Custom constraint OR-Tools // Constraint programming

Question

I am working on a geometry problem with the OR-Tools constraint programming tools.

Could one of you tell me the procedure to create a custom constraint? I dont really understand demon, model visitor behavior...

Also, can any type of constraint be inserted?

Thank you in advance

Please elaborate your question: What kind of constraint do you want to add? What have you tried, and what feedback did you get? — Peter Smit
– Peter Smit, Commented Jan 8, 2018 at 8:37
I use Or-tools to generate polygons under certain constraints. I would like to know if it is possible to create custom constraints using functions of other libraries (I think especially in my case Boost and more particularly Boost geometry). Considering (Xi, Yi) the coordinates of the points of a polygon. I would like to create a constraint of this type: void AreaConstraint (Solver * solver, IntVar * X1, IntVar * Y1, IntVar * X2, IntVar * Y2, IntVar * X3, IntVar * Y3, IntVar * X4, IntVar * Y4, IntVar * X5, IntVar * Y5, IntVar * X6 , IntVar * Y6) — Ella
– Ella, Commented Jan 8, 2018 at 8:40
int64 x [] = {X1 -> Value (), X2 -> Value (), X3 -> Value (), X4 -> Value (), X5 -> Value (), X6 -> Value ()}; int64 y [] = {Y1 -> Value (), Y2 -> Value (), Y3 -> Value (), Y4 -> Value (), Y5 -> Value (), Y6 -> Value ()}; -> there I have a problem, I obviously do not have the "right" to access Xi -> Value (). — Ella
– Ella, Commented Jan 8, 2018 at 8:41
I tried to create a class in the same style as : class AllDifferentExcept : public Constraint { ....} — Ella
– Ella, Commented Jan 8, 2018 at 8:50

Laurent Perron · Accepted Answer · 2019-03-23 10:51:13Z

2

To write a constraint, you need to understand that during search, variables are not instantiated (domain is reduced to a single value). Therefore, calling Value() does not work.

You can access the current domain (min, max, list of possible values, and then you can write deduction rule from there).

See https://github.com/google/or-tools/blob/stable/examples/cpp/dobble_ls.cc.

Now, the CP solver is replaced by the CP-SAT solver, which does not allow writing custom constraints. In that case, maybe you can express you constraints with boolean logic, and arithmetic operators.

answered Mar 23, 2019 at 10:51

Laurent Perron

11.2k1 gold badge10 silver badges27 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Custom constraint OR-Tools // Constraint programming

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related