[gecode-users] AFC of a Propagator

[Zhu Zichen's cse]

Dear Christian,

Thanks very much!

Zoe

On Mon, Jan 26, 2015 at 9:41 PM, Christian Schulte <cschulte at kth.se> wrote:

> Hi Zoe,
>
>
>
> Here is a patch that adds a disable_afc() function to a propagator: you
> need to call it when the propagator is created and then all increments and
> are ignored. It is not tested though but should work (famous last words…).
>
>
>
> Good luck
>
> Christian
>
>
>
> --
>
> Christian Schulte, www.gecode.org/~schulte
>
> Professor of Computer Science, KTH, cschulte at kth.se
>
> Expert Researcher, SICS, cschulte at sics.se
>
>
>
> *From:* zichenzu at gmail.com [mailto:zichenzu at gmail.com] *On Behalf Of *Zhu
> Zichen's cse
> *Sent:* Friday, January 23, 2015 4:13 PM
>
> *To:* cschulte at kth.se
> *Cc:* users at gecode.org
> *Subject:* Re: [gecode-users] AFC of a Propagator
>
>
>
> Dear Christian,
>
>
>
> The case you are worried is that when p and q have the same pruning effect
> and the existence of p would make q lost some chance to increase its AFC,
> right?
>
> This case would not happen a lot because my constraint has little chance
> to have the same pruning effect with the other constraints.
>
>
>
> Actually, I would post p1 and p2 to a CSP respectively which have the same
> pruning power. But they subscribe different subsets of variables. I would
> like to compare there pruning efficiency under the similar heuristics.
>
>
>
>
>
> Zoe
>
>
>
> On Fri, Jan 23, 2015 at 10:59 PM, Christian Schulte <cschulte at kth.se>
> wrote:
>
> Dear Zoe,
>
>
>
> No, the problem is that the AFC of _ q _ is not counted properly when you
> use it together with p! Is that not a problem?
>
>
>
> Cheers
>
> Christian
>
>
>
> --
>
> Christian Schulte, www.gecode.org/~schulte
>
> Professor of Computer Science, KTH, cschulte at kth.se
>
> Expert Researcher, SICS, cschulte at sics.se
>
>
>
> *From:* zichenzu at gmail.com [mailto:zichenzu at gmail.com] *On Behalf Of *Zhu
> Zichen's cse
> *Sent:* Friday, January 23, 2015 3:57 PM
>
>
> *To:* cschulte at kth.se
> *Cc:* users at gecode.org
> *Subject:* Re: [gecode-users] AFC of a Propagator
>
>
>
> Dear Christian,
>
>
>
> You are worried that even though we do not count the AFC of p, the
> heuristic is not exactly the same with the one without posting p, right?
> It's acceptable.
>
> One reason is that my constraint does have the same pruning effect with
> other constraints in most of the cases. Another reason is that we
>
> do not require heuristics are exactly the same.
>
>
>
> So, just do not count AFC of p into its subscribed variables' AFC is
> enough.
>
>
>
>
>
> Regards,
>
> Zoe
>
>
>
>
>
> On Fri, Jan 23, 2015 at 10:28 PM, Christian Schulte <cschulte at kth.se>
> wrote:
>
> Hi Zoe,
>
>
>
> I have an idea for a fix (a hack let’s say) but I think it will not fix
> the problem you are trying to solve. Let me try to explain: when your own
> propagator p triggers failure then there are two effects. One is that the
> AFC is counted for p (this is the fix you ask for). But the other effect is
> that if p had not been there some other propagator q might have triggered
> failure and the AFC of q would have increased. But now q’s AFC will not be
> incremented.
>
>
>
> So, are you really sure that what you ask for will fix the issue? Because
> I’d hate to suggest a fix that will not solve the real problem anyway.
>
>
>
> Cheers
>
> Christian
>
>
>
> --
>
> Christian Schulte, www.gecode.org/~schulte
>
> Professor of Computer Science, KTH, cschulte at kth.se
>
> Expert Researcher, SICS, cschulte at sics.se
>
>
>
> *From:* zichenzu at gmail.com [mailto:zichenzu at gmail.com] *On Behalf Of *Zhu
> Zichen's cse
> *Sent:* Friday, January 23, 2015 11:57 AM
> *To:* cschulte at kth.se
> *Cc:* users at gecode.org
> *Subject:* Re: [gecode-users] AFC of a Propagator
>
>
>
> Dear Christian,
>
>
>
> Yes, it would be very very nice if you can help to achieve that.
>
>
>
> Zoe
>
>
>
> On Fri, Jan 23, 2015 at 5:45 PM, Christian Schulte <cschulte at kth.se>
> wrote:
>
> Hi Zoe,
>
>
>
> No, by default that is not possible. In order to do it, one would have to
> really modify the kernel of Gecode.
>
>
>
> I think you need it badly, right? If yes, I could think about it.
>
>
>
> Best
>
> Christian
>
>
>
> --
>
> Christian Schulte, Professor of Computer Science, KTH,
> www.gecode.org/~schulte/
>
>
>
> *From:* users-bounces at gecode.org [mailto:users-bounces at gecode.org] *On
> Behalf Of *Zhu Zichen's cse
> *Sent:* Friday, January 23, 2015 6:47 AM
> *To:* users at gecode.org
> *Subject:* [gecode-users] AFC of a Propagator
>
>
>
> Dear all,
>
>
>
> Is it possible to not count a propagator's AFC into its subscribed
> variables' AFC?
>
> Because now I use INT_VAR_AFC_SIZE_MAX() variable heuristic while I do not
>
> want there is a big difference on the heuristic with or without adding my
> own constraint.
>
>
>
> Many thanks.
>
>
>
>
>
> Zoe
>
>
>
>
>
>
>
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