AIMMS Language

I was wondering if there is a way in aimms to generate sol and lp files using original variable and constrain names which are used in aimms modelling, or alternatively, to figure out the correspondence between variables in the sol and lp files and those in the aimms model? Thanks

I need to provide an initial (staring) solution for a mixed integer programming from a solution file (file.sol) to help the solver (cplex) in finding the optimal solution faster, but I do not know how.  I need to mention that: I have changed the setting for cplex to “Use advanced basis” the file.sol has been created by aimms for the same MIP  My knowledge of aimms is basic  I  would appreciate if you could provide some details about variable initialisation. Thanks

Hi, I have a question regarding some best practices in terms of reading excel files with the axll library. Here, we have to specify the header / dataranges before reading. Often, we don't know exactly how many rows of data we have. We can of course set the max row number arbitrary large (or to the excel sheet row limit of 1,048,576), but that feels like a ‘dirty’ solution. Is there another way we can only read the rows which actually have data? Ideally, I would like some sort of functionality which ‘peeks’ into the file and tells us where the data is. Curious to hear possibilities in this regard. Thanks!

I am getting the following error when I try to open a project in 4.70: This project (with WebUI) opens just fine in 4.69.  What needs to be fixed? And how can I fix it?

Dear All, In many publications related to power system expansion planning, model validation is done by applying the developed model to a small system such as Garver 6 Bus and describing the result without detailed explanation to justify the model is valid or not. Is there any specific methods to validate the optimization model? Thank you very much.  

Can anybody suggest how can i eliminate the following error? Warning: After 66905692 iterations CPLEX 12.8 terminated and leastcost is still infeasible. 

Dear AIMMS Team, I am a PhD student in the UK and I have been trying to solve a non-linear non-convex optimisation problem with different solvers for a Journal Paper. The following are the CPU details: Intel Core i7 2.2GHz, 16GB RAM memory, 64-bit operating system. So far the solvers CONOPT 4.0 and IPOPT 3.11 have been able to solve the case without problems. Unfortunately, when I use MINOS the following error appears: Errors/Warnings Warning: Model status 13: Error no solution, Solver status 9: Error: Setup failure (see message window). Message Window For the MinCost 39239 columns have been generated of which only 31245 are non-empty. Calling MINOS for NLP of 34726 rows, 31245 columns and 109867 non-zeros. Calling MINOS to solve NLP model 'MinCost' and minimize GenCost. Generation required 0.406 seconds. MINOS error: Not enough memory for basis factorization. Required amount of memory: 2799 Mb. You could increase the value of the general solvers option 'solver workspace'. There is 1.7

Dear All, I want to model a variable that only can be applied for certaint set index. For example: Variable NPGMax {     IndexDomain: (i,g,ng)|ord(i) = 1 or ord(i) = 3 or ord(i) = 6; } where the variable NPGMax is only applied for index 1, 3, or 6 of set bus with index i. Is it possibel to do it dynamiclly where the value 1,3, or 6 can be assigned as an input parameter? Thank you very much.

Dear All, Is possible to retrieve MIP optimalilty gap and Solving Time for each solve in to a parameter? If so, how to do this? Thank you very much.

As some of you are aware (e.g. as discussed in product updates), we are currently developing an integration of Python into AIMMS. For this development, we are discussing whether we still should support Python-32 next to Python-64 (fyi, AIMMS Developer only will be delivered as 64-bit per 1/1/2020; AIMMS PRO has been 64-bit only for several years now). Curious to hear your thoughts! Please elaborate as much as possible when explaining your view.

Hello Members, i want to add a time restriction constraint in my model in which i have variable s(i,j,k) for time where i and j belongs to node and k belongs to vehicle.  i want to add a constraint which will ensure that each vehicle will not work more than 8 hours.  Provide the possible formulation against this constraint. Looking forward for response. 

Hi All,   I’m trying to use CPOptimizer giving an initial solution. I found AIMMS allows this in the “specific-solver option”. But according to  AIMMS website only CPLEX, GUROBI and CBC support solving with an initial solution. And I did not find a way to directly setup the initial solution in AIMMS for CPOptimizer. So does AIMMS allow read in an initial solution for CP? If yes, how should I set up this, like read in from another data file?   Thanks and happy holidays!

