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From: ribet@maalox.berkeley.edu (Kenneth A. Ribet)
Newsgroups: comp.text
Subject: Double subscripts and \mathaccent's in TeX
Message-ID: <1989Oct9.214708.8873@agate.berkeley.edu>
Date: 9 Oct 89 21:47:08 GMT
Sender: usenet@agate.berkeley.edu (USENET Administrator;;;;ZU44)
Reply-To: ribet@maalox.UUCP (Kenneth A. Ribet)
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Organization: Math Dept., UC Berkeley
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Hello, everyone.  I'm posting this question to find out whether
the peculiarity of TeX which I ran into this morning is a well known
phenomenon.

Consider the expressions ${A_B}_C$ and ${\tilde A}_B$.  They pose
no problems for TeX.  However, TeX refuses to process the expression
    ${{\tilde A}_B}_C$,
claiming that there is a ``double subscript.''  The only workaround
for this that I know is to embed the $\tilde A$ in a \hbox.

Presumably, this behavior is explained by the rules in Appendix G
of the TeXbook; even so, I find it a bit illogical.

Am I doing something wrong?  Is my difficulty familiar to everybody?

-ken ribet, UC Berkeley Math Department

...ucbvax!math!ribet        ribet@math.berkeley.edu