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<H2><A NAME="SECTION004120000000000000000"></A>
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2.1.2 Boolean Operations 
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<P>
These are the Boolean operations, ordered by ascending priority:
<a name="l2h-18"></a>

<P>
<table border align=center>
  <thead>
    <tr bgcolor="#99CCFF">
      <th><b>Operation</b></th>
      <th align=left><b>Result</b></th>
      <th><b>Notes</b></th>
    </thead>
  <tbody valign=baseline>
    <tr><td align=center valign=baseline><code><var>x</var> or <var>y</var></code></td>
        <td>if <var>x</var> is false, then <var>y</var>, else <var>x</var></td>
        <td align=center>(1)&nbsp;</td>
    <tr><td align=center valign=baseline><code><var>x</var> and <var>y</var></code></td>
        <td>if <var>x</var> is false, then <var>x</var>, else <var>y</var></td>
        <td align=center>(1)&nbsp;</td>
  
    <tr><td align=center valign=baseline><code>not <var>x</var></code></td>
        <td>if <var>x</var> is false, then <tt>1</tt>, else <tt>0</tt></td>
        <td align=center>(2)&nbsp;</td></tbody>
</table>
<a name="l2h-19"></a>
<a name="l2h-20"></a>
<a name="l2h-21"></a>

<P>
Notes:

<P>
<DL>
<DD><P>
<DT><STRONG>(1)</STRONG>
<DD>These only evaluate their second argument if needed for their outcome.

<P>
<DT><STRONG>(2)</STRONG>
<DD>"<tt class=samp>not</tt>" has a lower priority than non-Boolean operators, so e.g.
<tt>not a == b</tt> is interpreted as <tt>not(a == b)</tt>, and
<tt>a == not b</tt> is a syntax error.

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</DL>

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