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,  <http://www.gecode.org/~schulte> www.gecode.org/~schulte 

Professor of Computer Science, KTH,  <mailto:cschu...@kth.se> cschu...@kth.se

Expert Researcher, SICS,  <mailto:cschu...@sics.se> cschu...@sics.se

 

From: users-boun...@gecode.org [mailto:users-boun...@gecode.org] On Behalf Of 
Valentin Lemière
Sent: Monday, November 9, 2015 04:56 PM
To: users@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

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