If you have start and end time for each activity then you could add a constraint for each precedence relationship. E.g. StartTime(B) >= EndTime(A). Could it work?

Hi @Melike I wonder, did that help you? Or did you find another way?

Hello, i found another way to make it because i wanted to avoid giving start times and end times.

But it was not really as good as i wanted because i wanted to use the restrictionns afterwards to make the precedence relations so that it is globally used in my model

Thanks  alot anyway

Hello @Melike, seems you considered using Constraint Programming for this. Are you aware that @Chris Kuip did a few webinars on this? One that has a scheduling app example can be found at the link below and could be helpful for you.

https://www.aimms.com/english/developers/resources/webinars/webinars-demand/modeling/aimms-training-webinar/

Hello @Gertjan no i didnt know.Thanks a lot for the advice. I will take a look.