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<P ALIGN=RIGHT><FONT SIZE=1>Xy-pic User's Guide</FONT> <A HREF="18pt.html"><IMG SRC="./quest.gif" ALIGN=TOP HEIGHT=27 WIDTH=21 BORDER=0 ALT="?"></A><A NAME="basicsbreaks" NAME="tex2html152" HREF="node7.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="previous" SRC="./previous.gif"></A><A NAME="tex2html156" HREF="node7.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="previous" SRC="./previoussection.gif"></A><A NAME="tex2html158" HREF="node3.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="up" SRC="./up.gif"></A><A NAME="tex2html154" HREF="node9.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="next" SRC="./nextsection.gif"></A><A NAME="tex2html160" HREF="node9.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="next" SRC="./next.gif"></A></P><H2><A NAME="SECTION00035000000000000000">1.5 Breaks</A></H2> It is also possible to "break" an arrow with a label using the
<code>|</code> character:
<code>$\xymatrix@1{A\ar[r]</code><code>|</code><code>f&B}$</code> will set <IMG WIDTH=82 HEIGHT=16 ALIGN=BOTTOM ALT="tex2html_wrap2500" SRC="img10.gif">.
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If you just want an empty break you should use the special
<code>\hole</code> break:
the arrow <IMG WIDTH=82 HEIGHT=15 ALIGN=BOTTOM ALT="tex2html_wrap2502" SRC="img11.gif"> was typeset by including <code>$\xymatrix@1{ A\ar[r]</code><code>|</code><code>\hole & B }$</code> in the
text.
<P>
A different use of breaks is to place a label somewhere in a diagram
outside the normal matrix mesh: this is
accomplished by "breaking" an invisible arrow obtained using
the <code>@{}</code> arrow style: the square
<P><CENTER><BR><IMG WIDTH=195 HEIGHT=89 ALIGN=BOTTOM ALT="displaymath199" SRC="img12.gif"><BR></CENTER><P>
was typeset by
<BLOCKQUOTE><PRE>\xymatrix{\ar @{} [dr] |{=}
A \ar[d] \ar[r] & B \ar[d] \\
B \ar[r] & C }</PRE></BLOCKQUOTE>
There is more on breaks in section <A HREF="node18.html#arrowspass">2.7</A>.
<P>
<A NAME="Exercise4"> </A><H4><A NAME="SECTION00035010000000000000">Exercise 4.</A></H4> Typeset the first axiom of category theory as the display
<P><CENTER><BR><IMG WIDTH=202 HEIGHT=107 ALIGN=BOTTOM ALT="displaymath208" SRC="img13.gif"><BR></CENTER><P>
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<A HREF="node33.html#Answer4">Answer.</A>
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<P> <P ALIGN=RIGHT><FONT SIZE=1>Xy-pic User's Guide</FONT> <A HREF="18pt.html"><IMG SRC="./quest.gif" ALIGN=TOP HEIGHT=27 WIDTH=21 BORDER=0 ALT="?"></A><A NAME="tex2html152" HREF="node7.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="previous" SRC="./previous.gif"></A><A NAME="tex2html156" HREF="node7.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="previous" SRC="./previoussection.gif"></A><A NAME="tex2html158" HREF="node3.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="up" SRC="./up.gif"></A><A NAME="tex2html154" HREF="node9.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="next" SRC="./nextsection.gif"></A><A NAME="tex2html160" HREF="node9.html"><IMG WIDTH=27 HEIGHT=27 BORDER=0 ALIGN=ABSMIDDLE ALT="next" SRC="./next.gif"></A><P><ADDRESS>
<BR><HR>
<a href="COPYING/index.html">�/a> <a href="http://www.brics.dk/~krisrose/">Kristoffer H. Rose</a>
<<a href="mailto:krisrose@brics.dk">krisrose@brics.dk</a>>
January 6, 1997
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