The first time I heard of Chris Byrnes was at a visit to MIT in 1978. Professor Sanjoy Mitter told me that there was a new and very talented Assistant Professor at Harvard whom I just had to meet. We could not find him at that time, but I met him shortly thereafter at a conference, and we immediately struck a common cord. I invited him to the University of Kentucky, where I was then a professor, and this resulted in our first paper. This was the beginning of a long collaboration, to which Chris brought deep mathematical insight and a plethora of advanced mathematical tools -- but most of all the beginning of a long and deep friendship.

In 1985 Chris spent the spring semester at the Royal Institute of Technology (KTH) in Stockholm, to where I had moved two year earlier. Together we co-chaired the 1985 International Symposium on the Mathematical Theory of Networks and Systems (MTNS 85), which became a big success, in large part due to Chris.

During the last thirty years Chris and I have co-authored some 30 papers and co-edited four books. This collaboration was extremely stimulating. Chris was an enthusiastic and generous co-worker, and he had a quicker mind than anyone else I know. He also had an almost encyclopedic knowledge of large portions of mathematics, and working with him was major learning experience. On top of that he had a great sense of humor.

When he died in Stockholm, he was just in his first year of a three-year appointment at KTH as a Distinguished Visiting Professor under the Strategic International Recruiting program of the Swedish Foundation of Strategic Research. He had big and enthusiastic future plans on how he would contribute the intellectual climate at KTH. Just before he died he submitted the final revised version of a invited survey for the Notices of the American Mathematical Society on topological methods for nonlinear oscillations, which to his delight was very highly praised by the referees and the editor. Chris is very much missed by people at KTH where he was admired for the power of his mind and his spirit of generosity.