[Xy-pic] Spacing problems with triangles

Jürgen Koslowski koslowj at iti.cs.tu-bs.de
Tue Mar 30 15:03:04 CEST 2004

Hello,

I encountered an annoying spacing problem when displaying triangular
diagrams.  The top corner is much too close to the preceeding text, in
case of a short line even protrudes into that line.  So far I have
used invisible entries to get around this problem, is there a better
way?  Enclosing the diagram into \vcenter{...} does not help.

Here is an example:

\documentclass[11pt]{article}
\usepackage[arrow,2cell,line,dvips,ps]{xy}

%\CompileMatrices
\UseAllTwocells

\setlength{\textwidth}{16 cm}
\begin{document}

If for a 2-cell
$\xy ;<50 pt,0 pt>: (0.0,0) *+{A}="A", (0.5,\halfrootthree) *+{B}="B", (1.0,0) *+{C}="C", "A";"C",{\twocell<\omit>{<-3>{\ \phi}}}, \ar_{t}"A";"C" \ar^{r}"A";"B" \ar^{s}"B";"C" \endxy$
pasting at $s$ is bijective, we call $\langle s,\phi\rangle$ a right
extension of $t$ along $r$.

Even if the line preceeding the diagram is longer, the placement
is better but we still have a problem.  There seems to be too little
space above the diagram:
$\xy ;<50 pt,0 pt>: (0.0,0) *+{A}="A", (0.5,\halfrootthree) *+{B}="B", (1.0,0) *+{C}="C", "A";"C",{\twocell<\omit>{<-3>{\ \phi}}}, \ar_{t}"A";"C" \ar^{r}"A";"B" \ar^{s}"B";"C" \endxy$
I don't want to put in extra invisible elements to get the spacing right.

\end{document}

-- Juergen

--
Juergen Koslowski               If I don't see you no more on this world
ITI, TU Braunschweig               I'll meet you on the next one
koslowj at iti.cs.tu-bs.de               and don't be late!
http://www.iti.cs.tu-bs.de/~koslowj      Jimi Hendrix (Voodoo Child, SR)