Hello all,
we are currently trying to build a static checker system on top of
Gecode/J 2.1.1. (in an Eclipse environment), and we have found an
interesting case.
In order to allow us greater flexibility we try to use the Expression
API (it allows us to build constraints in a hierarchical manner).
I was testing the implementation, and found an interesting final
result: there were to IntVars, which were supposed to be the same, did
not have the same final ranges: one of them had {2,4}, but the other
had {2,3,4}. I tried to trace back the code to look whether the
constraints were wrong or not, and found the following expression
building term:
BExpr expression = new BExpr(new Expr(variable1),relation, new
Expr(variable2));
Tracing the variables variable1 was a new variable, it hadn't been
constrained yet, while variable2's domain had been limited to the
values 2 and 4 (and they were the variables mentioned before in this
letter), while the relation had the value IRT_EQ.
I tried a post of the expression right after it's construction to see
whether it helps or not:
org.gecode.Gecode.post(space, expression);
It did not solve the problem, but when I replaced the post method to
the following rel call, the constraint handling was working as I
expected it before.
rel(space, variable1, IntRelType.IRT_EQ, variable2);
I would like to know, whether this phenomenon is the intentional
(maybe I do not understand something under the hood), or not. And if
you could tell me a way to avoid it, I would be very glad.
Thank you very much in advance for your help,
Zoltán Ujhelyi
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