CoCoA » CoCoA-5

Since CoCoA-5 allows indets with long names, I wanted to revise LaTeX.cpkg5 so that the product x*y looks different from the indet xy. I did this by inserting a little space between indets in a power-product.

There may be other ways of distinguishing the two cases. For instance an indet called alpha should probably be translated into LaTeX \alpha; but I am not sure how to do this in a "scalable" way.

Currently only exponents greater than 9 are printed inside curly brackets; presumably it is done this way because that is what a person would do. Why not put all exponents inside curly brackets? Can we ever have negative exponents? Perhaps not yet; maybe never!

I think that using \ideal{...} for ideals is better than just putting the gens inside round brackets, because the user can then define \ideal to do "the right thing". It also adds a "semantic hint" to the generated LaTeX.

Made simpler in easy, common cases: when all the indets in the ring are single letters, then the indets in a power-product
are separated by " " (i.e. a space). Otherwise they are separated by "\!\:".

John Abbott wrote:

Perhaps the criterion in comment 3 should consider only those indets which actually appear in the PP? (or is that too un-KISS-like?)

sounds un-KISS.
Another proposal could be that indets with more than one letter are printed with "\".
Indeed, if I'm using "alpha" in cocoa, I probably think of "\alpha" in TeX.

I am a little unhappy about \!\: which does look rather ugly.
Maybe it is OK if (at least) one of the indets does have a long name?
I'd like to re-propose my suggestion in comment 9: use spacing only if at least one indet is long.

John Abbott wrote:

I like the suggestion of putting a backslash in front of all long indet names:

• if the indet name is a greek letter then it will do just what is wanted
• if the indet name is not a greek letter then the user must anyway intervene manually to say how to print it
  (and a good approach is to define an appropriate LaTeX macro)

this is still my preferred choice.
Moreover, I'd leave a space " " (not "\;") between indet names if there is at least one with a not-single-letter name. This is just to make the LaTeX source more readable/robust (e.g. "$\alpha x y$")

I think I now agree with Anna's comment 15.
If there are long indet names then the user will almost surely have to refine the LaTeX output manually,
so we may as well make the LaTeX output as easy-to-read as possible: in other words we just put a space
between indet names (but a long is preceded by a backslash).

Example of my latest "hack":

/**/ use QQ[x,alpha,y];
/**/ LaTeX(x*alpha*y);
x \alpha y

NOTE: we currently separate indexes by \, -- is this what we want?