AIMMS Language

Hello All!I wanted to start a thread in the community to discuss implementations and solutions to the Kaggle X-Mas challenge. For those of you who don’t know, Kaggle it is a site intended for promoting data science through courses and challenges. Every X-Mas they have a special optimization challenge. You can find more information below on this years challenge in the link below:https://www.kaggle.com/c/santa-2021/overviewA quick summary is: “Santa is creating a new streaming service and will play a 24/7 loop of 7 films. He would like the showing sequence to be optimal. Hence 3 groups of elves are watching all possible sequences (7! = 5040) of 7 movies to evaluate what is the best sequence.So, it has to do with permutations and TSP’s. Permutations, because we need to identify all possible combinations of sequences. And TSP’s because the problem can be transformed to a multi Traval Salesman Problem. Every salesman in this case is a group of Elves, and every city is a sequence of (7) film

I have downloaded the example model of VRP and going through it.I was not completely able to interpret the Subset code.I have few questions as specified belowwhat the while loop is doing.Below code how  please help me understand    CurrentSubset(CurrentPosition) := 1;    CurrentSubset(c | CurrentPosition < c) := 0;Finally in the if statement  line     SubsetIndicator(comb, c) := CurrentSubset(c);

I need to fill the 6*6 matrix as shown in the above.Here (i,j) is from 0 to 6So I used below code to achieve the matrix as shown above Here my question is I am trying to achieve this constraint x(i,j)=1 if either i or j =0 or 6Is there a better way to use Index domain to achieve that

Above is my sudoku result how to fill the above result into one single matrix with all values..Any feedback please

how to model the specified constraint in AIMMS any feedback please. I tried like 3*i+a . it is not accepting multiplication and addition of indices 

In AIMMS it is possible to define a set via a union of some of its subsets. As an example: Set Locations {     Definition: Factories + Warehouses + Stores;}Set Factories {    SubsetOf : Locations;}Set Warehouses {    SubsetOf : Locations;}Set Stores {   SubsetOf Locations;} This is a powerful feature in AIMMS and it seems very logical to use, but to implement this, we are faced with several exceptions to the normal flow.Because:For an ordinary subset it is not allowed to add elements to it that are not present in the super set. But if AIMMS would not allow that in the given example, then it becomes impossible to fill any of the sets with elements. So, if AIMMS recognizes this construction it introduces an exception that is should allow that the subset (temporarily) contains elements that are not in the superset. Only after the definition of Locations has been re-evaluated the expected subset relation is corrected. AIMMS works with dependencies between identifiers. When assigning to an

This webinar is from 2014 and contains a lot of (still current) information about how to investigate the cause of Infeasibility in AIMMS. Webinar - Analyzing infeasible Problems in AIMMS

Dear All,I'm designing an optimization model to determine the power generation capacity from local energy sources. If the local energy sources are not sufficient, the need for electrical energy that cannot be met from local energy sources is met by importing electrical energy from other regions.I'm currently using an imported electrical energy variable (Imp_Electricity) in the energy balance constraint function. However, after using the price of imported electrical energy, the optimization results show that all electrical energy needs are met by imported electrical energy and no generating capacity is required. This is because importing electrical energy is cheaper than having to build a power plant. And when the Imp_Electricity variable is assigned a value of ZERO, the model is not feasible because the energy balance constraint function is violated.The result I expect from the model that I am currently designing is that the model can prioritize the construction of power plants to dete

Hello! I am facing an issue with my model. I have a variableA(index1,index2,index3,index4)and I am defining another variableB(index2,index3,index4) as max(index1, A(index1,index2,index3,index4))However, while running the model, it gives an error that the the model become non linear. Is there a way to work around this? Regards,Vishwesh Patil

Using WinUI, The user can select the time granularity in the model (4,8,12,24 hours). Everything works, except the Gannt chart in which the “X-axis ->Unit of Measurement” cannot be a reference to a parameter. Is there a way to solve this issue so the Gantt chart can also be responsive to different time granularities?  Thanks

Dear All, I want to generate an integer parameter based on the combination of a number of component as shown as:   K1 K2 K3 C1 1 1 1 C2 1 1 0 C3 1 0 1 C4 1 0 0 C5 0 1 1 C6 0 1 0 C7 0 0 1 C8 0 0 0   where K1 … Kn is the number of component and C1 .. Cn is generated combination based on component number. The value of 1 means that the component is available and the value of 0 is otherwise. Is it possible to do this in AIMMS? Thank you very much.

Dear community, I am implementing a structure change in my database declaration and keep coming across the error below. It occurs when mapping database columns to variables, using the DatabaseTable function. The change I have made is in adding an index "st”, and the column names in the data source Access Database.The error:The index "uc" present in Ramp_rate(uc, yr, ct) is not present in the previously generated entry (WorkingH2(i, yr, st)) of this read statement.  AIMMS generates communication links when they are not explicitly specified between the keywords read/write and from/to.  These entries are constructed by considering the column names in the database, the identifier names in the model and/or the database table mapping attribute.The variable Ramp_rate has little connection to the read statement where the error occurs. Has anyone encountered this error before, and do you have an idea what problem this error most likely hints towards? Thank you kindly for your help in advance,Sa

These cannot be saved, but I am still asked the question if I want to save the layout (followed by an error that it cannot be saved).

