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<TITLE> Christian Urban </TITLE>
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<B>Links</B><BR>
<A HREF="http://www4.in.tum.de/~urbanc/index.html">Home</A><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/cutapplet.html">Applet Home</A><BR><BR><p>
<B>Java Versions</B><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/CL.html">CL</A><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/LJT.html">LJT</A><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/ND.html">ND</A><BR><BR>
<B>Plugin Versions</B><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/CL-plugin.html">CL</A><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/LJT-plugin.html">LJT</A><BR>
<A HREF="http://www4.in.tum.de/~urbanc/Cut/ND-plugin.html">ND</A><BR>
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<BR>
<A HREF="http://isabelle.in.tum.de/nominal/">
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<A NAME="Home"></A>
<H2>Normalisation in intuitionistic natural deduction</H2>
This applet implements the bog-standard version of intuitionistic
natural deduction. If you are familiar with any textbook on proof
theory (e.g. this <A HREF="http://www.amazon.co.uk/exec/obidos/ASIN/0521572231/ref=ed_ra_of_dp/026-0727529-0066055">one</A>), then most things will look very familiar to you.
Note that natural deduction is here implemented in `sequent style'.
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<B>How to use it?</B>
If your browser is working correctly, then you will see a window
with two examples (more added if I have time or you suggest one).
When you press on one of the buttons, a new window will pop up. What
follows is a brief explanation of all the features available in this window.
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<B>Buttons and Keys</B>
<UL>
<LI> The buttons
<IMG SRC="http://www4.in.tum.de/~urbanc/Cut/x.jpg">
`fire' beta-redexes (nothing surprising here).
<LI> If you use the <B>left mouse button</B> for pressing on those buttons,
then the new proof will appear inside the window. Whereas if you use
the <B>right mouse button</B>, a new window will pop up and
the new proof will be displayed in this window. Use the right mouse
button if you want to compare a proof and its reduct.
<LI> The keys <B>Page-up</B> and <B>Page-down</B> zoom in or out of a proof
respectively.
</UL>
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<B>Menu Functions</B>
<UL>
<LI> <B>Zoom in</B> and <B>Zoom out</B> work like Page-up and Page-down,
respectively.
<LI> <B>Unicode</B> If this radiobutton is switched on, logic symbols
are displayed in unicode, otherwise in ascii. (This is for the
poor guys who have a browser and/or operating system which cannot handle
unicode.)
<LI> <B>Labels</B> As mentioned earlier the sequents are composed of
two sets of labelled
formulae, not multisets of formulae as in the standard formulation
of sequent calculus. Enabling this radiobutton causes that labels are
drawn. Use this when you are unsure where implicit contractions are.
<LI> <B>Compact printing</B> Usually formulae are weakened only in axiom.
If this radiobutton is switched on (default), then, in order to save space,
formulae are weakened as soon as possible.
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<center>
<applet archive=MyApplet.zip code="MyApplet.class" width=1 height=1>
<param name="calculi" value="C">
<p><blink><FONT COLOR="#800000">
Applet should appear in a new window, but you don't have Java enabled in your browser.
</FONT></blink><p>
</applet>
</center>
<P><!-- Created: Tue Jul 3 21:01:42 BST 2001 -->
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Last modified: Sat Mar 3 05:16:48 CET 2007
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