[gecode-users] Why do we need to update variables for propagators

[Zhu Zichen's cse]

Dear Christian,

Thanks very much for your replying. I did some experiment on the
BIBD(7,3,7) benchmark. I checked the profile after utilizing the two
versions: one-for-each, GLOBAL_ONE. The calls of the update function cost
60.81 and 8.50 seconds by one-for-each and GLOBAL_ONE respectively. While
the propagate function totally costs 5.73 and 7.64 seconds respectively.
Even though GLOBAL_ONE is slower when doing filtering, it wins for the less
calls of update function.

A variable is really only a pointer to a variable implementation which is
copied at most once.
You mean no matter how many update calls of a variable during a copying, it
would be copied at most once? If so, why would we need to update these
variables in a copy function of propagators as we have done it in the Space
copy function?

Yours,
Zoe
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