Hi,

I appreciate very much if you help me resolve the error in the following simple example. Here are the mod and dat files:

// mod file

using CP;

tuple Task {

  key int id;

  int   duration;

  {int} FSSuccs;

  {int} FSLags;  

}

{Task} Tasks = ...;

dvar interval task[t in Tasks] size t.duration;

minimize   max(tt in Tasks) endOf(task[tt]);

subject to {

                            //Gives error "Not an Array" on the Lag t1.FSLags[<t2>] 

                            //but works if I put any constant value, like 0 or any other value

  forall (t1 in Tasks, t2 in t1.FSSuccs) endBeforeStart(task[t1], task[<t2>], t1.FSLags[<t2>]);  

}

execute {

 }

//.dat File

Tasks = {

  < 1, 8, {6},{6}>,

  < 2, 8, {5,3,4},{2,0,3}>,

  < 3, 7, {5},{0} >,

  < 4, 4, {5,6},{0,0} >,

  < 5, 9, {8},{8} >,

  < 6, 6, {},{}>,

  < 7, 12, {},{} >,

  < 8, 4, {},{} >,

 };

------------------------------
Tarek Hegazy
------------------------------

Hi Tarek,

t1.FSLags is a set, not an array. It is however considered as an ordered set where elements can be accessed by their index.

For instance, one could write your constraint as follows:

endBeforeStart(task[t1], task[<t2>], item(t1.FSLags, 0));

I hope this can help you.

Best regards,

Hugues

PS: I suppose a better formulation would be: item(t1.FSLags, t2). However, I'm not sure to understand the values for FSSucc in your data. The later formulation will result in errors if executed with your data.

------------------------------
Hugues Juille
------------------------------

Fantastic. It worked. Very much appreciated. You are a life saver. Thank you.

Tarek

------------------------------
Tarek Hegazy
------------------------------

Original Message:
Sent: Fri February 24, 2023 08:24 AM
From: Hugues Juille
Subject: Urgent Help Needed

Hi Tarek,

t1.FSLags is a set, not an array. It is however considered as an ordered set where elements can be accessed by their index.

For instance, one could write your constraint as follows:

endBeforeStart(task[t1], task[<t2>], item(t1.FSLags, 0));

I hope this can help you.

Best regards,

Hugues

PS: I suppose a better formulation would be: item(t1.FSLags, t2). However, I'm not sure to understand the values for FSSucc in your data. The later formulation will result in errors if executed with your data.

------------------------------
Hugues Juille
------------------------------

Hi,

  item(t1.FSLags, t2) is the correct thing to use. Without it the answers are wrong. Is there any other way to get the proper index to t2?

Thanks in advance.

------------------------------
Tarek Hegazy
------------------------------

Original Message:
Sent: Fri February 24, 2023 08:24 AM
From: Hugues Juille
Subject: Urgent Help Needed

Hi Tarek,

t1.FSLags is a set, not an array. It is however considered as an ordered set where elements can be accessed by their index.

For instance, one could write your constraint as follows:

endBeforeStart(task[t1], task[<t2>], item(t1.FSLags, 0));

I hope this can help you.

Best regards,

Hugues

PS: I suppose a better formulation would be: item(t1.FSLags, t2). However, I'm not sure to understand the values for FSSucc in your data. The later formulation will result in errors if executed with your data.

------------------------------
Hugues Juille
------------------------------