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 The binds-existing attribute can be used in conjunction with the binds-to attribute to indicate that, when reading a data file, no new set elements will be created, allowing for a filtering mechanism where a data file can only be partially read for the nodes that correspond to existing set elements in the model.I have a predefined set named t with valued {1,2,3,4}.I want to read an Excel file which contains a column named “time” having values (e.g., 0, 5, 6) not included in the previous set, which I do not want to add to set t.I am specifying the binds-existing attribute in the DEX mapping as follows:<ColumnMapping name=”time" binds-existing="t" binds-to="t" />I have not changed the skip-non-existing attribute, so I was expecting that binds-existing attribute would not add the referred values (0, 5, 6) into the predefined set t. However, it still does.What am I doing wrong? Did I correctly specify the binds-existing attribute?Thank you very much PS: There are almost no specific

Model descriptionWe have a non-linear mathematical model with the following set, variables, and parameters: Set t in [1,N_T]     Variables x_t y   Parameters A B C_t  And the following objective function:min{sum((x_t-A)/A) for all t}Subject to:x_t = x_{t-1} + B(Ay - x_{t-1}y - C_{t-1})x_t >= 01<= y <= 2499999With the initial value of the variable x_t being:x_1 = 19,500The values of the set are:t = [1 2 3 4 5 6 7 8 9 10]The values of the parameters are:A = 21,500B = 0.00095C_t = [50,000 50,240 50,300 51,000 51,040 50,700 50,800 50,200 49,000 48,700]SolvingThe non-linearity in the problem lies in the following product in the constraint:x_{t-1}yWe have implemented the model in AIMMS and tried the Outer Approximation algorithm for this problem, but get the following error message:The generated mathematical program “OA_NLP” has type “QCP” which cannot be changed into “RMINLP”.What might be causing this message? Also, does anyone have suggesti

Given the example of the data I would like to bind each sales volume to a period and sales channel to fill the following parameters . P_MinVolumeSalesChannel(i_Product,i_DemandTerminal,i_Period,iSalesChannel). P_MaxVolumeSalesChannel(i_Product,i_DemandTerminal,i_Period,iSalesChannel).  I know that I could use name-binds-to =”i_Period” and the name-regex-prefix, but could I use name-binds-to again for “i_SalesChannel”?

I want to map data from an Excel file using DEX ExcelSheetMapping to a parameter named “Capacity”.However, I cannot get that null (“0”) values are read into the parameter “Capacity”.I have a constraint that imposes an upper limit over a variable named Stock, as follows:Stock <= CapacityI need to read null (“0”) values to impose that the variable Stock is null.How can I do it?Thank you PS: I omit indexes for the sake of simplicity

Hi, when I solve an optimization problem (which is convex), though there should be only one optimum solution theoretically, I can get nearly the same objective value but totally different decision variables under different solvers and even within the same solver under multi run.Now I want to reduce the precision on the variables. Currently the continuous variables may search into 20 digits after the decimal point, how can I limit it into maybe the first two digits after the decimal point? Can AIMMS do this?Thanks a lot.

Hello guys! I have a bit of a problem, I am working in a model that includes Gross Cash Flows (in the model defined as Variables, V_GrossCashFlow), which can be positive or negative of course. If the Gross Cash Flows are positive, then a Tax Rate should be applied to them, resulting in Net Cash Flows (V_NetCashFlow). If the Gross Cash Flows are negative, then Net Cash Flow will just be equal to the Gross Cash Flow. For the V_Net Cash Flow variable I am using a definition such as the following:if (V_GrossCashFlow(tr) > 0 [€]) then    V_GrossCashFlow(tr) * (1 - P_TaxationRate)else    V_GrossCashFlow(tr)endif;The obvious problem with this is that the model goes from being LP to NLP. I was wondering if you guys had any idea to model this situation without introducing Non-Linearity. I have tried using binary variables a bit, but every solution I can find with them forces me to define the binary variable using V_GrossCashFlow anyway, so the model is still Non-Linear.I would be very thankf

Hi all, I am going to run the AIMMS with many different scenarios(case data) automatically. In case the solver may not find the optimum solution in some of the scenarios, I wonder is there any parameter or index (such as 0 or 1) I can get after solving each case to indicate if the solver has got the optimum solution?

The reason for my question is that mapping with DEX package for CSV is limited by the number of dimensions possible in a single file and therefore needs the use of multi-level columns.  This limitation requires me to use multiple CSV files for my problem. While using the bind-to and maps-to mapping elements are useful with single line headers and can even be extended with help of .regex, I was wondering if multi-line headers could be adapted to the data exchange mapping elements for csv. Showing a sample table below with the problem that I am facing.    Set4_val1 Set4_val1 Set4_val2 Set4_val2 Set1 Set2 Set5_val1_Set_4_val1 Set5_val2_Set_4_val1 Set5_val1_Set_4_val2 Set5_val2_Set_4_val2 a aa 5 6 7 8 a bb 9 10 11 12 b aa 13 14 15 16 b bb 17 18 19 20 The final value in the table, lets called the parameter X is such that X(set1, set2, set4, set5)Thank youWith Best Regards - Prem 

First, let me introduce myself (as its my first post):Im and Industrial Engineer student making my end of master project studying the scheduling of a production plant. My tutor recommended me AIMMS to solve the MIP scheduling problem and, as you might have guessed none of us used this tool ever So far so good, i have found a scientific paper that solves my particular problem ( i dont think i can upload the paper, so I’ll upload only the good stuff)If AIMMS has a good thing its that it was easy (even for me) to introduce most of the constraints and definitions. So i made (most) of themBut theres one that particularly bothers me, restriction (2) and in a lesser way (7). This ones check the inventory stock at the the end of a certain T time, but if T=0, then it check It-1 (which it doesnt exist). And if T=1, it check It=0The thing is that I created a Parameter that holds the Initial Inventory and i wanted to keep as close as the formulation previously showed, so i went ahead and made some

When I tried to add library from repository, I got the error:Unable to get the list of available libraries from repository.Can you tell me how to deal with it?

