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Bixby, Gu, and Rothberg leave ILOG

I arrived at the INFORMS Practice Meeting, and one of the first people I met was Bob Bixby. I had heard some rumors, and noticed that the affiliation on his badge was Rice University, so I was eager to chat with him. I wrote about Bixby last year when he was the IFORS Distinguished Lecturer at the EURO Conference. I think Bixby has been the most influential person in our field over the last fifteen years or so, and that influence has been primarily through a computer code he created. Though he began his career as a top-notch combinatorial mathematician, he decided at one point to write the world’s best linear programming code. This code, called CPLEX, has had a tremendous influence on the practice of operations research, greatly expanding our field’s reach and influence. Bixby’s company was eventually bought by ILOG, a company that also does constraint programming and business rules systems (see Simon Holloway’s view of ILOG from someone versed in business rules), and ILOG has consistently improved CPLEX and provided support for the team developing it. Bixby has had a number of roles within ILOG, including Chief Science Officer.

Bixby, along with two on the CPLEX team, Ed Rothberg and Zonghao Gu, have left CPLEX in the last few months. This puts the IP/LP software world in a tremendous state of flux. On the positive side, three of the best people in our field will be able to spread their skills to other companies (Bob was cagey on where he is thinking about going, and I have not talked to Rothberg or Gu). On the negative side, there are now questions about two (with the Fair Isaac purchase of Dash Optimization) of the top codes that underly much of linear/integer programming based research and practice. Of course, CPLEX has a large (15 person perhaps) development team, and no one is irreplaceable, but that is a lot of change in a short period.

8:50 PM Correction. Ed Rothberg was not on the CPLEX team when he left ILOG. Further corrections as conditions warrant!

9:40 Addition.  Just so the following is not buried in the comments, here is the response from Irv Lustig from ILOG:

Further corrections to Mike’s post:

Bob Bixby has not been working on CPLEX for 4 or 5 years. Ed Rothberg has not been working on CPLEX for 2 years. Both of them had been working on ILOG’s FPO product. So only Gu has left the CPLEX R&D team.

As mentioned by Mike, ILOG acquired CPLEX over 10 years ago, and it is quite unusual in the software industry for a founder of an acquired company to remain more than 4 years after the acquisition. We were fortunate that Bob stayed for the 10+ years that he did.

I was also one of the original CPLEX developers, and I have not touched the code in over 10 years, moving on to other roles within ILOG. It is a testament to CPLEX and ILOG that we have replaced Bob, Ed and myself with new developers, and we have recently hired very good talent to improve the CPLEX product. The CPLEX product will survive just fine after these departures of our friends and colleagues.

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  1. Irv Lustig | April 13, 2008 at 10:46 pm | Permalink

    Further corrections to Mike’s post:

    Bob Bixby has not been working on CPLEX for 4 or 5 years. Ed Rothberg has not been working on CPLEX for 2 years. Both of them had been working on ILOG’s FPO product. So only Gu has left the CPLEX R&D team.

    As mentioned by Mike, ILOG acquired CPLEX over 10 years ago, and it is quite unusual in the software industry for a founder of an acquired company to remain more than 4 years after the acquisition. We were fortunate that Bob stayed for the 10+ years that he did.

    I was also one of the original CPLEX developers, and I have not touched the code in over 10 years, moving on to other roles within ILOG. It is a testament to CPLEX and ILOG that we have replaced Bob, Ed and myself with new developers, and we have recently hired very good talent to improve the CPLEX product. The CPLEX product will survive just fine after these departures of our friends and colleagues.

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  1. Michael Trick’s Operations Research Blog | October 10, 2008 at 8:25 pm | Permalink

    […] had previously written about the exit of Gu, Rothberg, and Bixby from Ilog. I was curious where they would end up: Google, […]