[gecode-users] posting of expressions

[Kish Shen]

Hi,

As I have mentioned in my previous posts, I have been rewriting the code 
for handling expressions for the ECLiPSe interface to Gecode. I am 
wondering if there are any performance advantages in different ways of 
handling certain special cases of expressions, like sum.

I had some special code that handled summation of variables using linear:

linear(*solver, vars, rel, sum)

where vars in IntVarArgs, sum is int (although I guess it could be 
generalised to IntVar as well), and rel is IntRelType.

This code does not seem to be used at the moment, I assumed I had it to 
handle some specific ECLiPSe code that I wanted to run quickly with the 
interface.

Instead, such summed expressions are now handled through the general 
expression handling code, and passed to Gecode as a LinRel through 
minimodel. The sum is passed as a series of +, e.g. A+B+C rather than 
using sum of a IntVarArg, because the code was written for Gecode 3.0.2, 
which I don't think supported sum.

Is it more efficient to use the more specialised linear to post such 
expressions, and is it more efficient to use sum in LinExpr rahter than 
a series of +?

Thanks in advance for any information!

Cheers,

Kish

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