[gecode-users] Cutting holes within a view optimally

[Christian Schulte]

Check the minus_r member function and the range iterator

                Iter::Ranges::Singleton

The latter allows to specify a single range.

 

That should do the trick!

 

Cheers

Christian

 

--

Christian Schulte, web.ict.kth.se/~cschulte/

 

From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Zaremby, David
Sent: Tuesday, April 13, 2010 7:34 PM
To: users at gecode.org gecode
Subject: [gecode-users] Cutting holes within a view optimally

 

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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