[WWcvs] webwork-modperl: Update interval notation information for students based

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

Log Message:
-----------
Update interval notation information for students based on recent
improvements in the Parser.

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 1.2
retrieving revision 1.3
diff -Lhtdocs/helpFiles/IntervalNotation.html -Lhtdocs/helpFiles/IntervalNotation.html -u -r1.2 -r1.3
--- htdocs/helpFiles/IntervalNotation.html
+++ htdocs/helpFiles/IntervalNotation.html
@@ -11,15 +11,18 @@
 
 <ul>
 
-<li> If an endpoint is included, then use <tt>[</tt> or <tt>]</tt>.  If not, then use <tt>(</tt> or <tt>)</tt>.  For example, the interval from
--3 to 7 that includes 7 but not -3 is expressed <tt>(-3,7]</tt>.
+<li> If an endpoint is included, then use <tt>[</tt> or <tt>]</tt>.
+If not, then use <tt>(</tt> or <tt>)</tt>.  For example, the interval
+from -3 to 7 that includes 7 but not -3 is expressed <tt>(-3,7]</tt>.
 
 <br>
 <br>
 
-<li> For infinite intervals, use <tt>Inf</tt> for <font size="+2">&#8734;</font> (infinity) and/or 
-<tt>-Inf</tt> for <font size="+2">-&#8734;</font> (-Infinity).  For example, the infinite interval containing all points greater than 
-or equal to 6 is expressed <tt>[6,Inf)</tt>.
+<li> For infinite intervals, use <tt>Inf</tt>
+for <font size="+2">&#8734;</font> (infinity) and/or
+<tt>-Inf</tt> for <font size="+2">-&#8734;</font> (-Infinity).  For
+example, the infinite interval containing all points greater than or
+equal to 6 is expressed <tt>[6,Inf)</tt>.
 
 <br>
 <br>
@@ -30,6 +33,21 @@
 <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>.
+
+<br>
+<br>
+
+<li> You can use set difference notation.  So, for all real numbers
+  except 3, you can use <code>R-{3}</code> or
+  <code>(-Inf, 3)U(3,Inf)</code> (they are the same).  Similarly,
+  <code>[1,10)-{3,4}</code> is the same as <code>[1,3)U(3,4)U(4,10)</code>.
+
+<br>
+<br>
+
+
 <li> WeBWorK will not interpret <tt>[2,4]U[3,5]</tt> as equivalent to <tt>[2,5]</tt>.  
 All sets should be expressed in their simplest interval notation form, with no 
 overlapping intervals.