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Research & AIMMS Questions

Ask questions and exchange ideas related to AIMMS modeling — whether you're tackling academic research, exploring algorithmic challenges, or working through AIMMS language and application issues.

  • 158 Topics
  • 358 Replies
158 Topics
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pamjsnnNewcomer
asked in Research & AIMMS Questions
Subtraction of Element Valued Expressions

Hi! I have a constraint (shown at the photo below) wherein two sets need to be subtracted. I tried introducing another set Kw with a definition of k-Ks but it says subtraction of element valued expressions require the set range to be equal, but the ranges domain set "Subblock" and set "Candidate_Subblocks" differ. Identifier: Subblock Index: k Identifier: Candidate_Subblock Index: Ks Identifier: Subblock_Difference Subset of: Subblock, Candidate_Subblocks Index: Kw Definition: k-Ks above is the current code I have. Do you have any Idea on how I can code my constraint?

2159
deannezhang
AIMMS Champ
Arthur
ArthurFormer AIMMSian
posted in Research & AIMMS Questions
How Machine Learning can help Optimization modeling

Dear AIMMS communians😉, We started some years ago at AIMMS an investigation on how machine learning and optimization can work together, or how machine learning algorithms could help optimization modeling. During the AIMMS Summit, in addition to the very interesting presentation from Ger Koole, we presented a 45 min workshop demoing an interesting use case on this matter - Optimizing a power production plan with renewable resources. This example showcases a combination between machine learning and robust optimization. I'm sharing now our slides, as well as the model itself, written in AIMMS. This example was greatly inspired and helped by Gianmaria Leo, an IBM researcher we met at the EWG POR Conference in Bologna in March 2019. Thank you Gianmaria! You may find his open source repository here. The idea of sharing it now is to start a discussion, share our upcoming progress, gather your thoughts, inspirations and potential contributions. We believe this subject woul

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Arthur
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pamjsnnNewcomer
asked in Research & AIMMS Questions
Objective Function Problem:

Hi, the "objective function" of my program is read as a variable in AIMMS. All the parameters in the objective function already have a data read from excel. My problem is, AIMMS keeps on saying "the scope of index i has not been specified" when I try to specify the index, the program won't run because it will say that the objective function should be a free scalar variable. What should I do?

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M
MartenNewcomer
asked in Research & AIMMS Questions
Creating Confidence Intervals

Hi all, For our program, we have a 3*36 parameter input that we want to vary using a normal distribution for 1000 times in order to save the objective values to, eventually, create confidence intervals. We have the 1000 variation matrices, but we do not know manage to load these into AIMMS and let the program save the 1000 objective values. On the other hand, it is impossible to copy-paste these manually. Could you perhaps give us some advise on how to implement such a for-loop in AIMMS? Kind regards, Marten

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Chris Kuip
AIMMSian
Jess Es
Jess EsGrand Master
published in Research & AIMMS Questions
Modeling the forest

This interview, originally published in 2014, comes from our Tech Blog archives. Strategic Forest Management Model (SFMM) was among the first applications of AIMMS and is still going strong. Please note, some cited data is a bit dated, but we think that the story is still worth sharing. Ontario’s Ministry of Natural Resources takes us through decades of effective forest management Forest ecosystems are highly complex and influenced by a diversity of factors. Sustainable forest management is therefore an ongoing and constantly evolving process which requires an integrated approach. Government bodies, such as The Ontario Ministry of Natural Resources (OMNR), must conform to provincial policies and standards, while taking economical and ecological considerations into account to arrive at optimal forest management policies. OMNR manages 27 million ha of Ontario’s public forest and has been using an AIMMS-based model for this purpose since 1994. The Strategic Forest Management Model ,

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Jess Es
Jess Es
Jess EsGrand Master
published in Research & AIMMS Questions
Using operations research to solve pressing global issues

This article, originally published in 2013, comes from our Tech Blog archives. As such, some cited data is a bit dated, but we think that the story's value illustrating practical application of OR still holds up. The mathematical story behind North Star Alliance’s POLARIS More than 35 million people worldwide are infected with HIV or are living with AIDS, and approximately 70% live in Sub-Saharan Africa. Mobile populations, such as long distance truck drivers, are particularly at risk of contracting and transmitting the virus. In 2007, TNT Express and the United Nations World Food Programme joined forces to form North Star Alliance (North Star) - a public-private partnership that is working to increase access to health services along major transport corridors in sub-Saharan Africa. ORTEC, a longstanding AIMMS partner, joined North Star in 2008 to design their award-winning Corridor Medical Transfer System (COMETS), which enables North Star staff to access and monitor patient

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Jess Es
Patrick
Administrator
PatrickAdministrator
posted in Research & AIMMS Questions
Practical Guidelines for Solving Difficult Mixed Integer Linear 2 Programs

When the going gets tough ... we at AIMMS use this paper a lot! Even with state-of-the-art hardware and software, mixed integer programs can require hours, or even days, of run time and are not guaranteed to yield an optimal (or near-optimal, or any!) solution. In this paper, we present suggestions for appropriate use of state-of-the-art optimizers and guidelines for careful formulation, both of which can vastly improve performance. http://inside.mines.edu/~anewman/MIP_practice120212.pdf Are you using this as well? You can add 'your bible' as a reply.

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Patrick
Administrator
Patrick
Administrator
PatrickAdministrator
posted in Research & AIMMS Questions
Watch this Ted Talk about Optimization and Machine Learning

A nice Ted Talk, by Marco Lubbecke, about Optimization and Machine Learning. See here.

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Patrick
Administrator
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