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 Post subject: Normal subgroups.Posted: Sun, 8 Apr 2012 21:59:37 UTC
 S.O.S. Oldtimer

Joined: Sat, 21 Jan 2012 03:59:22 UTC
Posts: 182
Trying to understand normal subgroups . Book says H is a normal subgroup if, for a in H and x in G, xax^-1 is in H.

Does this mean for example say i have a groups under the operation of multiplication: G={e,1,2,1/2,3,1/3} and H is a subgroup of G, ie H={e, 2, 1/2}

then H is normal since for example 3x2x(1/3)=2 and 1x2x2=2, 2 is in H ?

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 Post subject: Re: Normal subgroups.Posted: Mon, 9 Apr 2012 00:22:58 UTC

Joined: Sat, 26 Apr 2003 22:14:40 UTC
Posts: 2064
Location: El Paso TX (USA)
Is G a group? Isn't ?

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 Post subject: Re: Normal subgroups.Posted: Mon, 9 Apr 2012 01:05:44 UTC
 S.O.S. Oldtimer

Joined: Sat, 21 Jan 2012 03:59:22 UTC
Posts: 182
yea you are right. change it to G={0,1,2,1/2} H={2,1/2}

Or give me an example

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