Hi, Gecode doesn’t do a lot of preprocessing of the model. In particular, it doesn’t do any aliasing analysis or common subexpression elimination. You could try a modelling language like MiniZinc, or implement your own preprocessing, if you need this stronger behaviour.
Cheers, Guido -- Guido Tack http://www.csse.monash.edu/~guidot/ > On 22 Sep 2015, at 7:49 am, Neill Clift <neillcl...@live.com> wrote: > > Hi, > I am having a blast with Gecode! I have this small system to demonstrate > something I want to improve in my code: > > e[0] == v[0] > e[2] == v[1] > e[4] == v[2] > v[0] >= 1 > v[1] + v[0] >= 2 > v[2] + v[1] >= 1 > v[2] >= 1 > v[0] + v[1] + v[2] == 5 > e[4] + e[2] + e[0] == b[0] > e[5] + e[2] + e[0] == b[3] > > This gives me: > b{[2..5], [1..5], [1..5], [1..5], [0..5], [0..5]} v{[1..4], [0..3], [1..4]} > > So the code doesn't see that > e[4] + e[2] + e[0] == b[0] > e[0] == v[0] > e[2] == v[1] > e[4] == v[2] > v[0] + v[1] + v[2] == 5 > > means that b[0] == 5. > > A more complicated case is b[3] must be >= 2. > Is the level of indirection (v -> e -> b) the problem or recognizing an > inequality is common to two expressions? I am guessing it's the second case. > Is there a way to do this differently to get the better result? > Thanks. > Neill. > > _______________________________________________ > Gecode users mailing list > users@gecode.org > https://www.gecode.org/mailman/listinfo/gecode-users
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