It is my honor, as the chair of the Department of Computer Sciences at the University of Texas at Austin, to welcome you all to this celebration of Edsger W. Dijkstra. I would like to thank the committee -- Vicki Almstrum, Allen Emerson, Warren Hunt, Jay Misra, and Ham Richards -- for organizing this event.
I would also like to welcome back to Austin, Ria Dijkstra. We are saddened by the circumstances but happy to see you Ria.
I would also like to welcome Dick Klaassen to Austin. Many of us knew Dick's wife, Netty van Gasteren, who was one of Edsger's PhD students. Netty's dissertation, On the Shape of Mathematical Arguments, was devoted to a theme both she and Edsger would play on for decades. The theme was that formality elucidates structure. Netty performed much of her research here, in the Tower, in the mid 80's. She too was a member of our family and her death this summer, on the heels of Edsger's, was another blow.
This evening, we are focused on Edsger's life and what he meant to us.
Without a doubt, a hundred years from now every computer scientist will study Dijkstra's ideas, including
to name but three.
How often can I list three great ideas attributed to one person and leave out many of his ideas that are more famous?
Dijkstra not only loved computer science -- with the emphasis on science -- but he loved language.
Of course, language is fundamental to our field. But Dijkstra's fascination with language transcended science.
He loved language as a tool for communication. He was fascinated with its nuances, with its precision, with its capacity for both clarity and wit.
Through that fascination he enriched us all with such technical phrases as
"structured programming,"
"deadly embrace,"
"dining philosophers,"
"weakest precondition,"
"guarded command",
"the excluded miracle", and
"semaphores".
He was also constantly teaching us -- students and colleagues alike. One of his central lessons was the importance of precision. He did most of his teaching through questions -- questions for which he often already knew the answer. He understood that the best way to teach was to make the student think and he did that most often -- and most irritatingly -- through his questions.
To this day I am careful about how I use the word "real" because of a question he asked during a talk I gave in 1975.
Dijkstra was perhaps first and foremost a teacher. He lived -- and I might add, died -- in a way that was true to this calling. Many of us are teachers 3 hours a week. Dijkstra stood apart because he was a teacher 24 hours a day. Even in non-scientific conversations he chose the role of teacher and his method was almost always to get us to think.
In our last conversation I said to him "Edsger, I will miss you." And he looked at me with a twinkle in his eye and said "Well, I won't miss you."
Dijkstra was a giant ... but intellectual giants are odd...
They distort the usual laws of perspective: as you get closer to them, they seem smaller -- more normal. Dijkstra was simply Edsger. He came to work in a t-shirt and shorts and sandals. He wore a cowboy hat on summer days. He supported KFMA...
Did we recognize his stature and his greatness?
Speaking for myself, I must confess: not always. I always respected his opinions -- scientific or otherwise -- and listened to his arguments. Of course, I did not always agree with him. But that was of less concern --- to either of us --- than that we listened to each other.
But I wish I had taken his class.
I wish I had found the time to attend the Austin Tuesday Afternoon Club.
Such regrets are, of course, just the stuff of life...
Rick Hehner spoke for many of us when, in his last letter to Edsger, he wrote:
"all of us have taught literally thousands of students, who take away thoughts that originated in your head. And your influence is not just technical. Your way of working, and your ethics, have become mine as well as I am able to emulate them. What I want to say is: thank you. With great admiration and affection, Rick"
Dijkstra was a giant.
To be parochial about it -- and to put it in perspective -- a hundred years from now, few will know -- and fewer still will care -- how well the football team played during the 20 years Dijkstra walked this campus. Few will care what programming language we taught or what percentage of our teaching was done by tenure-track faculty.
But every educated computer scientist will know that Dijkstra walked this campus.
The most fortunate of those students will read the original EWDs -- all 1300 of them -- and realize that here -- under this roof, among those trees, in that building -- was a true scholar, a man of letters, a scientist, and a teacher.
Most of the great scientists are synonymous with their universities. And their universities are great because of them, not vice versa. So it was with Dijkstra and the University of Texas at Austin.