[Xy-pic] Re: Xy-pic digest, Vol 1 #9 - 1 msg

Robert A.G. Seely rags@math.mcgill.ca
Mon, 30 Jul 2001 08:16:52 -0400 (EDT)

On Mon, 30 Jul 2001 xy-pic-request@tug.org wrote:

> I'm hoping someone can help by telling me how to draw the little
> `right-angle' device often used to show that a certain commuting square is
> a pullback/pushout using xypic.

This may be somewhat off-topic as a reply, but Michael Barr has
produced a "front end" to certain xypic features of frequent use in
producing categorical diagrams, including the pullback square you ask
of.  It is perfectly possible to mix his macros with "plain" xypic, so
this *adds* to xypic's functionality, not *substitutes*.

Try them out to see if you fancy them (at least download the macro
package and tex the manual to see what it looks like - the manual
includes the pullback); the url is


(Warning!: Michael did produce an earlier diagram package, which does
not use xypic in any fashion - be sure to get the latest version, if
you download his macros from any other location.)

-= rags =-

R.A.G. Seely