields, Chap 8, p 146 we read:
Finding nontrivial examples appears to be difficult since $h_n^+=1$ for small $n$ and for large $n$ the calculations required to determine $E^+$ or the class group are extremely lengthy. The next question is whether or not the $p$-part of $E^+/C^+$ is isomorphic to the $p$-Sylow subgroup of the class group of $\Bbb Q(\zeta_{p^m})$.
I guess in this context, $E^+$ and $C^+$ denote respectively the full unit group and the cyclotomic units group of the maximal real part of $\Bbb Q(\zeta_{p^m})$ and $C^+$.
But what is the $p$-part of $E^+/C^+$? I couldn't find a definition in the book or elsewhere. Is it $p$-subgroup of $E^+/C^+$?
Thank you.
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