[gecode-users] Cutting holes within a view optimally

[Zaremby, David]

Gecoders,

I am struggling with finding the best way to cut a hole in a view during propegation without doing a simple for loop. I originally thought I should use a Range and Iterator and execute the minus_v method, but I can't find an easy way to construct one easily using specific values other than using a value array of ints but I would still need a loop to initialize the array. What is the best way to do this with the least computation?

The end goal of this propagator is to put a gap between two domains however there is no guarantee that x0 < x1  so you really can't reduce much on the domain until one is assigned a start. Additionally you can't use an offset view because you only want the offset to apply if the task is the earlier one one.

virtual ExecStatus propagate(Space& home, const ModEventDelta&)  {
            if (x0.assigned())
            {
                  //create a range that x1 cant equal over (x0.val - offset1, x0.val + offset0)
                  for (int i = x0.val() - offset1; i < x0.val() + offset0; ++i)
                  {
                        GECODE_ME_CHECK(x1.nq(home, i));
                  }
            }
            else if (x1.assigned())
            {
                  //create a range that x0 cant equal over (x1.val - offset0, x1.val + offset1)
                  for (int i = x1.val() - offset0; i < x1.val() + offset1; ++i)
                  {
                        GECODE_ME_CHECK(x0.nq(home, i));
                  }
            }

            if (x0.max() + offset0 <= x1.min() || x1.max() + offset1 <= x0.min())
                  return home.ES_SUBSUMED(*this);
            else
                  return ES_FIX;
      }

David Zaremby
Senior Software Engineer
LSS / Strategic Products

Lockheed Martin Simulation, Training & Support
12506 Lake Underhill Road, MP-823
Orlando, FL 32825
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