[gecode-users] Reified Constraints do not propagate

[Max Ostrowski]

Thanks and sorry for bugging you again.

I tried to analyze the minimodel code.
I think that posting LinExpr instead of LinRel won't change the problem,
right?
So is there any interface so that one can still use the very handy
LinExpr class?
I do parse some quite complicated formulas and want to post a linear()
constraint.
LinExpr as far as I understood, optimizes this formula and reformulates
it to fit into the form that is needed for the linear constraint.
Is there a way to get this linear constraint out of it again to post it
manually and preserve the ICL?

Or do i have to generate the linear constraint (array of variables and
numbers) myself to get the full propagation power. Is there a logical
reason why the ICL is lost during this "translation"?

Best,
Max

On 04/10/2012 01:19 PM, Christian Schulte wrote:
>
> Maybe, not so clear yet. We will change reification for the next major
> release and might at that time also think how to fix passing the
> consistency level.
>
>  
>
> For the time being you should stick to what Guido has suggested.
>
>  
>
> Christian
>
>  
>
> --
>
> Christian Schulte, www.ict.kth.se/~cschulte/
>
>  
>
> *From:* users-bounces at gecode.org [mailto:users-bounces at gecode.org] *On
> Behalf Of *Max Ostrowski
> *Sent:* Tuesday, April 10, 2012 12:42 PM
> *To:* Guido Tack
> *Cc:* users at gecode.org
> *Subject:* Re: [gecode-users] Reified Constraints do not propagate
>
>  
>
> Thank you very much for the insight.
> Unfortunately this could be a problem,
> as i have to change my data structures.
>
> Will this be fixed in future versions?
>
> Best,
> Max
>
> On 04/10/2012 12:32 PM, Guido Tack wrote:
>
> This is a current shortcoming of the minimodel library.  For some
> linear constraints (such as x==5 in this case) the IntConLevel is
> ignored.  To get the full propagation, you have to post the constraint
> directly, like this:
>
>  
>
> Gecode::rel(*test, test->x_[1], IRT_EQ, 5, test->b_[1], ICL_DOM);
>
>  
>
> Cheers,
>
> Guido
>
>  
>
> On 10 Apr 2012, at 19:20, Max Ostrowski wrote:
>
>
>
> I have a small example where i do not understand why no propagation
> takes place.
>
> test is a pointer to the space instance
> x_ is an array of 10 IntVars(0,10)
> b_ is an array of 2 BoolVars(0,1)
>
>
>     LinRel rel1(test->x_[0],IRT_EQ,5);
>     rel1.post(*test,true,ICL_DEF);
>
>     Gecode::distinct(*test,test->x_,ICL_DEF);
>
>     LinRel rel2(test->x_[1],IRT_EQ,5);
>     Gecode::rel(*test, rel2 == test->b_[1],ICL_DEF);
>
>     test->status();
>     if (test->failed())
>         std::cout << "Failed" << std::endl;
>     std::cout << test->x_ << std::endl;
>     std::cout << test->b_ << std::endl;
>
>
> So i post das one of my elements x_[0] is 5, and all elements are
> distinct.
> Now i have a reified constraint that x_[1] == 5.
> The distinct constraint removes 5 from he domain of x_[1],
>  but the propagator does not fire.
> The result is:
>
> {5, {0..4,6..10}, {0..4,6..10}, {0..4,6..10}, {0..4,6..10},
> {0..4,6..10}, {0..4,6..10}, {0..4,6..10}, {0..4,6..10}, {0..4,6..10}}
>
> {[0..1], [0..1]}
>
>
> Even with ICL_DOM the boolean variable is not touched if values are
> removed from the domain.
> Also i think this could be easily done with "Advisors" ?
> I have no experience with this, so my question:
> Is this behavior the desired one?
> Can this be changed if i have reifications like mine where i compare
> to constants?
>
> Thanks a lot,
>
> Max
>
> _______________________________________________
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>
>  
>
> -- 
>
> Guido Tack,
>
> http://www.csse.monash.edu/~guidot/
> <http://www.csse.monash.edu/%7Eguidot/>
>
>  
>
>  
>
>  
>
>  
>

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