[gecode-users] Computing Variable Domains

[Max Ostrowski]

Thank you very much for the fast answer.
I tried to play around with them but still face a lot of problems.

In the documentation
http://www.gecode.org/doc-latest/reference/group__FuncIterRangesVirt.html it
is written that
"Iterators with virtual member functions have to be used when they are
combined dynamically ..."
The only base class i found is MinMax.

So how can i use the iterator dynamically.
In the given example i have to know the type of the iterator used before.
(To build the intersection of two Singletons for example)
But if i want to build the intersection of two "domains" which could
have been constructed in various ways (for example recursively),
i need to have a general Base Type, right ?
Is the Iter::Ranges thing still the right thing to use or is there
something else.

Also i found only iterators for union/intersection etc...
Given that you want to add two variables a and b with known domain
(stored in a RangeList?), how do you compute the domain of the result.
Is there any functionality for this or do i have to iterate through both
lists of ranges and add them together to form a new list.


I hope i made things clear, if not please ask.


Best,
Max


On 08/10/2012 06:44 AM, Guido Tack wrote:
> Hi,
>
> here's some code that will do what you want:
>
>       Iter::Ranges::Singleton si00(6,Int::Limits::max);
>       Iter::Ranges::Singleton si10(Int::Limits::min,9);
>      
> Iter::Ranges::Inter<Iter::Ranges::Singleton,Iter::Ranges::Singleton> 
>         inter0(si00,si10);
>
>       Iter::Ranges::Singleton si01(101,Int::Limits::max);
>       Iter::Ranges::Singleton si11(Int::Limits::min,104);
>      
> Iter::Ranges::Inter<Iter::Ranges::Singleton,Iter::Ranges::Singleton> 
>         inter1(si01,si11);
>
>       Iter::Ranges::Union<
>        
> Iter::Ranges::Inter<Iter::Ranges::Singleton,Iter::Ranges::Singleton>,
>        
> Iter::Ranges::Inter<Iter::Ranges::Singleton,Iter::Ranges::Singleton> > 
>         u(inter0,inter1);
>
>       IntVar a(*this,IntSet(u));
>
> You can also use the n-ary variants of the iterators if you need to
> compute a union or intersection of more than two sets.
>
> Cheers,
> Guido
>
> On 08/08/2012, at 9:41 PM, Max Ostrowski <ostrowsk at cs.uni-potsdam.de
> <mailto:ostrowsk at cs.uni-potsdam.de>> wrote:
>
>> Sorry for reposting an old question. I'm just cleaning up my code and
>> noticed that i still not managed to use gecode's functionality to
>> precompute domains of IntVar.
>> So, given a constraint "(a>5 /\ a<10) \/ (a>100 /\ a<105)"
>> I want to precompute the domain of "a".
>> I'm simply not able to find out how the Ranges iterators are used.
>> How to i create a range "5..inf" and a range "-inf..10"
>> How do i create the intersection of both.
>> And finally how to set the domain of IntVar x to this range then.
>>
>>
>> I tried to grep the gecode code and the examples but was not able to
>> find any.
>>
>> Sorry again for reposting this, i'm ashamed.
>>
>> Best,
>> Max
>>
>>
>>
>>
>>
>>     The best is to look for examples in the code ;-) Just grep for it.
>>
>>     MinMax is nothing but a base-class for other classes and cannot
>>     be used
>>     directly. Look for the iterators that take arrays as input, they
>>     will do what
>>     you want.
>>
>>     Best
>>     Christian
>>
>>     --
>>     Christian Schulte, KTH, web.it.kth.se/~cschulte/
>>     <http://web.it.kth.se/%7Ecschulte/>
>>
>>     -----Original Message-----
>>     From: users-boun... at gecode.org [mailto:users-boun... at gecode.org]
>>     On Behalf Of
>>     Max Ostrowski
>>     Sent: Thursday, July 21, 2011 10:49 AM
>>     To: users at gecode.org
>>     Subject: [gecode-users] Computing Variable Domains (Integer)
>>
>>     Hello everybody,
>>
>>     as variables in gecode need to have a domain, i want to compute
>>     the domain of
>>     the variables automatically, given the constraints.
>>     I could also let the constraints restrict the domains of my
>>     variables, but as i
>>     understood, this is similar to propagation and could take some time.
>>     There i want to restrict the domain manually for all unary
>>     constraints.
>>     So, given a constraint "(a>5 /\ a<10) \/ (a>100 /\ a<105)"
>>     the domain should be {6..9,101..104}.
>>     Therefore i wanted to use some Gecode classes to compute the
>>     intersection/union/complement etc.. of the sets.
>>     Am i right that i can use the Int::Iter::Ranges classes for this?
>>     And second, how do they work?
>>     So in this case, i would create a
>>
>>     IntSet a1(Gecode::Iter::Ranges::MinMax(5+1,Int::Limits::max));
>>     IntSet a2(Gecode::Iter::Ranges::MinMax(Int::Limits::min, 10-1));
>>
>>     And them somehow the intersection of this.
>>     But i was neither able to initialize a set with a Range, nor to
>>     combine Ranges
>>     recursively.
>>
>>     So, how do i do this using the helping classes of gecode.
>>
>>     Best,
>>     Max
>>
>> _______________________________________________
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>> users at gecode.org <mailto:users at gecode.org>
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>

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