> The number of possible forms makes the size of the expression sent to
> TeX grow exponentially.
> For each letter in the above, say b,
> let b=r^s, where r and s are expressions.
>
> Allow TeX to chose
> s
> r
>
> or expt(r,s).
>
> a combinatorial explosion...
This would be silly and I didn't suggest it. At least I didn't mean to. I
would think (as Jay pointed out), that there is only a limited number of
choices available, due to context issues. (inlined or displayed eg)
In the example above: I think it would be rather silly to have printed
text like
expt(r,s) expt(x,y) ··· expt(u,v)
---------------------------------
expt(e,f) ···
except in cases where you would like to do it by hand anyway. And the
point is: while TeX alows you to do that easily, it is nearly impossible
with postscript.
Martin