Eulogy for a Discrete Polymath

Professor Mendu Rammohan Rao [6th August 1941 - 24th May 2025]

My Dear Ram,     

When I was a PhD student and young researcher at the Operations Research Center at MIT, I had decided to work in combinatorial optimization and integer programming. It thrilled me to see the names of compatriots:  Mendu Rammohan Rao, Katta G Murty, USR Murty, Ravi Kannan and R. Chandrasekharan spoken of as thought leaders in this field. It was then my great fortune to get to know all of them well enough to have their greatness rub off a little on me. The relationship with you Anna went far beyond a professional one and lasted over 40 years. Over the years, I followed you to return to Indian academia from the US, followed you as a recipient of the M.C. Puri award in Operations Research and as the President of the Operational Research Society of India - a trail of legacies laid by the legendary P.C. Mahalanobis,  the founder of the Indian Statistical Institute.

I first met you thanks to of all things – NATO – a reflection perhaps of how advanced mathematics and technology in the West are driven by military industrial complex. NATO used to fund the annual summer school called ARIDAM – the Applications of Research in Discrete Applied Mathematics – which were hosted by the Hungarian mathematicians Peter Hammer and Endre Boros at Rutgers University. About a 100 leading discrete math researchers were invited. You and your buddies Manfred Padberg and Michele Conforti  were regulars from NYU as was I from Purdue. We stayed for a few weeks in the dormitories at Rutgers and just did discrete math all day and ended up in the pubs in New Brunswick at night.

We also had many great experiences traveling the world and attending conferences in exotic places. We even ended up in the Amazonian forests near Manaus after attending a conference in Rio. I recall fishing for Piranha in one of the tributaries of the Amazon and your holding a small crocodilian in your bare hands. I will have to search our storage bins at home to recapture the look on your face in the photographs I took.

This period in the 80’s was an exciting research time for both of us. Michele Conforti, Gerard Cornuejols (at CMU) and you were cranking out the extraordinary “Decomposition of Balance Matrices” which eventually earned the 3 of you the Fulkerson Prize (the Nobel equivalent in Combinatorics). For the non-mathematicians reading this eulogy, a balanced matrix is made of 0’s and 1’s and contains no square submatrix of odd size with exactly two 1’s in each column and row. Combinatorial optimization of gigantic scale on balanced matrices can be effectively solved by good algorithms. The unsolved problem was a good algorithm for recognizing a balanced matrix which you three musketeers solved.  In those days, I was cranking on the combinatorics of logical inferencing in collaboration with John Hooker, another ARIDAM friend at Carnegie Mellon University. I would run into your collaborator Gerard there and your delightful PhD Advisor Gerald Thompson a pioneer in Operations Research at CMU.

On your visit to Purdue, you stayed at home with us in West Lafayette in the late 80s. This is a memory etched in my mind. You were already advancing the balanced matrices results and gave some lectures on it. My graduate student Kalyan Talluri was excited by your work and wrote his MS thesis in 1987 on “Linear Balanced Hypergraphs” in which he figured out a short proof of one of your key Lemmas. Kalyan was a big fan of yours and kept saying “he is such a great man but has no ego!” a description I am sure many who knew you will concur with.

We both eventually moved back to Bangalore, you at IIM-B and I at IISc. We both got involved in various institution building activities both administrative and entrepreneurial. A common friend of ours, Dr Venkat Chandrasekar helped me with my entrepreneurial journey and served with you at IIM-B and ISB as a professor of entrepreneurship.  You and I somehow found time to get away from it all and write a series of pedagogic pieces on our love of the foundational mathematics and algorithmic ideas in linear and combinatorial optimization. I did pull you into working on biology and wrote a paper on algorithms for protein folding on lattices. We must have spent many hundreds if not thousands of hours meeting, discussing and writing. A debt of gratitude to our spouses Uma and Uma (both WCC alumni) for allowing us this luxury. I have compiled these two collected works of our joint writings for the two families to preserve.

I has taken me a year to reconcile with losing you. There was one more paper to write on the clever use of discrete mathematics in solving hard logistics problems using quantum computing. Dr. Krishna Palem who overlapped with you at NYU, brought both us together again a couple of years back to collaborate with him on this. Just as we were starting the validate your key insights on this problem, we got news of your falling ill and eventually of your passing.  It was fortunate that Krishna Palem, Venkat Chandrasekar and I were able to dash to Hyderabad from Bangalore in time to pay our last respects a year back. I have truly missed your gentle smile and the glint in your eye when we touched on a topic of mutual interest. We are all so happy to be gathered here again this year to remember you with respect, admiration and affection.

Vijay Chandru

vijaychandru@iisc.ac.in

May 24^th 2026

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