BTW,

To solve Nil's problem, I invented the AnyNode.  I use it like this:

EvaluationLink  tv
   BlahNode
   ListLink
       BlahBlahNode
       AnyNode

The EvaluationLink tv then holds a count which is a sum over all other EvaluationLinks that look like this, with a different Node where the AnyNode is.   This, to me, seems to be a simpler, better solution, than the one that Nil was proposing -- in particular, it does not require inventing a new truth value type.