[gecode-users] doing multiple minimising searches with the same space

[Kish Shen]

Hi,

I am now trying to add support for the minimising search engines (BAB, 
Restart) to the ECLiPSe-Gecode interface I am developing.

I think I can see how to implement the cost function, which is only 
given at run-time (with the limitation that the cost is a finite domain 
variable, which has must have a vlaue assigned at the end of labelling 
all the variables specified in the search), *if* the search is done only 
once:

In the Space class I use, I have a IntVarArray (called vInt), 
representing the problem variables. To implement the cost variable, I 
add a Cost IntVar to the space, and when the search routine is called, I 
post an additional constraint

Cost = vInt[i]

where vInt[i] is the problem variable that is defined to be the cost 
variable.

The constrain/cost member function required can then perform the right 
action using the Cost variable.

However, at the ECLiPSe level, I can perform more than one minimising 
search while solving a problem, with different cost variables (and 
persumably with a different set of problem variables). I am not sure how 
I can do this with what I know of Gecode's search engine interface, as I 
have already posted a constraint linking Cost to the vInt[i], cost 
vafriable for the previous search.

Thanks in advance for any help/suggestion for how I can program this!

Cheers,

Kish

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