[gecode-users] AFC decay with global AFC in search engines

[Christian Schulte]

Hi Kish, changed in the trunk. Cheers Christian

--
Christian Schulte, Professor of Computer Science, KTH,
www.ict.kth.se/~cschulte/


-----Original Message-----
From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
Of Kish Shen
Sent: Friday, May 23, 2014 7:40 PM
To: users at gecode.org
Subject: Re: [gecode-users] AFC decay with global AFC in search engines

Hi Christian,

To me, legal but not sensible values should be allowed -- some of the
variable and value selection strategies implemented by Gecode probably are
not very sensible also. In addition, the AFC decay factor can be set to 0
already using afc_decay(0.0), so making the initialision of an IntAFC
consistent with that seems reasonable to me.

Also, the decay factor for IntActivity can be set to 0, although I guess it
might make more sense here, as AFC is only changed when a failure occurs.

Cheers,

Kish

On 23/05/2014 08:49, Christian Schulte wrote:
> Hi Kish,
>
> Yes, a decay factor of zero makes normally no sense. If you want me 
> to, I can change that.
>
> Yes, you are right, there is only one global AFC decay factor.
>
> Cheers
> Christian
>
> Christian Schulte, KTH, web.it.kth.se/~cschulte/
>
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On 
> Behalf Of Kish Shen
> Sent: Friday, May 23, 2014 04:13 AM
> To: users at gecode.org
> Subject: Re: [gecode-users] AFC decay with global AFC in search 
> engines
>
> Hi Christian,
>
> Thanks for this. I decided to change my code to ude INT_VAR_AFC_* with 
> a decay argument, and then I tried to rerun the test. However, I now 
> get a Gecode exception "AFC: Illegal decay factor" for a factor of 0.0 
> with
>
> IntAFC afc(*solver, vars, 0.0);
>
> while previously, I was able to set the decay factor to 0 with 
> afc_decay(0.0).
>
> I assume this is because of a > vs >= test for the valid value. Should 
> this be changed? It seems 0 should be a legal value (even if it is not 
> too sensible).
>
> On a related note, from the description in the MPG, I assume there is 
> only a single AFC decay factor, so setting the decay factor with
>
> IntAFC afc(*solver, vars, decay)
>
> will also change the "global" decay factor, i.e. the one obtained by 
> afc_decay(). Is this correct?
>
> Cheers,
>
> Kish
>
>
>
> _______________________________________________
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> users at gecode.org
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>


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