This can all be combined in a single rule without a "foreach" loop.
(defrule manage-source-templates
"Logically assert or retract templates for source"
(logical (source (id ?id) (templates $? ?template $?)))
(not (transform (source ?id) (template ?template)))
=>
(assert (transform (source ?id) (template ?template))))
Bob Kirby
At 09:11 AM 9/7/2007, Ernest Friedman-Hill wrote:
>Same idea:
>
>(defrule removeTransforms
> ?t <- (transform (source ?id) (template ?t))
> (not (source (id ?id)(templates $? ?t $?))
>=>
> (retract ?t))
>
>
>On Sep 7, 2007, at 11:57 AM, Hal Hildebrand wrote:
>>Doh! That does work well and I'll certainly replace my cheesy
>>solution with this, but one of the issues I'm dealing with is that the set of
>>templates can change and I would like to ensure that as changes to the list
>>of templates occur, the corresponding transforms are asserted or
>>retracted.
>>Sorry, this is an additional constraint I would like to satisfy that I
>>should have noted.
>>
>>
>>On 9/7/07 8:28 AM, "Wolfgang Laun" <[EMAIL PROTECTED]>
>>wrote:
>>>Assuming that the absence of any "transform" fact with a "source"
>>>slot equal to the "id" slot of a new "source" fact is the criterion for
>>>creating the "transform" facts:
>>>
>>>(defrule makeTransforms
>>> ?s <- (source (id ?id)(templates $?templates))
>>> (not (transform (source ?id)))
>>>=>
>>> (foreach ?temp $?templates
>>> (assert (transform (source ?id) (template ?temp))))
>>>)
>>>
>>>kr
>>>Wolfgang
>>>
>>>Hal Hildebrand wrote:
>>>>I have a system where I need to ensure that for every member of a
>>>>list, there is a fact which contains that member. For example, here's
>>>>my domain:
>>>>
>>>>
>>>>(deftemplate source (slot id) (multislot templates))
>>>>(deftemplate transform (slot source) (slot template))
>>>>
>>>>
>>>>What I would like is to write some rules that ensure that for ever member
>>>>of the templates slot of a "source", I have a corresponding transform. If
>>>>I assert:
>>>>
>>>>(assert source (id 1) (templates (create$ a b c)))
>>>>
>>>>I would like to see three facts asserted in response:
>>>>
>>>>(assert transform (source 1) (template a))
>>>>(assert transform (source 1) (template b))
>>>>(assert transform (source 1) (template c))
>>>>
>>>>
>>>>I have accomplished this by creating an intermediary fact and some rules
>>>>which essentially cycle through the list of templates in the source,
>>>>asserting a transform for each. However, this just feels wrong. It seems
>>>>like I should be able to express this without the intermediary facts.
>>>>
>>>>Perhaps this is where backward chaining would be useful? Or perhaps I can
>>>>use the new "accumulate" CE? Or, have I already found the solution using
>>>>an intermediary fact to cycle through the list of templates?
>>>>
>>>>Any help/suggestions would be appreciated.
>
>---------------------------------------------------------
>Ernest Friedman-Hill
>Advanced Software Research Phone: (925) 294-2154
>Sandia National Labs FAX: (925) 294-2234
>PO Box 969, MS 9012 [EMAIL PROTECTED]
>Livermore, CA 94550 http://www.jessrules.com
