Commutative Diagrams in TeX

Unlike many other packages there is no "installation procedure" - you just copy the macros to your TeX macros directory.

The manual is provided in several formats: LaTeX source, standard DVI, 300dpi A4 PostScript and 300dpi A5 PS booklet. The "booklet" form requires a two-sided printer; if you don't have such a thing, don't bother taking the file.

Here is a prototype for emulation of Francis Borceux's macros.

If you are fetching this from any site other than theory.doc.ic.ac.uk and have not already done so, please register as a user by sending a message to <pt@doc.ic.ac.uk> with the words "commutative diagrams" in the subject line.

Here is the obsolete manual for version 2, in DVI and LaTeX form. (The only use for this is that it contains a table of the codes for LaTeX arrowheads in the various directions.)

There are also some macros for proofs and other things.

Towards Version 4

This message brings news of the development of my TeX package for drawing "commutative" diagrams, which is now widely used in the category theory and theoretical computer science communities. It is being sent directly to all of the users I know of (who have requested it by electronic mail or FTP from me, or asked questions about it), but as I know the package has been passed on, I would be grateful if you would copy this message to anyone to whom you have given the package itself.

The package was originally advertised on the "types" and "categories" electronic mailing lists in July 1990. In the following eighteen months some fixing of bugs took place, but there was little substantial change.

Since April 1992, I have re-written most of the code, largely with a view to improving the geometrical layout of the diagrams. Before completing this work and calling it version 4, I would like some feedback from users.

One of the areas which I have neglected in the past (largely because TeX makes it so difficult) is diagonal arrows. The code for drawing these using LaTeX line segments has been re-written: now the closest available slope is chosen automatically and the commands have names similar to the horizontals and verticals.

However to do a better job of diagonals (and in future to support curved lines) some extension to TeX is needed. Being extensions they are necessarily not standard. Three possibilities are:

1. additional fonts (as, for example, used by Spivak's Lamstex). However my experience of design-size fonts and linear logic symbols suggests that for users without expert knowledge or control of their local TeX systems this is more trouble than it's worth.
2. PostScript is, I believe, now almost universally used as the language in which TeX documents are sent to a printer. PS commands can be embedded in DVI files and incorporated in the PS translation without extra system or user files or any user intervention. This is to some extent dependent on which DVI->PS translator is used. In the new version this is exploited in an option to implement diagonals by rotating horizontals, which works with Tomas Rokicki's "dvips".
3. TPIC is a graphics extension of TeX which uses a simpler set of embedded commands. These can be used to draw diagonal lines and curves but not to perform rotations; they are, however, understood by Vojta's "xdvi" as well. Another option in the new version uses these to draw diagonal lines.

Arrow commands are now declared in a much simpler way. The declaration

	\newarrow{CrossedInto}{hook}-+->

So much for selling you the new version. The reason for mailing you and asking for comments before completing what I intend to do for version 4 is that I want to get feedback on the following questions:

1. Can you use FTP (file transfer protocol)? This is the easiest method of distribution for me and for you, and there is now a huge volume of public domain software available by this method. My archive is called

   	theory.doc.ic.ac.uk	(146.169.2.37)
   

   and the diagrams package is in the directory /tex/contrib/Taylor/tex. Please try to fetch the new version and manual by this method.
2. If you can't use FTP, and your electronic mail passes via non-ASCII machines (particularly BITNET), what characters tend to get corrupted? The new version uses a restricted character set to avoid this problem.
3. Do you have available for printing final copy a printer which understands Adobe PostScript, for example an Apple or Sun laserwriter? Who is the author of the DVI->PS translation program you use? Please fetch the new version, try the PostScript option and tell me if you have any difficulty printing. (You may have to change the \verbatim@ps@special macro if you don't use Rokicki's dvips: if so, please send me details.) You can preview with a PS previewer such as PageView under OpenWindows or GhostView/GhostScript under Xwindows.
4. Do your DVI translators and previewers understand TPIC \specials (as used in eepic.sty)? Please try the TPIC option. I would like to know whether it is worth putting effort into PostScript, TPIC or some other method.
5. Have you defined your own arrow commands using \HorizontalMap, \VerticalMap or \DiagonalMap? Please use "grep alMap *.tex *.sty" or some similar command to find out, and tell me if you have used any components other than those in the source of version~3. It is in your interests to do this, because \newarrow defines arrow commands in a different way.
6. Please tell me if you have any difficulty adapting to the new version, or any general comments about doing so which might be of benefit to other users.
7. Other comments: have you used other packages for drawing diagrams? Do you have applications for my package other than the categorical diagrams for which it was designed? What do you see as the major limitations of the package? What persuaded you to use it, or not to use it?

• 2 was circulated to some people in September 1989
• 3.16 was advertised on types & categories in July 1990 and emailed to those who asked for it.
• 3.18 was the final bug-fix before the re-write began in April 1992.
• 3.20 introduced error-recovery, and \newarrow for horizontals & verticals
• 3.22 completely rewrote the reformatting program for h & v and corrected numerous alignment errors; introduced options in square brackets
• 3.23 fixed a catastrophic error in nested diagrams
• 3.24 (current) extended \newarrow to diagonals, added trigonometry code, rewrote code for drawing LaTeX diagonals, introduced PostScript and TPIC diagonals, consistent choice of arrowheads.

Paul Taylor, pt@doc.ic.ac.uk, +44 171 59 48263, 7 September 1992

Department of Computing, Imperial College of Science, Technology & Medicine, 180 Queen's Gate, South Kensington, London SW7 2BZ, UK.