 a dataset D(x) which defines variable x as observable, the default logic works out as follows
<pre>
    F(x,a,b)*G(a,a0,a1) --&gt; G is constraint term (a also appears in F(x))
    F(x,a,b)*G(y,c,d) --&gt; G is dropped (factorizing term)
</pre>
  A <tt>Constrain(y)</tt> term in the above example will still force term <tt>G(y,c,d)</tt> to be interpreted as constraint term<br/><br/></li>

<li><i>Automatic caching of numeric integral calculations</i><br/>
  Integrals that require numeric integrations in two o