[gecode-users] Advisor on a ViewArray and index of assigned variable

[Valentin Lemière]

Hi, 

I see, thanks for your answer. 

When an Advisor is used on a BoolView it stores the type of assignment in the delta, which can be accessed with BoolView::one and ::zero. 
But couldn't an Advisor, when applied to a ViewArray, store the index in the delta and then access it with ViewArray::index? 

With the index I can get the assigned value but not the other way around. 

It's not the case right now I understand, but do you think this is something feasible? 

Regards, 
Valentin 

----- Mail original -----

De: "Christian Schulte" <cschulte at kth.se> 
À: "Valentin Lemière" <valentin.lemiere at unicaen.fr>, users at gecode.org 
Envoyé: Lundi 9 Novembre 2015 20:20:51 
Objet: RE: [gecode-users] Advisor on a ViewArray and index of assigned variable 



Hi, 



An advisor subscribes to a particular variable implementation through a view hence, the only information that is available by default is which advisor is executed and what is the delta. 



Additional information – such as the position of an advisor in a view array – must be explicitly stored in the advisor, there is no way around it. 



Cheers 

Christian 




-- 

Christian Schulte, www.gecode.org/~schulte 

Professor of Computer Science, KTH, cschulte at kth.se 

Expert Researcher, SICS, cschulte at sics.se 





From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf Of Valentin Lemière 
Sent: Monday, November 9, 2015 04:56 PM 
To: users at gecode.org 
Subject: [gecode-users] Advisor on a ViewArray and index of assigned variable 





Hello everyone, 





I am a PhD. student and I am currently looking at Gecode to see if it'll fit my needs. 





I need to implement a global constraint on a large number of boolean variables. So I have extended from NaryPropagator with a view of type BoolView. 


When a variable is assigned, the propagator infers some knowledge and may assign other variable(s). 





To get the required information, I added an Advisor to each variable, storing its index; so I can get it in the advise method and provide it to the propagator. 


But this technique is too slow and creates too much advisors. 





So I tried adding an Advisor directly to the ViewArray; the advise function is correctly called and I can still get whether the variable was assigned a zero or a one with the delta. 


But I don't get the index information to find the actual assigned variable. 


I looked for a static method of ViewArray to convert the delta to this information but couldn't find one. 





Can an Advisor on a ViewArray get the index of the assigned variable? 


Or is there another way to deal with a large number of variables other than an Advisor per variable? 





Regards, 


Valentin 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.gecode.org/pipermail/users/attachments/20151110/c2040622/attachment.html>