Optimization Tooling

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, 

Hi,I took the exampleNFL project from the documentation and was trying to modify the input data, write it to excel sheet Output.xlsx, cross check if the data is being modified and download the same. It seems to work till cross check part but I am facing difficulty with downloading. Could you please let me know where am I going wrong with the model? I have attached the model for your reference. Also, the model needs to work on Cloud.Thanks,Vishwesh 

I save the post on how to solve multiple instances of a model iteratively. However, the question I have is how can it be done when using AIMMS Pro? Right now the problem is all instances are being sent out to the cloud at the same time. I want to run one instance, and then the other after that, and based on its results. Can something like this be done? 

Hello,we are in the process of updating many of our web applications to use Google Analytics. This involves adding a small script to the main page (ex. index.html) in the <header> section of the html.Has anyone else done this and are there any known issues with doing so?  I know if you try to manually edit the configuration file it gets overwritten when you restart the services via configurator, so not sure if there is a similar protection on the HTML files . Or, alternatively, has anyone set up app Azure/Application Insights with AIMMS Pro?

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.   

Has anyone solved how WebUI shows default inf values? It is crashing my system over, and over again. Page Name@contents: Identifier 'Parameter' contains special value 'inf' which is not supported (and displayed as 'Infinity')

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.

One customer recently shared with us a success in reducing a long solve time by 80% with the new functions CreateBlockMatrices and SendToModelSelection available as of version 4.81.1 Could this method help your model solve faster? See details about the case below. We were facing issues with the solve time of this model, especially given the exponential growth of solve time when we solved larger models. Back in January, we started to investigate the cause of the long solve time together with AIMMS. However, the start of this investigation was daunting: no matter what we tried in model reformulation, scaling, different solvers or solver settings, the performance did not significantly improve.  We concluded that if all else failed, we could always solve the individual time periods in the model one-by-one (because in fact those time periods are not connected). To efficiently split the generated matrix in smaller independent submatrices, solve them one-by-one, and merge back into one soluti

Hi, I have a problem with the callback procedure that is called at each iteration but  not the last. At each iteration, the callback is  called, if the solution violates the constraints, the cuts are generated and added to the model, but in the last iteration the callback is not  called at all, so the feasibility is not checked and the optimal solution provided by (cplex or gurobi, I tried both) is  in fact infeasible.  This  is  a scheme of  the  code: GMPRelaxedModel := GMP::Instance::Generate(NoEnergy_per_lazy) ;GMP::Instance::SetCallbackAddLazyConstraint( GMPRelaxedModel, 'Robust_NogoodCut' );GMP::Instance::Solve( GMPRelaxedModel );

XML vs JSON : When discussing both XML and JSON APIs, we must emphasize that both have the same objective, in specific terms it can be said that both are accomplish the same goal. The motive of their uses clarifies the best method for them. Extensible Markup Language or XML is founded hard to learn while JSON or JavaScript Object Notation is very easy to learn. XML is not that much convenient with API or Application Programming Interface in comparison with JSON .  

Dear Users, I have designed a MINLP problem and using AOA as solver. The reason I have to use AOA is my problem has goniometric functions and therefore BARON cannot be used. Also, I am using educational license which restrict KNITRO to solve problem over a specific size. When I solve problem using AOA such that it has initial solution (from a small solved network by knitro or AOA), I get final optimal solution in few seconds by AOA. For example, I solve a 4 node network using KNITRO and use this solution to solve 5 node network by AOA and in this way I gradually increase network size and keep getting result by AOA using solution from previous smaller network. This works fine. But, if I want to solve a network with no initial solution, either I get “infeasible solution” (although it has feasible solution in real) or solution time becomes so high and non-stopping (in hours). I have tried setting a bigger value of relative MIP optimality tolerance and MultiStart and increasing the Maximum

Dear All, I have been trying to use ellipsoid uncertainty in a simple problem that I have.The problem is an assortment optimization. Then, I have the Demand Mean for each products Dem(p) and the Covariance matrix or the variance Var(p,p1) for each par of products. The objective is to select the products what will maximize the expected demand Dem(p) at the same time, penalizes products with high variance. The uncertainty set will be a ellipsoid uncertainty. I would like to create the eelipsoid uncertainty using the uncertainty region like:Demand(p).level - sum[p1 , Var(p,p1) * …………There is a example in the book on page 341. but it’s not clear for me.  Could you help me to model the ellipsoid uncertainty using the uncertainty property? Thank you 