Hello to everyone, i have the following problem i can not solve. So on the one side I have consumers that need a certain amount of energy at a time. On the other side I have a generator plant that produce green electricity. The Problem is, that the demand can not alaways be satisfied by the generators. For this I use batteries. The are charged, if there is more then enough energy available.The express this mathematically, I used a if then formulation: For the charging I use:Demand(t) - Generator (t) >= 0 → Battery(t) = Battery(t-1)*(1-self-discharge-coeffizient)+((Demand(t)-Generator(t))*efficiency_Inverter*efficiency_Battery)For the dischargingDemand(t) - Generator (t) <= 0 → Battery(t) = Battery(t-1)*(1 - self_discharge_coeffizient)+((Demand(t)-Generator(t))/efficiency_Inverter)Demand(t), Generator(t) and Battery(t) are variables.self_discharge_coeffizient, efficiency are parameters I do not have any clue how to solve the problem in AIMMS. If anybody could help me, i would be v

Hi there,I´d like to know if SDP and SOCP formulations are supported by AIMMS?, I have not found any reference in the modelling manual nor any examples of that.Thanks in advance. 🙂

Hello, Im looking for a way to create a set where the data inside will be values from 1 to 100 ? What is the formula to put in Initial data ? Thank you 

Hi all, I would like to seek clarification regarding the disparities between MIP (Mixed Integer Programming) and RMIP (Relaxed Mixed Integer Programming) solvers. While I understand that RMIP converts integer variables into continuous variables, I would like to explore any other significant dissimilarities between these two solvers.Specifically, I am encountering fluctuations in the results of one of the variables when utilizing the MIP model as shown in the picture below. Despite the absence of any constraint-related issues, the values exhibit variability instead of remaining constant. Conversely, when employing the RMIP solver, the values remain consistent throughout (as presented in picture below). I am keen to understand the cause behind these fluctuations and any significant disparities between the MIP and RMIP solvers that could potentially explain this behavior. Any insights, explanations, or suggestions on how to address these fluctuations would be greatly appreciated too! Than

Hello, I have a problem.I created two sets i and j for the variable X_i,j.Now I want to add a constraint to see if the sum of all X_i,j with i="specific value” is equal to 10.My guess would be something like:sum[ ("Specific value”,j), variable(i,j) ] = 10;But this obviously doesn't work, otherwise I wouldn't be asking.

The variable X is with the index domain i, while the variable Y is with the index domain j. The number of element in j is twice that of i, which means J = 2*I when seeing these two index as number.Now I want to write a constraint:X(i) <= Y(2*i)How can I do this in AIMMS? 

Hi, I am trying to model the following constraint:with x as a nonnegative value indication the hours processed of job j-1 in time bucket t and Y as binary variable indicating that job j in time bucket t may start or not. The problem is that t is in the index domain and I need a summation over t’ based on t. How can I properly model this? I already have two indices for the set time buckets: t and h. But how do I model that x(i,j,t) is the same as x(i,j,h)? Preferably in one variable if that is possible? If I just simply say x(i,j,h) in the constraint I get the error: The parentheses in variable "x" do not match. Which is true since I modelled the variable as x(i,j,t).  

Hi! I’m working on my small project and I’m a beginner in programming and AIMMS. I tried to run the model that I have developed but it resulted into “Warning: After zero iterations CPLEX 22.1 concluded that an integer solution to MinimizeDailyCost does not exist.” I attach my model and data.I’m not sure where to start rectify this problem. Appreciate if anyone can help.

Hi,I am solving a huge MIP (481707 integer variables). I set the relative gap to 0% from CPLEX MIP settings. With such a huge model, the solver should take quite some time to solve. Just after 287466.11 sec (3.3 days), the model stop running and the solver status says 'Terminated by solver' why the gap is 1.27%. Why does this happen? I am attaching a screenshot. I'll appreciate any ideas on this. Thanks ! 

There is a time series variable A={a1,a2,a3...at}, and I want to constraint the fluctuation of the variable. I did this in AIMMS with the following way:1) I define a variable series_mean to calculate the mean of the series, 2) I define a constraint to make the variance of the series be no larger than 10000.   series_mean = sum(t,A(t))/T;sum(t,(A(t)-series_mean)^2)/T<=10000; However, this seems burden the computation and the solving time soars even though the constraint didn’t work in optimization. Like in one scenario, with or without the constraint I get the same result, however the solving time with the constraint is 10 times that in the case without this constraint. (The constraint is a must though) .So I hope to know is there a better way to do the same things in AIMMS?Thanks.

Dear AIMMS team, Trust you are doing well. I recently installed AIMMS version 4.94.3.3 and I only found two solvers namely: CBC 2.9 and IPOPT 3.11. I tried adding more solvers to it through the solver configuration but proved abortive. How can I add the following solvers to the version.Conopt, CPLEX, Baron, CP Optimizer, Gurobi, COPT, MINOS, ODH-CPLEX, OCTERATH, PATH, KNITRO, NETSOL. I have also attached the messages I am receiving. Thank you. 

Hi, Is there any way of looping through a for-loop backwards? The subset is ordered by user, for example {1,4,3,5}. I want to loop backwards so from 5 to 3 to 4 to 1.   

I defined a set with the element {1..25}, in the data it shows like the figure. What’s the matter? 

Is there anyway to export the convergence process in one solve?

Hi everyone, is there a predefined function to get the absolute value of variables?