Re: [gecode-users] Problem with constraint

[Ujhelyi Zoltan]

Hello,




I copied your code into my sample program to test, but it did not help.

I got the following result with the equality of the two variable:

Variable #1: {0..1,3,5}
Variable #2: [0..5]
Summary:
        runtime:      6
        solutions:    1
        propagations: 4
        failures:     0
        clones:       0
        commits:      0
        peak memory:  5KB
SS_SOLVED


            post(space, expression);


I used Java 1.6 in a Windows XP 32 bit system, in Eclipse environment.


Zoltán Ujhelyi

I tested the new Gecode/J 2.2.0. I am very grateful for your work, but it did not work for me as I expected. I modified the constraints as you showed, but it did not prove the required equality. I attached the my test code. If I changed to post method call (line 58-59) with the rel constraint (line 60), the result become the expected: Gecode was able to prove the equality. I also tried with a Boolean Exp BExpr expression = new BExpr(new Expr(new Expr(space.variable2).minus(space.variable1)), IRT_EQ, 0,IntConLevel.ICL_DOM); //rel(space, space.variable1, IRT_EQ, space.variable2, IntConLevel.ICL_DOM); If you could give me a hint what may I have done wrong, I would be very glad. Thank you for your help,

ExprTest.java
Description: Binary data

On 2008.08.23., at 8:56, Guido Tack wrote:

Hi!

Please let me know if this is more or less what you wanted to use:





Cheers,
        Guido

Ujhelyi Zoltan wrote:

BExpr be = new BExpr(new Expr(new Expr(space.var2).minus(space.var1)), IRT_EQ, 0, ICL_DOM); The ICL argument is now part of the BExpr, so it means that the linear constraint inside is propagated with ICL_DOM. I hope that's what you need. It will be available in Gecode/J 2.2.0 (very probably next week).

Hello,

thank you for your reply.

I understand the problem stated here, but I would like to ask whether
there is a solution to add a constraint like that to a Boolean
Expression with the domain consistent propagation (ICL_DOM).

I did not found any possibilities for that looking in the Gecode/J
API, but it would help a lot for our project.

Thank you,
Ujhelyi Zoltán
On 2008.08.11., at 11:34, Guido Tack wrote:

Could you please post to the mailing list? Thanks. Guido

Am 11.08.2008 um 11:22 schrieb Ujhelyi Zoltan:

Hello,

thank you for your reply.

I understand the problem stated here, but I would like to ask
whether there is a solution to add a constraint like that to a
Boolen Expression with the domain consistent propagation (ICL_DOM).

I did not found any possibilities for that looking in the Gecode/J
API, but it would help a lot for our project.
Thank you,
Zoltán Ujhelyi
On 2008.08.11., at 9:03, Guido Tack wrote:

Hi.

As you've already found out, you have to use domain consistent
propagation (ICL_DOM) to get the result you want.  You should be
able to use post(space, new Expr(space.variable1), IRT_EQ, new
Expr(space.variable2), ICL_DOM) to get the desired result.  I'm
not 100% sure, but I think your solution that uses e=variable1-
variable2, e=0 doesn't work because only the e=0 is propagated to
domain consistency, while e=variable1-variable2 still only
achieves bounds consistency.

Cheers,
        Guido

Ujhelyi Zoltan wrote:

Hello again,

I have been experimenting with the questions raised in my
previous mail.


both IntVars with the domain {0,5}) and three constraints:
variable1
equals variable2, and variable2 cannot have the values 2 and 4.

In all of my tests the latter two constraints are described like
that:

post(space, new BExpr(space.variable1, IRT_NQ, 2));
post(space, new BExpr(space.variable1, IRT_NQ, 4));


rel() clause to write the constraint, I got the expected result:

Variable #1: {0..1,3,5}
Variable #2: {0..1,3,5}

But when using a similar construct I would like to use in the
static
verifier, I got no result for the second variable, it can has all
values from it's domain.

post(space, new BExpr(space.variable1, IRT_EQ, space.variable2));

Reading about different propagators, I have been able to get the
expected result with the use of the ICL_DOM propagator, but only
if I
was posting the constraint directly, like that:

post(space, new Expr(space.variable1), IRT_EQ, new
Expr(space.variable2),org.gecode.GecodeEnumConstants.ICL_DOM);

But if I tried to translate the a BExprs to that form, I did not
succeed:

            Expr expression = new Expr(new
Expr(space.variable2).minus(space.variable1));
            post(space, new Expr(expression), IRT_EQ, 0,
org.gecode.GecodeEnumConstants.ICL_DOM);


meanwhile using the BExpr form, if it is possible? It would help
our
project a lot, it would simplify it's code.

Thank you for your help,
Zoltán Ujhelyi
On 2008.08.09., at 18:30, Ujhelyi Zoltan wrote:

I created a small Gecode space to be able to test the problem in a smaller scale, where I did use two variables (variable1, variable2, For the third constraint I had several tries. When I was using the Can you tell me a way how to enable this strong ICL_DOM propagators

Hello all,


interesting case.

In order to allow us greater flexibility we try to use the
Expression


I was testing the implementation, and found an interesting final
result: there were to IntVars, which were supposed to be the
same, did
not have the same final ranges: one of them had {2,4}, but the
other
had {2,3,4}. I tried to trace back the code to look whether the

building term:

BExpr expression = new BExpr(new Expr(variable1),relation, new
Expr(variable2));


values 2 and 4 (and they were the variables mentioned before in
this
letter), while the relation had the value IRT_EQ.

I tried a post of the expression right after it's construction
to see
whether it helps or not:
org.gecode.Gecode.post(space, expression);

It did not solve the problem, but when I replaced the post
method to
the following rel call, the constraint handling was working as I
expected it before.

rel(space, variable1, IntRelType.IRT_EQ, variable2);

I would like to know, whether this phenomenon is the intentional
(maybe I do not understand something under the hood), or not.
And if
you could tell me a way to avoid it, I would be very glad.

Thank you very much in advance for your help,
Zoltán Ujhelyi
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we are currently trying to build a static checker system on top of Gecode/J 2.1.1. (in an Eclipse environment), and we have found an API (it allows us to build constraints in a hierarchical manner). constraints were wrong or not, and found the following expression Tracing the variables variable1 was a new variable, it hadn't been constrained yet, while variable2's domain had been limited to the

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