[Xy-pic] Really strange behavior

[Ross Moore]

Hi Michael,

On 28/07/2014, at 8:05 AM, Michael Barr wrote:

> Can anyone explain this behavior?  Compile this:
> 
> \documentclass{article}
> \pdfoutput1
> \usepackage[all]{xy}
> \begin{document}
> $$ \xy
>   \POS(0,0)*+!!<0ex,0ex>{A}\ar^{f}(20,20)*+!!<0ex,0ex>{B}{}
>   \POS(0,0)*+!!<0ex,0ex>{A}\ar^{f}(20,20)*+!!<0ex,0ex>{B}
> \endxy $$
> 
> This doesn't happen if you remove the pair of braces at the end of the
> first line.

Those braces kill the Xy-pic parser, and result in an extra space
character inside the internal \hbox that is being built.

Simply add a % character; viz.

  \POS(0,0)*+!!<0ex,0ex>{A}\ar^{f}(20,20)*+!!<0ex,0ex>{B}{}%
  \POS(0,0)*+!!<0ex,0ex>{A}\ar^{f}(20,20)*+!!<0ex,0ex>{B}

Now the 2 arrows and objects overlay each other.
Are you trying to simulate bold-face ?


> \end{document}



Hope this helps,

	Ross

------------------------------------------------------------------------
Ross Moore                                       ross.moore at mq.edu.au 
Mathematics Department                           office: E7A-206      
Macquarie University                             tel: +61 (0)2 9850 8955
Sydney, Australia  2109                          fax: +61 (0)2 9850 8114
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