[gecode-users] Arc consistency, value and variable ordering

[Claudio Cesar de Sá]

Hi,

In arc consistency algorithms, such the AC3 and its derivatives,  you need
do two choices:

1: Which is order of these variables are to be considered?
2. Which is the order of their  values are assigned to the variable?

These two parameters are in branch method, section 9.1., figure 9.1 ...
I am with some doubts on their meanings, such:
[INT\_VAR\_REGRET\_MIN\_MIN:]     With smallest min-regret.
The min-regret of a variable is the difference between the smallest and
second-smallest value still in the domain.

For example: considering  variables X and Y ... Dom(X)={2, 5, 8, 11}    and
Dom(Y)={1, 6, 18,  20}  .... X should be chosen
once |2 - 5|  has a small  regret ... comparing with |1 - 6| of Y ?

Other question, the parameter  INT\_VAR\_SIZE\_AFC\_MIN,  should the
well-known as *first-fail*?

Or INT\_VAR\_NONE,  first unassigned, should be the first variable found in
the list of pair (variable, constraint) considered
in arcs consistency algorithms?

Where can I find details of these parameters accept by the Gecode? In int.hh
are their specification






-- 
claudio



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