OK, i see. This was indeed the thing i wanted to do. I had some bad experiences with posting propagators on unrestricted variables. Given that my supports has a declarative language for the description of the constraints, no domain is given as input. That why i wanted to compute one. But i will now leave it with a simple bound computation using boost::numeric::interval.
Thanks a lot, Max On 08/14/2012 06:52 AM, Guido Tack wrote: > Sorry but I'm not sure I understand what you're trying to do. Are you > trying to precompute bounds on the domains of a and b given that there > is a constraint a+b=c in your model? We don't have specialised > iterators for that kind of computation, and just running propagation > (i.e. calling status once) will give you the same result. You should > only restrict the variables to reasonable initial domains (i.e., use > some easy to compute upper and lower bounds). But you don't have to do > the propagators' job. > > Cheers, > Guido > > On 13/08/2012, at 8:57 PM, Max Ostrowski <ostro...@cs.uni-potsdam.de > <mailto:ostro...@cs.uni-potsdam.de>> wrote: > >> 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 <ostro...@cs.uni-potsdam.de >>> <mailto:ostro...@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...@gecode.org >>>> [mailto:users-boun...@gecode.org] On Behalf Of >>>> Max Ostrowski >>>> Sent: Thursday, July 21, 2011 10:49 AM >>>> To: users@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 >>>> >>>> _______________________________________________ >>>> Gecode users mailing list >>>> users@gecode.org <mailto:users@gecode.org> >>>> https://www.gecode.org/mailman/listinfo/gecode-users >>> >> >> _______________________________________________ >> Gecode users mailing list >> users@gecode.org <mailto:users@gecode.org> >> https://www.gecode.org/mailman/listinfo/gecode-users >
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