Re: Centralizers, Normalizers and the Center



In article <24084316.1120699807491.JavaMail.jakarta@xxxxxxxxxxxxxxxxxxxxxx>,
Lawrence House <lawrence.house@xxxxxxxxxxx> wrote:

>I'm confused by the notation. Is C_H(G). Is it (1) the set of all
elements in H which commute with all of G? or (2) Z(H) the
centralizer of H?

Ehr, C_H(G) is usually the set of all elements in H that commute with
each (all) elements of G. Z(H) is normally the CENTER of H, that is,
the elements of H that commute with every element in H.

Since you did not quote the original, however, it seems hard to say
what the original meaning was meant to be.

> If (1) it is the intersection of Z(G) with H and
>therefore a subgroup of G. If (2) it is a subgroup of H and therefore
>again a subgroup of G.

>Also what is meant by N_H(G)? Might this be the set of all elements
of G that commute with all elements of H?

N_H(G) is usually the normalizer in H of G: all elements h in H such
that hGh^{-1}=G.


--
======================================================================
"It's not denial. I'm just very selective about
what I accept as reality."
--- Calvin ("Calvin and Hobbes")
======================================================================

Arturo Magidin
magidin@xxxxxxxxxxxxxxxxx

.



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