Topics started by amadeodum
Hello everyone, I am currently working on a Supply Chain problem (LS-U-B) and I am facing some issues that I can not solve. I have a standard formulation where the objective funtion is to minimize the total costs (Inventory and Backlog). The “classical” flow constraints are: Intenvory(s-1) + Production(s) + Backlog(s) =Demand(s) + Inventory(s) + Backlog(s-1) where s is the period (from 2 to 10). Production(s) + Backlog(s) = Demand(s) + Inventory(s) where s is the period (at time t=1) The standard model is running as it should without problem. However, I have to build an extended formulation for this constraint (strenghten the formulation) and it does not work. To do so, I created a new variable Production(s,r) representing the Production done at period s for the demand period r. Consequently, the following variables are: Inventory(s) = sum[r|ord(r)<=ord(s), sum[y|ord(y)>=ord(s)+1, Production(r,y)]] Backlog(s) = sum[r|ord(r)>=ord(s)+1, sum[y|ord(y)<=ord(s), Production(
Hello everyone, I face some issues to implement a constraint on AIMMS. Just to introduce you the problem: Y(o,l,t) is a binary variable which is equal to 1 if a liquid l (a beer) is ready in tank o at period t; Delta(l) is the fermentation time for a liquid l; How can I implement this constraint? Thank you for your help. Regards
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