There are several problems with this rule.
The notion of a slot of some fact being bound doesn't make sense. A slot
always has a value, possibly nil, and you can simply compare a slot to
this symbol.
You cannot simply write a boolean function as another term in a
rule's LHS. So, the (< ...) must be wrapped in a test, but it would be better
to have this test in the pattern for the currentTimeStep fact.
The two opening parentheses after "=>" are in error.
You cannot - and need not - re-assert ?Outcome. Use the modify function
to update a fact's slot value, e.g.,
(modify ?Outcome (time ?T))
Please consult the Jess manual for more detailed explanations.
-W
On Tue, Oct 7, 2008 at 9:59 AM, David Pautler <[EMAIL PROTECTED]> wrote:
> How can one test if a var is bound or not bound (rather than testing if it's
> bound or not to a specific value)?
>
> For example, I would like to write something like this:
>
> (defrule causation-1
> "When a causal trigger is present, the outcome occurs"
> (and (cause (trigger ?Trigger) (outcome ?Outcome))
> (test (not (bound ?Outcome.time))) ;test of
> whether ?Outcome.time is bound
> (currentTimeStep ?T)
> (< ?Trigger.time ?T) )
> =>
> ((assert ?Outcome)
> (bind ?Outcome.time ?T) ))
>
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