i>C</i>: if <i>C</i> has
now the same value <i>V</i> that it had before then there
is a cause for this.  (Intuitively, inertia is the cause; this is how
fluent dynamic laws solve the frame problem.)  These fluent dynamic laws
are similar to those obtained by expanding  <tt>may cause</tt> propositions:
they also have the form
<tt>caused</tt>&nbsp;<i>F</i>&nbsp;<tt>if</tt>&nbsp;<i>F</i>&nbsp;<tt>after</tt>&nbsp;...&nbsp;.<p>

In accordance with this understanding of inertial fluents, an
<tt>inertialFluent</tt