Hello everybody,I have a problem with around 3000 suppliers, each supplier is independent. Our Aimms runs in a loop solving a MIP model for each supplier with around 800 variables and a gap of 2%. Each model runs very quickly at around 5-6 seconds, but the entire run of 3000 suppliers takes around 30-40 min. We need to improve the time of the model and I would like some sugestions. Options we are already thinking:a)  Merge the models in batchs of suppliers, creating a bigger model and pass it to the solver.b) Performance tunning of the CPLEX optionsIs there any other suggestion? Is there some way to run the models in parallel for example? 

 Dear AIMMS experts, it would be great if there is a working example related to calling AIMMS from python using the latest release REST API.Also,  following on other recent python-AIMMS questions here, could you kindly clarify the following questions:is the method of calling AIMMS using 'win32com' in python still valid? (as seen in the office github repo example in 'examples/Functional Examples/Calling AIMMSCOM/RunAIMMS.py ' ? is the previous method of calling python using 'subprocess' module and command line still valid for the recent version of AIMMS ? does the ways of calling AIMMS in python subject to the type of license I have (I have both free and paid academic licenses) ?

 Good morning all,Please, can someone tell me why I keep getting this error ? Both SOC(agg,t) and P_Charging(agg,t) are variables.Thanks so much.  

Hi, I seem to have difficulties with defining the number of decimals when rounding my parameters . The function description tells me I should define a positive integer for defining the number of decimals on the right of the decimal point, but this function gives me a different number of decimals. I use Units of Measurement and I think the ‘internal’ unit is rounded instead of my defined unit for the specific parameter (which differs in order 6 (10^6) ). Do more people encounter this problem?

Hi, I want to interrupt a procedure with an if condition. For example:if (a condition) then   TestProcedure1;else   *interrupt current procedure;endif; I know I can use BREAK; to stop the loops. But how can I stop a procedure?

@Gertjan @MarcelRoelofs I’m wondering: is the DataExchange library the recommended way to read Excel files from now on, for new apps? I think I understood that from earlier conversations and also the replies above, but I’m hesitating since the AXLL library is mentioned as a best practice here: https://how-to.aimms.com/Articles/85/85-using-axll-library.html. 

Dear staff,I would like to receive your help with linearizing the following constraint. Given the indexes i, j, c, a I have the following variables and parameters: x (i,j,a) continuous variabley (i,j,a) continuous variableR (i,j,c,a) binary variableA (i,j) parameterB (c) parameter The constraint that I need to write is the following: y(i,j,a) = (x(i,j,a) / A(i,j)) * (1 - sum((c,a1)|ord(a1) <= ord(a), R(i,j,c,a1))) + sum((c,a1)|ord(a1) <= ord(a), (x(i,j,a) / B(c)) * R(i,j,c,a1)) forall i, j, a I am struggling in particular with the linearization of the second part:sum((c,a1)|ord(a1) <= ord(a), (x(i,j,a) / B(c)) * R(i,j,c,a1)) Please note that there are already other constraints imposing that sum((c,a), R(i,j,c,a)) <= 1 forall i, j, therefore the summation of sum((c,a1)|ord(a1) <= ord(a), R(i,j,c,a1)) is always either 0 or 1. Thank you,Kind regards, 

I need to impose a time limit for AOA and  after the time limit  is reached,  the value of  the incumbent is returned.MPOuterApprox::TimeLimit :=500;GMPOuterApprox::IsConvex := 1;GMPOuterApprox::DoOuterApproximation( GMPRO );BestAOA     := GMP::Instance::GetObjective( GMPRO ) ;ProgAOA := GMP::Solution::GetProgramStatus( GMPRO, 1 );display BestAOA , ProgAOA; GMP::Instance::Delete( GMPRO ); in the progress window I can see a  value to the “best solution” is assigned and  the gap is around 30% but when the time limit is reached, the values assigned to BestAOA , and   ProgAOA are as follows:     bestAOA := na ;    progAOA := 'IntermediateInfeasible' ;I appreciate any help in advance.  

There is a solver Solving Constraint Integer Programs (SCIP). https://scipopt.org/doc/html/index.php#WHATISSCIP How to connect it to AIMMS?I’m trying to add libscip.dll via Solver Configuration, but recieve an error.   

When AIMMS is solving on my machine, it consistently uses a little over 21% of the total CPU capacity. Is it possible to let AIMMS use more than this?EDIT: After investigating a little more, the ‘problem’ occurs while AIMMS is building the model. CPU usage during the solve is harder to observe since it is quite quick. The CPLEX 20.1.sta file shows that it prepares to use up to 8 threads.