X-VM-v5-Data: ([nil nil nil nil nil nil nil t nil]
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Date:         Fri, 20 Apr 90 08:42:52 PDT
Reply-To: LaTeX-L Mailing list <LATEX-L%DHDURZ1@unido.bitnet>
From: Leslie Lamport <lamport@SRC.DEC.COM>
Subject:      proposal
To: Rainer Schoepf <BK4@DHDURZ1.uucp>
Status: R
X-Status: 
X-Keywords:                  
X-UID: 84


One of the serious drawbacks of markup languages like TeX is that
formulas written in the source language are difficult to read.  Below
are some rambling observations leading to a possible proposal to
address this problem.

I have occasion to write a lot of logical formulas on-line.  Since I
have to read them as I write them, I write them in hand-formatted
ascii.  I have written a variant of the verbatim environment to convert
some ascii strings to symbols, so I can print the formulas in a more
readable form than they appear on my screen.  Some of the
transformations are:

       /\ = \land
       \/ = \lor
        ~ = \neg
       [] = \Box
       -> = \rightarrow
       => = \Rightarrow
       || = \|
      (+) = \oplus

In addition, :foo: is mapped to $\foo$, which allows me to do things
like

      :o: = \circ
     :oo: = \infty
    :cup: = \cup

The latter turns out to be useful because "A :cup: B" is easier to read
on the screen than "A \cup B".  I would also like to do things like
:+/-: = \pm, but haven't been willing to do the large amount of hacking
that requires.  (Today's TeX puzzle: why won't
     \expandafter\def\csname +/-\endcsname{...}
work?)

I would find it quite convenient to write formulas in LaTeX documents
in a similar way.  For example, $A /\ B => C$ is a lot nicer than
$A \land B \rightarrow C$.  Of course, while logicians might like the
translations I use (/\ = \land), physicists would probably prefer their
own notation.  Moreover, astrophysicists and nuclear physicists might
want different notations; and perhaps astrophysicists working on
stellar evolution might want different notations from astrophysicists
working on galactic dynamics.  Maybe everyone needs their own private
notation.  So here are some questions:

1.  Can one implement a set of notations that wouldn't cripple ordinary
features.  For example, it's easy to make [ an active character so [] =
\Box, but can that be done in such a way that \left[ still works?

2.  If the answer to 1 is yes, is there a reasonably small set of
notations (logic, analysis, physics, ...) that are useful enough to
be worth implementing (with style options)?

3.  Is there some way to let the user easily create his own notations?

4.  Is there anyone willing to invest the work needed to answer these
questions?

Leslie Lamport