[gecode-users] Question on IntVar-equalities with and without MiniModel
Christian Schulte
cschulte at kth.se
Tue Mar 14 11:11:24 CET 2017
Hi Conrad, I just added this behavior in the trunk! Cheers Christian
--
Christian Schulte, www.gecode.org/~schulte
Professor of Computer Science, KTH, <mailto:cschulte at kth.se>
cschulte at kth.se
Expert Researcher, RISE SICS, <mailto:christian.schulte at ri.se>
christian.schulte at ri.se
From: Drescher, Conrad [mailto:conrad.drescher at sap.com]
Sent: Monday, March 13, 2017 13:14
To: cschulte at kth.se; users at gecode.org
Subject: RE: [gecode-users] Question on IntVar-equalities with and without
MiniModel
Hi Christian,
thanks a lot, that looks very good! For us, I don’t see a use case for
stronger reified variants
Best wishes,
Conrad
Dr. Conrad Drescher
Senior Developer | Variant Configuration
P&I S/4HANA Idea – LoB Research & Development
SAP SE | Dietmar-Hopp-Allee 16 | 69190 Walldorf | Germany
T +49 6227 7-77888 | M +49 160 90684883 | E conrad.drescher at sap.com
<http://www.sap.com/> www.sap.com
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From: Christian Schulte [mailto:cschulte at kth.se]
Sent: Montag, 13. März 2017 13:08
To: Drescher, Conrad <conrad.drescher at sap.com>; users at gecode.org
Subject: RE: [gecode-users] Question on IntVar-equalities with and without
MiniModel
Hi Conrad,
I just had a look at the code and the second option seems to be quite easy
to do. The candidates for domain consistent propagation would be:
- x = y, x = -y
- x + y = c, x – y = c (provided that x, y, c do not exceed some
limit)
However, getting also the reified variants domain consistent would require
some (not much) work. Would that be needed as well?
Cheers
Christian
--
Christian Schulte, www.gecode.org/~schulte
Professor of Computer Science, KTH, <mailto:cschulte at kth.se>
cschulte at kth.se
Expert Researcher, RISE SICS, <mailto:christian.schulte at ri.se>
christian.schulte at ri.se
From: Drescher, Conrad [mailto:conrad.drescher at sap.com]
Sent: Monday, March 13, 2017 10:22
To: users at gecode.org
Cc: cschulte at kth.se
Subject: RE: [gecode-users] Question on IntVar-equalities with and without
MiniModel
Hi Christian,
I had not even thought of the first option
the second option should be
easily sufficient for our purposes. If it were possible to make that special
case of “x == y” behave like “x IRT_EQ y” that would really benefit our use
case. We have no interest in using DOM for the general case of “IntExpr1 ==
IntExpr2”.
Many thanks for considering the idea, and the great software in general!
Conrad
Dr. Conrad Drescher
Senior Developer | Variant Configuration
P&I S/4HANA Idea – LoB Research & Development
SAP SE | Dietmar-Hopp-Allee 16 | 69190 Walldorf | Germany
T +49 6227 7-77888 | M +49 160 90684883 | E conrad.drescher at sap.com
<http://www.sap.com/> www.sap.com
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From: Christian Schulte [mailto:cschulte at kth.se]
Sent: Montag, 13. März 2017 09:41
To: Drescher, Conrad <conrad.drescher at sap.com>; users at gecode.org
Subject: RE: [gecode-users] Question on IntVar-equalities with and without
MiniModel
Hmmm, not that straightforward. There are two ideas here:
- One idea would be that there is an additional IPL (integer
propagation level) called something like IPL_CHEAP_DOM which does domain
propagation only if it is cheap.
- The other idea would be that linear interprets the default IPL
ILP_DEF differently: normally it uses IPL_BND but for special cases it uses
IPL_DOM.
The second might be easier to pull off
Cheers
Christian
--
Christian Schulte, <http://www.gecode.org/~schulte> www.gecode.org/~schulte
Professor of Computer Science, KTH, <mailto:cschulte at kth.se>
cschulte at kth.se
Expert Researcher, RISE ICT/SICS, <mailto:cschulte at sics.se>
cschulte at sics.se
From: <mailto:users-bounces at gecode.org> users-bounces at gecode.org [
<mailto:users-bounces at gecode.org> mailto:users-bounces at gecode.org] On Behalf
Of Drescher, Conrad
Sent: Friday, March 10, 2017 09:47
To: <mailto:users at gecode.org> users at gecode.org
Subject: [gecode-users] Question on IntVar-equalities with and without
MiniModel
Hi there,
I have a question on the „equal“ constraint between two IntVars, let’s say
x0 with domain [1,3,5], and x1 with domain
[Int::Limits::min..Int::Limits::max].
If I write rel(home,x0,IRT_EQ,x1); x1 gets restricted to [1,3,5] as IRT_EQs
default propagation level is IPL_DOM. But if I write rel(home,x0 == x1);
using MiniModel x1 gets restricted to [1 – 5].
Apparently equalities between linear integer expressions get summarized into
a “linear” constraint in MiniModel, which of course is nice. This linear
constraint in turn seems to have a lot of special cases covered (which I
haven’t fully grasped yet). But I wonder whether it’d be possible to get the
case of there being just two variables back up to IPL_DOM instead of
IPL_BND? Of course, I understand you wouldn’t want to have IPL_DOM for
linear in general
Many thanks!
Conrad
Dr. Conrad Drescher
Senior Developer | Variant Configuration
P&I S/4HANA Idea – LoB Research & Development
SAP SE | Dietmar-Hopp-Allee 16 | 69190 Walldorf | Germany
T +49 6227 7-77888 | M +49 160 90684883 | E
<mailto:conrad.drescher at sap.com> conrad.drescher at sap.com
<http://www.sap.com/> www.sap.com
Please consider the impact on the environment before printing this e-mail.
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Dank.
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