The first article in this issue is a discussion paper that was co-authored by Kesar Singh. Sadly, Professor Singh passed away before the article was finalized, and he did not read the final version and did not contribute to the rejoinder. Since the paper is being published posthumously, we find it appropriate to publish an obituary together with the paper. We join Professors Regina Liu and Min-ge Xie, who wrote the obituary, in remembering Kesar and in recognizing his many contributions.