Hi Milt,
just posting a constraint does not mean it is "executed". Running search for
your problem (or, in fact, just calling status() on the space you post the
constraints in) should determine that ds[0]=1. See Tip 2.2 "Propagation is
explicit" in Modeling and Programing with Gecode.
Cheers,
Guido
On 18 Nov 2011, at 02:28, Milton Friedman wrote:
> I've been learning and coding in Gecode for the past few weeks. I read and
> re-read the modeling parts of MPG, and checked the online docs for syntax.
>
> I've tried recasting my application several times and each time I get blocked
> by syntax I'd expect to exist that doesn't.
>
> I hardly ever seem to have a reification-suitable situation, and when I do,
> it's with a function that doesn't support reification.
>
>
> I'm used to languages that let you put data in arrays and then index into the
> arrays to solve problems. The Gecode examples seem to have variable arrays,
> and constant integer indices into them, based on a fixed problem structures,
> like Sudoku etc., but in my case the application structure that's constant is
> the array, and the parts of it that I need to index into are determined by
> the finite-domain variables.
>
>
>
> Below is an example. I'm trying to use an IntVarArgs to index into a vector
> of constants (in this case booleans).
>
> I can't figure out how to get Gecode to index directly into the C++ vector,
> so I create a BoolVarArgs vector and copy the constants into it...seems
> wasteful but ok.
>
> Then I do the indexing into a vector of constants, with a single number
> (1-item domain), and it tells me the binary result is [0..1] -- not
> especially enlightening news about a binary.
>
> So I must be missing something obvious about how to index in Gecode. Any
> thoughts?
>
> Any help or guidance would be appreciated.
>
> Thanks,
>
> -Milt
>
>
>
> //notCD is a C++ boolean vector: knows nothing about Gecode
>
> bool * notCD
>
> notCD = new bool [VecLength];
>
> for (int i = 0; i<VecLength; i++) {
>
> notCD[i] = abs(some2D_integer_array[i][2])==1;
>
> }
>
> //Create nCD: BoolVarArgs vector of notCD //only creating nCD
> because I can't get Gecode to let me work directly with notCD
>
> BoolVarArgs nCD(VecLength);
>
> for(int i=0; i<VecLength; i++){ //expected to write nCD[i]=notCD[i];
> or maybe nCD[i]=expr(*this,notCD[i]); or nCD[i]=expr(*this,element(notCD,i));
>
> // but none of these forms compiled
>
> if (notCD[i]){
>
> nCD[i]=T;
>
> }
>
> else {
>
> nCD[i]=F;
>
> }
>
> }
>
> //I'm really just trying to index with an item of an IntVarArgs
> vector into a C++ boolean vector
>
> IntVar da;
>
> for(int i=0; i<3; i++){
>
> da = p[iterm+i]; //p is an IntVarArgs with all terms
> assigned, and p[iTerm+0] is 192
>
> ds[i] = expr(*this,element(nCD,da),ICL_DOM);
>
> cout<<"da: "<<da<<", ds["<<i<<"]: "<<ds[i]<<", nCD[192]:
> "<<nCD[192]<<" ";
>
> }
>
> //-------------------
>
> //so unfortunately the output is:
>
> //da: 192, ds[0]: [0..1], nCD[192]: 1
>
> //
>
> //why isn't the output:
>
> //da: 192, ds[0]: 1, nCD[192]: 1
>
> //why is there indecision about ds[0]?...how do I get Gecode to
> understand that ds[0] must be 1?
>
> _______________________________________________
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--
Guido Tack, http://people.cs.kuleuven.be/~guido.tack/
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