[gecode-users] Extra level of variables needed for count?

[Christian Schulte]

Yep, that looks good. Gecode will choose the most efficient representation anyway at runtime. Cheers Christian

--
Christian Schulte, https://chschulte.github.io/
Professor of Computer Science, KTH, cschulte at kth.se<mailto:cschulte at kth.se>
Expert Researcher, RISE SICS, christian.schulte at ri.se<mailto:christian.schulte at ri.se>

From: Neill Clift <NeillClift at live.com>
Sent: 12 March 2018 18:28
To: Christian Schulte <cschulte at kth.se>; users at gecode.org
Subject: RE: Extra level of variables needed for count?

Thanks.
I think I might now be seeing what you are saying. Sorry to be so stupid. I found this count stuff to be mind boggling.

                                IntSetArgs s((LPTYPER)bp.MaxBit);
                                for (LPTYPER i = 0; i < (LPTYPER)bp.MaxBit; i++) {
                                                s[i] = IntSet((LPTYPER)bp.Bits[i], (LPTYPER)bp.Bits[i]);
                                }
                                count(*this, b, s, IPL_DOM);

I guess I was feeling I was using an overly more general mechanism with variables for counts when I have constants for counts. With the sets I am still using something which allows much more general situations but since it’s constants it might be optimized away.
So I assume this would be the recommended way to code this?
Neill.

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________________________________
From: Christian Schulte <cschulte at kth.se<mailto:cschulte at kth.se>>
Sent: Monday, March 12, 2018 9:31:36 AM
To: Neill Clift; users at gecode.org<mailto:users at gecode.org>
Subject: RE: Extra level of variables needed for count?

No, the point is to not use variables, you can use sets with a single element instead. Christian

--
Christian Schulte, https://chschulte.github.io/
Professor of Computer Science, KTH, cschulte at kth.se<mailto:cschulte at kth.se>
Expert Researcher, RISE SICS, christian.schulte at ri.se<mailto:christian.schulte at ri.se>

From: Neill Clift [mailto:NeillClift at live.com]
Sent: Monday, March 12, 2018 17:30
To: Christian Schulte <cschulte at kth.se<mailto:cschulte at kth.se>>; users at gecode.org<mailto:users at gecode.org>
Subject: RE: Extra level of variables needed for count?

OK thanks for that. This makes the code simpler but I do still have to make a set of variables to contain the multiplicities (the v’s).
Of course they immediately become assigned to a single value. Would it be right in assuming the cost of that on the model is very small?

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________________________________
From: Christian Schulte <cschulte at kth.se<mailto:cschulte at kth.se>>
Sent: Monday, March 12, 2018 2:31:26 AM
To: Neill Clift; users at gecode.org<mailto:users at gecode.org>
Subject: RE: Extra level of variables needed for count?

Hi,

I think you stopped reading a little too early. MPG says that you can also use integer sets instead of variables.

Then, in your example you do not need x and c, just pass b and v directly! IntVarArray is automatically casted to IntVarArgs.

Cheers
Christian

--
Christian Schulte, https://chschulte.github.io/
Professor of Computer Science, KTH, cschulte at kth.se<mailto:cschulte at kth.se>
Expert Researcher, RISE SICS, christian.schulte at ri.se<mailto:christian.schulte at ri.se>

From: users-bounces at gecode.org<mailto:users-bounces at gecode.org> [mailto:users-bounces at gecode.org] On Behalf Of Neill Clift
Sent: Saturday, March 10, 2018 20:37
To: users at gecode.org<mailto:users at gecode.org>
Subject: [gecode-users] Extra level of variables needed for count?

Hi,
I want to restrict the values of an array to members of a multiset. This is a bit like distinct but can have repeated values.
So for example I want the values of b[0..7] to come from the multiset {5,5,5,4,3,2,1,0}. The b’s are essentially a permutation of the multiset
Count seems to be the way to achieve this but I have to add a whole new set of variables (the v’s below) that contain the counts of the multiplicities.
I cut out a bunch of stuff that’s not relevant to the code below so I hope it still makes  sense.
bp.MaxBit is the number of distinct values in the multiset. And bp.Bits[i] is the multiplicity for the multiset value i.
Is this the expected way to do what I am trying to do here?
Thanks.
Neill.

public:
                IntVarArray b;

public:
                PartialOrderSort(LPTYPER n, BIT_PATTERN &bp, LPTYPER TopIndex) :
                                b(*this, n, 0, TopIndex)
                {
                                IntVarArgs x(n);
                                IntVarArgs c((LPTYPER)bp.MaxBit);
                                for (int i = 0; i < n; i++) {
                                                x[i] = b[i];
                                }
                                IntVarArray v(*this, (LPTYPER)bp.MaxBit, 0, n - 1);
                                for (int i = 0; i < bp.MaxBit; i++) {
                                                c[i] = v[i];
                                                rel(*this, v[i] == (LPTYPER)bp.Bits[i]);
                                }

                                count(*this, x, c, IPL_DOM);


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