[WWcvs] webwork-modperl: Update help file to match some recent changes in

[jj v. a. <we...@ma...>]

Log Message:
-----------
Update help file to match some recent changes in checking of answers which
are intervals.

Modified Files:
--------------
    webwork-modperl/htdocs/helpFiles:
        IntervalNotation.html

Revision Data
-------------
Index: IntervalNotation.html
===================================================================
RCS file: /webwork/cvs/system/webwork-modperl/htdocs/helpFiles/IntervalNotation.html,v
retrieving revision 1.3
retrieving revision 1.4
diff -Lhtdocs/helpFiles/IntervalNotation.html -Lhtdocs/helpFiles/IntervalNotation.html -u -r1.3 -r1.4
--- htdocs/helpFiles/IntervalNotation.html
+++ htdocs/helpFiles/IntervalNotation.html
@@ -33,6 +33,12 @@
 <br>
 <br>
 
+<li> If the answer is the empty set, you can specify that by using
+     braces with nothing inside: <code> { } </code>
+
+<br>
+<br>
+
 <li> You can use <code>R</code> as a shorthand for all real numbers.
   So, it is equivalent to entering <code>(-Inf, Inf)</code>.
 
@@ -48,7 +54,8 @@
 <br>
 
 
-<li> WeBWorK will not interpret <tt>[2,4]U[3,5]</tt> as equivalent to <tt>[2,5]</tt>.  
+<li> WeBWorK will <b>not</b> interpret <tt>[2,4]U[3,5]</tt> as equivalent
+ to <tt>[2,5]</tt>, unless a problem tells you otherwise.  
 All sets should be expressed in their simplest interval notation form, with no 
 overlapping intervals.