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Re: (any documentation for) linear syntax?

  • To: mathgroup at
  • Subject: [mg107569] Re: [mg107534] (any documentation for) linear syntax?
  • From: John Fultz <jfultz at>
  • Date: Wed, 17 Feb 2010 07:03:48 -0500 (EST)
  • Reply-to: jfultz at

If you want to search for a typeset form in the Find/Replace dialog, I strongly 
recommend not doing this by hand.  Instead, use Edit->Enter Selection while you 
have an instance of the thing you're looking for selected.  Mathematica will
automatically convert it to the right form for you.

That's really all you need to know.  The rest of my response is for anyone who 
wants to understand a bit more about the details of the system, and cares to
hear any ramblings and ruminations I might have to offer about it.

The form you're talking about is not documented exhaustively, but it is 
documented.  In the help viewer, enter the following to find it...


This form is the only way in which boxes can be represented inside of strings.  
That is, by the way, where the term "linear syntax" comes from.  In a string, 
you must have a linear representation (as opposed to an expression tree) because 
strings are a linear sequence of characters.

This is all a bit unfortunate, because linear syntax can get extremely unwieldy, 
and it's particularly inside of strings where it becomes most unwieldy due to 
subtle issues with how the backslash escaping mechanism works within strings.  
While it's possible to create such forms by hand, we generally don't recommend 
it, and recommend instead using the various built-in ways of auto-converting
when necessary (the documentation points to some of these).

If it sounds like I'm not exactly thrilled about how we designed this aspect of 
the system, that's because I'm not.  There are several gotchas I haven't fleshed 
out here, and with the hindsight that we now have, we could probably have done 
this better.  Maybe we will someday.  In the mean time, when you do have to
interact with it, it's best to let the system work it out for you.  In the case 
of Find/Replace, that tends to be pretty simple using the method I described in 
my first paragraph.


John Fultz
jfultz at
User Interface Group
Wolfram Research, Inc.

On Tue, 16 Feb 2010 03:52:49 -0500 (EST), divisor wrote:
> Hello MathGroup:
> Solving a recent problem I had, Maxim mentioned that this string:
> Subscript[\[Alpha], 23]"
> can be used in the Find-Replace dialog by its evaluated equivalent
> using this string:
> \!\(\[Alpha]\_23\)
> He called this "linear syntax".
> Since I will have other expressions that I need to convert into a form
> like this, I tried to look this up in the help documentation. No luck
> when trying these pages:
> guide/Syntax
> tutorial/SpecialWaysToInputExpressions
> Can anyone tell me what this is called in the documentation or where I
> can find documentation describing it?
> Thanks in advance.
> Roger Williams
> Franklin Laboratory

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