# [Xy-pic] xy-pic question

Ross Moore ross at ics.mq.edu.au
Sat Jan 9 23:59:08 CET 2010

Hi Michael,

On 07/01/2010, at 1:11 AM, Michael Gass wrote:

> Ross,
>
> How can I get something like $A \subseteq B$ within xy-pic?
> In particular, how can I get a vertical version of the above?
> For instance, a triangle where the left and right side "arrows"
> are replaced by subset symbols.  I have looked hard in the
> documentation and cannot find how to do it.

Is this what you want ?

Set an empty arrow, then drop the character (rotated)
half-way along, as a "break".

To get the rotated character you'll need to use the
PostScript backend, which requires processing via
dvips + Ghostscript, rather than directly in pdfLaTeX.

So the Xy-pic Reference manual for the syntax to specify
rotating a character to match the current direction
(which is set by the empty arrow).

>

Alternatively, you might just put the \subseteq symbols
above ordinary arrows, as a label.
But even then you may want to rotate it.

Here is example coding:

\documentclass[11pt]{article}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage[dvips,ps,rotate,all]{xy}
\begin{document}
$$\xymatrix{ & A \ar@{}[dl]|*[vflip][@]{\subseteq} \ar@{}[dr]|*[@]{\subseteq}& \\ B\ar [rr]|*+[@]{\subseteq}& & C }$$

$$\xymatrix{ & A \ar[dl]_(.4)*+[vflip][@]{\scriptstyle\subseteq} \ar[dr]^*-[@]{\scriptstyle\subseteq}& \\ B\ar [rr]^{\subseteq}& & C }$$
\end{document}

... which produces the attached image.

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Note the need to "flip" the character before rotating,
to make it point down & left.

>
> Michael Gass

Hope this helps,

Ross

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Ross Moore                                       ross at maths.mq.edu.au
Mathematics Department                           office: E7A-419
Macquarie University                             tel: +61 (0)2 9850 8955
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