[gecode-users] question about 'element' constraint

[Stefano Gualandi]

Hi,
I am observing a strange behavior with the element constraint with 
domain consistency, when the vector is an array of variables (i.e., 
using doc notation: x_y0 = y1). For instance, in the attached script, 
it enlarges the domain of y1.

Any hints?

Please notice, that it works if we use bound consistency (ICL_BND).

thanks in advance,
Stefano

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#include "support.hh"

class MyModel : public Example {

private:
  IntVarArray xs;
  IntVarArray ys;
  IntVarArray ts;

public:
  MyModel(const Options& o)
    : xs(this, 3, 0, 2), ys(this, 6, 13, 30), ts(this, 6, 10, 20)
  {
    element(this, ts, xs[0], ys[0], ICL_DOM); // or ICL_BND

    branch(this, xs, BVAR_SIZE_MIN, BVAL_MIN);
  }

  MyModel(bool share, MyModel& s) : Example(share,s) {
    xs.update(this, share, s.xs);
    ys.update(this, share, s.ys);
    ts.update(this, share, s.ts);
  }

  virtual Space*
  copy(bool share) {
    return new MyModel(share, *this);
  }

  virtual void
  print(void) {
    for (int i = 0; i < xs.size(); i++) 
      std::cout << "\t x: " << xs[i] << " - y: " << ys[i] << " - t: " << ts[i] << std::endl;

    std::cout << std::endl;
  }
};

int
main(int argc, char** argv) {
  Options opt("New Model");

  opt.n          = 6;
  opt.iterations = 200;
  opt.c_d        = 5;
  opt.parse(argc,argv);

  Example::run<MyModel,DFS<MyModel> >(opt);
  return 0;
}
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