[gecode-users] Propagating to Fixpoint

[Max Ostrowski]

Actually its quite complicated.
I'm currently debugging and have 60 constraints written on paper that
have this effect.
Two of them are actually not reified constraints but directly using
IntView::lq(constant)

I can give you a description where it happens in my system, but it will
be a mess for you to write simplified code that reproduces this.

Actually given two spaces original1 and original2 that are equal,
variables are constraint like this:

posx(6)=[0..185] posx(5)=[0..190] posx(4)=[0..142] posx(3)=[0..158]
posx(2)=[0..113] posx(1)=[0..157]


all reified constraints are posted with free boolean variables, using



linear(*this, intArgs, intVarArgs, r,0,b_[boolvar],ICL_DEF);

Now i set the boolean variables accordingly, always doing propagation
(calling status()) after each single posting

To original1 false ((-1 $* posx(3))+posx(1))$<=0

To original1 false ( 10+(-1 $* posx(6))+posx(5))$>0
To original1 false ( 58+(-1 $* posx(5))+posx(4))$>0
To original1 true posx(6)<=69                            // this is no
reified constraint, but just posted IntView(posx(6)).lq(69)
To original1 false ( 43+(-1 $* posx(6))+posx(1))$>0
To original1 false ((-1 $* posx(5))+posx(2))$<=0
To original1 true ((-1 $* posx(1))+posx(3))$<=0
To original1 true ((-1 $* posx(4))+posx(3))$<=0
To original1 false ( 42+(-1 $* posx(5))+posx(3))$>0
To original1 false ( 42+(-1 $* posx(6))+posx(3))$>0
To original1 true ( -42+(-1 $* posx(3))+posx(1))$<0
To original1 true ( -15+(-1 $* posx(6))+posx(1))$<0
To original1 true ( 58+(-1 $* posx(1))+posx(4))$>0
To original1 true ( 42+(-1 $* posx(1))+posx(3))$>0
To original1 false ((-1 $* posx(1))+posx(2))$<=0
To original1 true ((-1 $* posx(6))+posx(1))$<=0
To original1 true ((-1 $* posx(5))+posx(1))$<=0
To original1 true ( -10+(-1 $* posx(5))+posx(1))$<0
To original1 true ((-1 $* posx(2))+posx(1))$<=0
To original1 false ( 43+(-1 $* posx(2))+posx(1))$>0
To original1 true ( -28+(-1 $* posx(1))+posx(6))$>0
To original1 false ( 28+(-1 $* posx(6))+posx(1))$>0
To original1 false ( -43+(-1 $* posx(1))+posx(2))$<0
To original1 true ( -58+(-1 $* posx(4))+posx(1))$<0
To original1 true posx(1)<=29                          // this is no
reified constraint, but just posted IntView(posx(1)).lq(29)
To original1 false ((-1 $* posx(1))+posx(4))$<=0       // lets call this
constraint X

Now this space is failed.

Something similar with the second space, but posting nr. 5 is different.

To original2 false ((-1 $* posx(3))+posx(1))$<=0
To original2 false ( 10+(-1 $* posx(6))+posx(5))$>0
To original2 false ( 58+(-1 $* posx(5))+posx(4))$>0
To original2 false ((-1 $* posx(1))+posx(4))$<=0       // this is
constraint X, it is now posted on this position, no longer as the last
constraint anymore
To original2 true posx(6)<=69                          // this is no
reified constraint, but just posted IntView(posx(6)).lq(69)
To original2 false ( 43+(-1 $* posx(6))+posx(1))$>0
To original2 false ((-1 $* posx(5))+posx(2))$<=0
To original2 true ((-1 $* posx(1))+posx(3))$<=0
To original2 true ((-1 $* posx(4))+posx(3))$<=0
To original2 false ( 42+(-1 $* posx(5))+posx(3))$>0
To original2 false ( 42+(-1 $* posx(6))+posx(3))$>0
To original2 true ( -42+(-1 $* posx(3))+posx(1))$<0
To original2 true ( -15+(-1 $* posx(6))+posx(1))$<0
To original2 true ( 58+(-1 $* posx(1))+posx(4))$>0
To original2 true ( 42+(-1 $* posx(1))+posx(3))$>0
To original2 false ((-1 $* posx(1))+posx(2))$<=0
To original2 true ((-1 $* posx(6))+posx(1))$<=0
To original2 true ((-1 $* posx(5))+posx(1))$<=0
To original2 true ( -10+(-1 $* posx(5))+posx(1))$<0
To original2 true ((-1 $* posx(2))+posx(1))$<=0
To original2 false ( 43+(-1 $* posx(2))+posx(1))$>0
To original2 true ( -28+(-1 $* posx(1))+posx(6))$>0
To original2 false ( 28+(-1 $* posx(6))+posx(1))$>0
To original2 false ( -43+(-1 $* posx(1))+posx(2))$<0
To original2 true ( -58+(-1 $* posx(4))+posx(1))$<0
To original2 true posx(1)<=29                                        //
this is no reified constraint, but just posted IntView(posx(1)).lq(29)

This Space is not failed




I know this is quite a huge blob of data and you probably wont have the
time to reconstruct it.
I will just have to adjust my code that this can happen.
BTW: Can you confirm that this is due to the use of IntView::lq ?
I never experienced this without them.

Best,
Max




On 08/23/2012 12:40 PM, Guido Tack wrote:
> I guess under certain conditions the code that posts the constraints (not the actual propagator) can be stronger than ICL_DEF, in which case this can happen.
> If it's not too complicated, could you send us a concrete example?
>
> Cheers,
> Guido
>
>   

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