[gecode-users] view selection combinator

[Martin Mann]

Hi Christian,

i didnt knew about the roadmap but it looks fine.
Have you already concrete plans for the tie-breaking combinator?

Additionally I would like to take into account more than one view to 
evaluate the view in focus. but for something like that i would have to 
write my own branching right? Seems to be more problemspecific than the 
tie-breaking..

Thanks,
Martin

Christian Schulte wrote:
> Looks good, indeed. If you check our plans for 2.0 you'll tie-breaking on
> our list:
> 	http://www.gecode.org/future.html
> 
> The hard part, however is how to specify in a model without hacking new
> branchings and not compromising efficiency.
> 
> Christian
> 
> --
> Christian Schulte, http://www.imit.kth.se/~schulte/ 
> 
> -----Original Message-----
> From: users-bounces at gecode.org [mailto:users-bounces at gecode.org] On Behalf
> Of Martin Mann
> Sent: Thursday, November 23, 2006 12:35 AM
> To: gecode user list
> Subject: [gecode-users] view selection combinator
> 
> 
> Hello,
> 
> I had the idea to write a hierarchical combinator VC (will be a 
> viewselector itself) for two ViewSelectors V1 and V2, that does the 
> following: for a view v it first asks V1 about v. if V1 says "better" v 
> is accepted (VC returns VSS_SELECT). if V1 says "equal" VC asks V2 about 
> v. if V2 says "better" v is accepted by VB else rejected or "equal" 
> returned.
> 
> The application is a free combination of existing view selections for 
> test reasons and to find the best view selection for my problem. I think 
> this is something other may be interested in too. For instance you ve 
> got a fast V1 for a first ordering and a more expensive V2 for a 
> detailed selection. a combinator would be great, because otherwise you 
> ve got to apply the expensive V2 always to all views.
> 
> Now comes my problem: the possible return values of ViewSelectors:
> 
> enum  	Gecode::ViewSelStatus {
>     Gecode::VSS_NONE,   // not better
>     Gecode::VSS_SELECT, // is better
>     Gecode::VSS_COMMIT  // is the best ever
> }
> 
> i ve got no possibility to get or return the information "is as good as 
> last best seen". as far as i can see it wont be a big deal to introduce 
> this into the enum and the existing standard viewselectors if you think 
> that it is worthy. e.g. as second a VSS_ALIKE. by that you wont change 
> your interface and no changes in the branchings are neccessary. I can send
> you the template code of the combinator when its done if you 
> like the idea.. ;)
> 
> maybe the "alike" information can be usefull somewhere else too. but 
> right now i ve got no further good idea.
> 
> thanks for interest,
> 
> martin
> 
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