[gecode-users] view selection combinator

[Martin Mann]

;) Ok Greg,

now we are two! ;)
Tie-breaking sounds great, but anyway it wont function without the 
"alike" support of the ViewSelStatus..

Martin

Grégoire Dooms wrote:
> Great, I need this.
> I would call V2 a tie-breaking strategy for V1.
> Best,
> -- 
> Greg.
> 
> Martin Mann wrote:
>> 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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