Dear Community, As explained in the previous article New WebUI Widget Framework - Part 2, we  are working on a new and more robust WebUI Widget framework. While we are at it, we are also  building new Column Chart and Line Chart widgets. We look forward to having these 2 widgets available as a Beta release towards end of this year. We will offer a demo of these features  in our upcoming `Online User Meetup | Live WebUI Product Update`. Please register here. We have also  improved our Widgets Option Editor. This has resulted in better performance  and new features such as:Categorizing index related options (Like Store-Focus, Totals, etc.) Default identifier options Options inheritanceFor example, on the Column Chart, we can now set defaults for generic options like Display Units and Num Decimals, and then inherit these default values upon each of the data identifiers. You can overwrite these inherited options by setting an explicit value.Column Chart The new Column Chart and Line Chart

Hi fellow AIMMS users.I need help on formulation of piecewise linear functions. I have read section 7.6 of the AIMMS modeling and applied the concept to the Piecewise Linear transportation example. However, I find it difficult to apply it to my case.This is my case: I have also attached the developed model. When I ran the model, error that popped up is“Outer Approximation cannot handle columns like 'Lambda(Gen1,1)' that are continuous and member of a SOS set” Please, I need assistance on how to go about this. Thanks

Hello everyone,I am trying to implement a supply and demand model in AIMMS. This is the first time using it for me and I'm having some issues. The case is as follows: There are Printer companies that supply books to Retailers. These Printers can send the books directly to retailers, or through crossdocks to be consolidated. I have modelled the set of Printers with index P, the set of Crossdocks with index C and the set of retailers with index R. The case asks for a set of locations as the union of these three sets L = P ∪  C ∪ R. I am not sure how to model this union of sets and can't seem to find any info on this. Does anyone know how to do this?Not sure if it matters, but the amount of Printers, Crossdocks and Retailers should be variable and dependent on an Excel input file. Thanks!

 I want to express “State_CHP=0 when Input_energy(t,conv)=0” and “State_CHP=1 when Input_energy(t,conv)>0”, but there always some errors. I have checked the help manual, but there is no specific example of how to explain it.Thank you very much. You will be of great help to me. Thanks.

Hello,I’m trying to run an application via AIMMS Pro/WebUI. I can run the optimization via AIMMS Developer/WebUI without a problem, but when I try the same on the AIMMS Pro server the following error-message appears: awf.data.aimms.session: Running procedure 'testprocess' has resulted in an error: API Error 0 when running procedure 'testprocess': (code=500) Can anyone help me with that? Best regards Jonathan

We have a winui based Pro app hosted on a server with updated licenses and adequate maximum number of users.                                                                                                                                      However, some of the users seem to have received the following error when they open the aimms pro app. I have noticed this error only with developer licenses in general. Could you advice on a possible cause so we could investigate further? 

I am a new student. After clicking ‘’main execution‘’ button, the progress window is as the first picture, which don’t enough information, such as  the second picture. At the same time, the messages window is like the third picture, having ‘.’ in the window. My code is given from my senior, she can get the right answer in her aimms that is a elder version. However ,in my aimms4.76 I can’t get the answer.

spreadsheet::CreateWorkbook(results/Exercise_7/results_demands.xlsx,Energy_demands) failed: Could not open Excel.  why 

As the title of this question indicates, I am looking to work in developer, but send the solve statement to a pro solver session. (And retrieve the results of course)Two main reasons for this are:In that way my laptop will not be taxed (and overwhelmed) by the models that I am developing In this developing stage I gather date from a database that is not connected to our PRO environmentA workaround that does work is to publish the app including relevant data (as a case to the app). However this is a rather inflexible way of developing. As an extra detail, at this point in time my machine cannot generate and solve the instance in reasonable time, while my described workaround takes a little under 2 minutes.

Dear Community, I hope everyone is well.I'm studying some forecast functions inside AIMMS and would like to know if there is a function to create the forecast using ARIMA, SARIMA or similar method, Thank you