Re: [eclipse-users] ``tentative'' constraints?

From: Kish Shen <kisshen_at_...5...>
Date: Mon, 12 Nov 2007 17:47:52 +0000
Ulrich Scholz wrote:
> Dear all,
>
> the repair library introduces tentative assignments to variables.  
>
> Is there a way to have ``tentative'' constraints.  In other words, is it
> possible to post a constraint, then post some others, and finally to revoke
> the first without revoking the others? 
>
> Somehow, I guess not.  But can I simulate this behaviour with ECLiPSe?
> Efficiently?
>
>
> Thanks,
>
>
> Ulrich
>   
Hi Ulrich,

It does not really make much sense to `revoke' constraints in a random 
fashion -- when a constraint is propagated, it can affect variables 
involved in other constraints, which in turn is propagated. Thus, you 
cannot simply revoke the single constraint without considering the others.

As you seem to suggest, you can simulate this by retracting all the 
constraints which might change, and then re-posting the subset of 
constraints you are interested in. If you want to avoid local 
propagation as you post each constraint, you can adjust the priority of 
the constraints as you post the constraints to avoid the local propagation.

Cheers,

Kish
Received on Mon Nov 12 2007 - 17:48:11 CET

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