Subscripting (was: Base change notation)

[Marc LeBrun]

 >=franktaw at netscape.net

 > the usual convention with the underscore is that only the minimum 
is considered to be subscripted

Seems reasonable.  So for example 11_2 = 3 doesn't need any 
subscripts.  I'd supposed neither would 11_2->4, because the parsing 
(11_2)->4 would be meaningless, but in more complex cases it might be 
ambiguous, so we'll scope underscore so it "binds tightly".


 > As for parens vs. braces, I think you can use either...Since we're 
just presenting formulas in the OEIS...

But the OEIS is *not* just for presentation to humans, it's exposed 
to programs.  Having alternative synonyms tends to interfere with 
that.  Therefore the best practice to hew to some canonical pattern 
whenever possible.


 > (This applies to superscripts with ^, too.)

Ditto.  Hm, so by analogy we can write 11_-1 = 1?


Mumble...now I'm remembering a reason why I avoided subscripts for 
rebasing and instead again found "indexing" attractive:  In the usual 
usage of subscripts for bases the "main" term is treated as a 
*string*, while the subscript is parsed in *decimal*.

I think it's very important, so as not to reintroduce all that 
confusion, to find a way to get strings out of the picture 
completely, so all arguments can be interpreted uniformly as ordinary 
numbers and expressions.

For example, what's e_pi, if e_16 is fourteen?

And if you try to compose "subscripting" (besides getting squintier, 
as with exponents), it gets considerably more confusing.  It's not 
clear what's a string, where the implied _10s go, etc.

So maybe bringing subscripting ideas into this isn't such a good idea 
after all?

(I'll note that subscripting versus indexing is orthogonal to the 
question of argument order--connecting the "from" and "to" bases by 
an arrow certainly has its charms).


On a different note: no matter which of these notational proposals we 
adopt, the OEIS convention of ignoring punctuation makes it hard to 
find, much less change/maintain entries involving purely symbolic 
notations.  Maybe it would be better to introduce an operator with an 
alphanumeric name, such as "rebase"?