It's now almost a week since the tragic event, and yet, it's so hard to believe that Rajeev is no more, especially when one sees the photograph in the obituary. That smile, a little shy, a little mischievous, was the same when he was a student here. Anyone who had taught Rajeev could not but be impressed by his class. At the same time, he was not at all competitive-- if he did well, which he did, it was because doing well was so natural for him.
I met him only infrequently since 1983, but I'd get in touch with him whenever any need arose, either for myself or for a student. Rajeev would render his help promptly and he'd answer e-mails without any delay. Only now I realize, reading about him, how busy though he had been all through. I recall that in 1999 June I went to his office to meet him. When I reached, one undergraduate student of his theory of computation course was there already, to clear some doubts. From the questions the student was asking, it was evident that the student had put in hardly any effort for the course till then. Most of us would be very impatient with such students. Rajeev, however, was not only patient but also friendly-- I still remember how beautifully, without using the whiteboard, Rajeev explained, just through words, why the problem of checking if an input TM would ever make a left move when started on a blank tape is decidable. I could see that the student understood the argument, and he left the office very happy. It was a lesson to me-- I realized that people of true excellence have no problems at all in accepting shortcomings in others.
These years at IITK we teach theory of computation from Hopcroft, Motwani, Ullman, and as we mention that this is the text, we invariably mention with great pride and happiness that the author Motwani was our student. That pride from now on will be coupled with great sorrow.