Dear all, how can I do the stochastic optimization in aimms?Best 

Dear,I have a binary variable in my model X(i,j,k,s) and I want that it assumes a value that I calculated in the deterministic model. For example I want that X(i,j,k,s)=X('Yorkshire and the Humber','MEA',k,s);How can I write this in aimms?I tried to write a constraint but after the run of the programme I don't have results for this variable.Thanks for your help. 

In May 2018 AIMMS announced a plan to deprecate compound sets in stages. Support for compound sets will be fully deprecated after January 1, 2020. To find out how to identify and remove compound sets from your model without losing functionality, read AIMMS Knowledge: Prepare for the Deprecation of Compound Sets. This article provides the following background information: Definition of compound sets in AIMMS Reason to deprecate compound sets Timeline to adapt your model Here is the article and here's how to prepare (and use set mappings)

When two AIMMS apps communicate with each other using the same identifiers, you may want to use the text format. Here we’ll provide a brief example of sharing persisting AIMMS data with text files.   Read more...

Hi dear community,   I have a constraint as sum((k,z1), y(b,k,z1,l,z2)) <= 1 and I want to add if statement to it: if k = l, then z1 cannot be equal to z2; if k<>l, then there’s no further constraint for z1 and z2. I tryed to add it like this: if k<>l then sum((k,z1), y(b,k,z1,l,z2)) <= 1 endif; if k=l then sum((k,z1)|z1<>z2, y(b,k,z1,l,z2)) <= 1 endif; The AIMMS through out the message “The scope of index "k" has not been specified.” like shown in the screenshot(I’ve highlighted where the error is-the first k appears in if statement). So my question is, is there a way to fix this constraint in the way that I want it to be? (maybe using element parameter)?   Thanks in advance!

After the software is installed, the script error will be prompted when the software is opened, as shown in the figure below  

Hi All,   I’m trying to compare solving a problem with CPLEX vs constraint programming in CPOptimizer. When I use CPOptimizer for my project, I found it could find the optimal solution (same with the optimal solution found by CPLEX) extremely fast (5s vs 350s in CPLEX). However,  the CPOptimizer couldn’t stop automatically because the Gap is still beyond 90% due to the best bound increasing extremely slowly...and it turned out the best bound finally reached the optimal objective value after ~3000s and then the CPOptimizer stopped. That’s confused me a lot. So my question would be: How does this “best bound” come from in constraint programming? Is it the same thing with lower bound in CPLEX? When a problem is very complex, is it normal to observe what I saw-the best bound increaseing very slowly? I do have the MTZ subtour elimination constraint in my problem which is famous for its weak LP relaxation. Will this be part of the reason why the best bound increase so slow? Is it possible to

Dear all, I have a matrix T(i,j,k,s).I want that for each s, i and j are equal.How can I do this?Best

Some years ago, before Microsoft Office 2010, life was – in some sense – easier for developers: Office was 32-bit, period. In our days, since the release of Microsoft Office 2010, things are a bit more complicated, as users can now have a machine with a 64-bit native version of Office installed as well. This means, for instance, that a 32-bit application using an ODBC driver to connect to an Access database might not work anymore, since the 32-bit ODBC driver might not exist on a machine with a 64-bit Office installation. In such a case, even though the user has a valid Office installation on his or her machine, the application may still display an error regarding the installation or the registration of the proper drivers on the local machine. Here

Hi dear community, I have a general question regarding the subtour elimination method of DFJ vs MTZ. The “CVRP” example on AIMMS website uses both methods to elinimate subtour and the result shows MTZ is faster than DFJ. However in the example, the MTZ is run together with the model while the DFJ is only used in the callback. So my question is, do we always run MTZ together with the model or it will actually give a better computation time if we use MTZ in callback just like DFJ? And actually in my current project, I’m trying to get a storage assignment solution (400 items to 400 locations) with the minimum total travel distance for the pickers picking multiple batches. Each batch will include at most 5 items. So for this problem, say if we have 1000 batches, it will be 1000 TSP problems among at most 5 locations. So in this case, will there be any huge difference for me to use DFJ vs MTZ since the n is actually relatively small in each batch?  Thanks in advance!

Hi,  I have the dongle usb in violet and just the license number that I know should work. When I try to install the license number, this message appears: the license file not found. In fact, I did not receive any license file. How can I solve this issue?   Thanks