Author: Andrew Mason (Team OpenSolver)

There’s an interview online at Chandoo.org with Dan Fylstra, the creator of Solver, the add-in which has made such a contribution in bringing optimization to the millions of Excel users.

Building good linear and integer programming models is not easy. However, I have just come across the AIMMS Optimization Modelling book which covers many important modelling ideas. The AMPL book is also a good reference that I can fully recommend. Enjoy. Andrew

We had a report yesterday from a user Daryl that BitDefender was reporting a possible virus infection on his PC that appeared to be connected with OpenSolver. Thanks to great work by Daryl and our programmer Jack, we identified this as a false positive (i.e. an incorrect report of a virus) being triggered by BitDefender’s ‘heuristics’. BitDefender was objecting to some of our VBA code, including one of our comments. (Note that I said comment, not actual code, and so this is definitely a case of BitDefender being overzealous!) We will tweak our next release to better avoid false reports such as these.

Thanks, again, to Daryl for contacting us with his concerns. Much appreciated.

Andrew

This user feedback helps summarise why we created SolverStudio, our free tool for Excel users that want to build bigger optimisation models:

Dear Andrew,
Couple of months ago you had advised me to solve [my OpenSolver] model (which takes 1.5 hours to even create set up file) in SolverStudio.

I followed your advise and now I would like to share my real life experience about such a big model.
While OpenSolver was solving my large problem in 2-2.5 hours (including setup and solution), SolverStudio GAMS formulation reduced the solution time to 2 minutes. I’d like to take this opportunity to thank everyone who developed such a tool. Also, SolverStudio greatly quickened up NEOS solver use. It was kind of painful to NEOS solver on its own…

I’m very pleased to see that the pioneers who played such a pivotal role in creating COIN-OR and all the great software that makes OpenSolver & SolverStudio possible have been awarded the INFORMS 2014 Impact Prize. Well done to Brenda Dietrich, JP Fasano, John Forrest, Lou Hafer, Brady Hunsaker, Laszlo Ladanyi, Robin Lougee, Ted Ralphs, and Matthew Saltzman for all their hard work over the years. They will receive their award at the INFORMS conference Award Ceremony this Sunday.

Associate Professor Ted Ralphs is organising a COIN-OR workshop:
https://sites.google.com/site/2015icsconference/home/coin-fest
at the Informs Computing Society (ICS) conference in January:
https://www.informs.org/Blogs/E-News-Blog/ICS-2015-Conference

Ted will be demo’ing both OpenSolver and SolverStudio at this event, and also giving an overview of all the other tools COIN-OR makes available.

Today, our downloads passed the 100,000 mark. Thanks to all the Engineering Science students who have contributed code to OpenSolver over the years, and all the users and beta testers who have helped us iron out the bugs and add more useful features.

Trying to sell optimisation to your colleagues? This IBM video does a good job:

https://www.youtube.com/watch?v=XrMNie-Nzk0&feature=youtu.be
Thanks to Michael Watson for linking to this from his blog.

One of our OpenSolver users recently worked with modelling guru Stu Mitchell to move his model from OpenSolver to SolverStudio. The OpenSolver model originally took 4 hours to solve. After simplifying the spreadsheet, this reduced to 2 hours. Stu created a SolverStudio version that solved the same problem in just 20 seconds. To quote our user: The conversion to SolverStudio has been an excellent improvement.

If you have a complicated spreadsheet, then you may also find that SolverStudio  gives much better solve times. Furthermore, the latest SolverStudio release includes ready-to-run models for many common problem formulations, which helps make the conversion even easier. Give it a go, and let us know how you get on.

Andrew

OpenSolver would not be possible without the CBC solver developed by the COIN-OR group. Working with colleagues Bob Fourer, Kevin Furman, William Hart and Michael Trick, we are preparing to nominate the initiators and founders of COIN-OR for the 2014 INFORMS Impact Prize. Thus we are soliciting testimonials to the impact that COIN-OR projects, and OpenSolver in particular, have had on diverse research and business activities.

We invite you to send us a paragraph or two describing how OpenSolver software has made a significant difference to your work and accomplishments. Please send your description by June 25 to me at email hidden; JavaScript is required Also feel free to send me any questions about what’s needed.

 

This is a nice OpenSolver application that gave savings of $1.1M annually:

https://smartech.gatech.edu/handle/1853/42172

Title:	Batching Outbound Shipments for Whirlpool Corporation
Author:	Bertolino, Michele ; Herbst, Ana ; Jones, Andy ; Liem, Adam ; Nemes, Travis ; O’Gorman, Melanie ; Russell, Samantha ; Sood, Eric
Abstract:	The team investigated the implementation of batch-picking shipments at a regional distribution center for Whirlpool Corporation, the world’s largest appliance manufacturer. An Excel-based optimization tool was created to strategically batch shipments to more effectively utilize carrying capacity of clamping forklifts across the network. Due to the decrease in labor hours, this resulted in savings of $1.1M annually.

Informs Transactions on Education has just published a special issue in honour of Paul Jenson who developed some excellent Excel tools for teaching operations research and management science. This special issue includes an article on SolverStudio. Cheers, Andrew

This guide,  Practical Guidelines for Solving Difficult Mixed Integer Programs,  might be useful for people looking for tips on how to solve difficult integer programming models.

I’ll be presenting on SolverStudio at the INFORMS conference in Minneapolis. Please come along to the Modeling Systems II session “MD08”, Monday Oct 07, 16:30 – 18:00, Level 2 – Room 200H to learn about SolverStudio, or to ask me OpenSolver questions! I look forward to seeing you there. Andrew