A step is a pair of 
 <A HREF = "states.html">states</A>.

<P> For any 
 <A HREF = "action.html">action</A>
<CODE>A</CODE>, an <EM><CODE>A</CODE>-step</CODE> is a step
that satisfies <CODE>A</CODE>.

<P>
The steps of the
 <A HREF = "behavior.html">behavior</A> 
<PRE>
  s , s , s , ...
   1   2   3
</PRE>
are the pairs 
<PRE>
  &lt;s , s &gt; ,  &lt;s , s &gt; ,  &lt;s , s &gt ,  ...
    1   2       2   3       3   4
</PRE>