A new version of LaTeX is being produced and I have agreed to participate in a subproject to decide on the best syntax for commutative diagrams. I am not at all sure that I know what the best syntax is. Mine is good for some purposes; not so good for others. There are a set of macros by Kris Rose (not specifically for LaTeX, but they will work with it) that really produce good results, but not if you put long labels on diagrams. They can be modified to work better in that case, but then get much more complicated. Then there are Paul Taylor's macros, which have advantages, but are certainly inferior to Rose's (the latter use their own fonts, which is a large reason for their superiority). Anyway, I welcome all suggestions. Michael Barr ==============================================================================
Michael Barr writes:
A new version of LaTeX is being produced and I have agreed to participate in a subproject to decide on the best syntax for commutative diagrams.
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(the latter [Rose's macros] use their own fonts, which is a large reason for their superiority).
Without having any knowledge of Rose's package, I would much prefer to have complete flexibility in the choice of labels. Two reasons for this are: (i) labels in the diagrams should agree with those in the text, and; (ii) fonts change more rapidly than diagram styles. One further point comes to mind. If other fonts can't be imported, then perhaps other macros can't be used either. For example, one might use arrays to label linear transformations. I suggest as a design criterion that Any box should be admissible as a label. Barry Jay ==============================================================================
Mike Barr has pointed out that some La/TeX packages for commutative diagrams or general graphics use specially provided fonts. My own experience with *any* divergence from the fonts provided in bog-standard TeX distribution causes more trouble than it's worth: witness the design size (Sauter) fonts in particular. (Incidenatlly, these are now no longer used by default in our local LaTeX implementation, and so should not be needed when fetching dvi files from our archive at theory.doc.ic.ac.uk). *Not* using extra fonts is listed as one of the design criteria of my diagrams package. Nevertheless, unlike any of the others I've seen (including Mike's) it does provide facilities for you to define arrow heads in terms of whatever fonts you like. If there is demand (which I haven't heard) I am willing to include macros for using other fonts within my package. However fonts are a red herring: where Mike came in was on the *syntax* of macros for expressing diagrams. With respect, but since he has thrown down this gauntlet, I find it amazing that the author of a package with as bizzare a syntax as his, who has submitted to this list a LaTeX document which directly conflicts with the recent developments in LaTeX, should be involved in proposing an authoritative syntax. A great deal of thought and work has gone into the design of the language in my package. Indeed there are many features I could have added but haven't because I haven't thought of the right language for expressing them. ============= Last week I was reading a recent paper which used my diagrams (I'm not going to say whose). The version used must have been about five years old and really made me cringe, because of the bugs in it which were fixed long ago. If you have a version dated before July 1990 or which is undated *PLEASE* throw it away and use a new one. The diagrams look so much better nowadays! If there are any problems, I shall be happy to help. Paul ==============================================================================
I should clarify, for the benefit of those who think I meant that xypic (the package in question) uses its own fonts for the arrow sources or labels, I should clarify that it uses the ordinary TeX fonts except for the arrows. These are built from line segments at 256 different slopes, giving angular resolution of 256/180 = .7 deg and 512 half arrowheads giving arrowheads at that many angles. The arrowheads are extremely graceful, more elegant than those in ordinary Tex and massively more elegant than those of latex. Other than that, it uses whatever your symbol font is. For example, you could substitute the concrete math fonts, if you wanted. I have gotten several replies, the most interesting from David Benson who feels that xypic is probably the best, but that there shouldn't be just one, but a choice. He feels that a package that makes it hard to draw a complicated diagram that *also* has complicated arrow labels should be encouraged, so that people tempted to use such a horror be discouraged. Perhaps I have stated it a bit more strongly than he would, but that is the thrust of his remarks. Michael ==============================================================================
I didn't reply to the diagram syntax question because I couldn't come up with a phrasing of my druthers that adequately hid how much larger my eyes were than my mouth. But J"urgen just now expressed what I really wanted beautifully, so let me add my vote to his request. -Vaughan Pratt ==============================================================================
participants (4)
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barr＠triples.Math.McGill.CA -
cbj＠dcs.ed.ac.uk -
Paul Taylor -
pratt＠cs.stanford.edu