Parameter already define and sets that needs to be subscripted.

[Emanuele De Villa Bais]

I'm using AMPL as a student, so usually I handle simple problems.

These days I'm facing something harder and I have a lot of problem with it.

In particular AMPL says that parameters from "consumo_turn" to the end are already defined and that sets SPEED and ALT need to be subscripted. I read some posts on this group and I tried to implement some correction, but without results. Can you help me?

Thanks in advance,

Emanuele

[victor.z...@gmail.com]

Since SPEED and ALT are collections of sets indexed over AEREI, you need to use subscripts to access individual sets:

  param consumo{a in AEREI, z in ALT[a], v in SPEED[a]} >= 0;

Same in other places where ALT and SPEED are used.

See Section 6.5 Indexed collections of sets of the AMPL book for more details.

HTH,

Victor

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[Emanuele De Villa Bais]

Thank you!

I made it right into constraints declaration but I missed that one!

Now I have another problem, I got a syntax error on constraints "separazione1" and "separazione2", I think because I need 4 restrictions on these constraints and I don't know the correct syntax to write that.

Could you please give those a look?

[victor.z...@gmail.com]

The colon followed by the logical "such that" expression should be at the end of the indexing expression and you can combine multiple conditions using the and (&&) operator:

  subject to separazione1{a in AEREI, b in AEREI, t in TIME, z in ALT[a] inter ALT[b]: b <> a && t >= max(start[a],start[b])} :

Same for other constraints.

See section A.3 Indexing expressions and subscripts of the AMPL book for more details on the syntax of indexing expressions.

HTH,

Victor