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- Path: sparky!uunet!dtix!darwin.sura.net!spool.mu.edu!agate!agate!matt
- From: matt@physics.berkeley.edu (Matt Austern)
- Newsgroups: sci.physics
- Subject: Re: What do we know about choice of groups?
- Message-ID: <MATT.92Sep11110444@physics.berkeley.edu>
- Date: 11 Sep 92 15:04:44 GMT
- References: <1992Sep11.021551.1744@nuscc.nus.sg> <MATT.92Sep10231327@physics.berkeley.edu>
- <26236@dog.ee.lbl.gov>
- Reply-To: matt@physics.berkeley.edu
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- Organization: Lawrence Berkeley Laboratory (Theoretical Physics Group)
- Lines: 28
- NNTP-Posting-Host: physics.berkeley.edu
- In-reply-to: sichase@csa3.lbl.gov's message of 11 Sep 92 18:35:58 GMT
-
- In article <26236@dog.ee.lbl.gov> sichase@csa3.lbl.gov (SCOTT I CHASE) writes:
-
- > >leaving an infinite number, but a much smaller infinity than without
- > >that constraint. ^^^^^^^^^^^^^^^^^^^^^^^
- >
- > ??! Are you sure? They are a countably-infinite set to start with, no?
-
- I just knew somebody would call me on my choice of wording; I was
- hoping that if I used sloppy language, I could get away with not
- explaining exactly what I meant.
-
- What I meant was that a priori, if all you know is that you want a
- simple Lie group, you could choose any of the classical or exceptional
- groups, but after demanding that the group have compex representations
- (I forgot about this in my last posting!) and that anomalies cancel,
- you can eliminate everything except (if I'm remembering right) E(6),
- SU(4n+1), and SO(4n+2).
-
- It certainly is true that you start with a countably infinite set and
- you still have a countably infinite set, but if you're making a list
- of the possibilities, you'll cross out most of the exceptional groups,
- and most of the sequences of classical groups, and even some of the
- classical groups in the sequences that remain.
- --
- Matthew Austern Just keep yelling until you attract a
- (510) 644-2618 crowd, then a constituency, a movement, a
- austern@lbl.bitnet faction, an army! If you don't have any
- matt@physics.berkeley.edu solutions, become a part of the problem!
-