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In Honor of Alan Turing

Thirty-two of the 39 living A.M. Turing Award laureates gathered in San Francisco to pay tribute to "the father of CS" and discuss the past, present, and future of computing.
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Turing Award laureates at the Turing Centenary Celebration
The Turing Centenary Celebration featured the largest single gathering of Turing Award laureates in computer science history.

One hundred years after the birth of Alan Mathison Turing, a growing list of countries around the world have been fashioning celebrations to mark the centenary of his birth on June 23, 1912. Which makes it no mean feat to create an event that is unique—and also memorable.

But the ACM A.M. Turing Centenary Celebration on June 15 and 16 at San Francisco’s Palace Hotel was “unique and breathtaking,” according to Ed Lazowska who, along with approximately 1,050 other attendees, witnessed, for the first time, the gathering in one place of 32 of the 39 living ACM A.M. Turing Award laureates.

“They were the two best days I’ve spent professionally in many years,” says Lazowska, who holds the Bill & Melinda Gates Chair in Computer Science & Engineering at the University of Washington. “Not only was it a treat to hear from so many Turing laureates, but the audience was a ‘Who’s Who’ of the field. The fact that all branches of computer science were represented—from the most theoretical to the most applied—made it far more stimulating than a normal narrowly focused symposium.”

In order to make the event as accessible as possible, a group of ACM SIGs covered the attendance fees and Google, Intel, and Microsoft provided student transportation and lodging. While the initial preparation had been for 500 attendees, that number quickly doubled—and more.

“Not only was it a treat to hear from so many Turing laureates,” says Ed Lazowska, “but the audience was a ‘Who’s Who’ of the field.”

The organizers had two objectives, according to Vint Cerf, ACM president, who served as general chair of the conference, along with program cochairs Mike Schroeder, John Thomas, and Moshe Vardi. The first was to recognize Turing’s contribution to computer science. The second was to accomplish something that no one else could do. And since ACM has honored its most significant contributors as Turing awardees, the organization wanted as many laureates as possible to participate.

“It was quite stunning to have as many awardees respond positively,” says Cerf, “and then not only to show up, but also to actually speak or be on a panel or in a brief lecture. So we succeeded well beyond our expectations.”

The Turing Centenary’s two-day schedule was arranged so “there were plenty of opportunities for attendees to meet face-to-face with the Turing laureates,” adds Cerf, who received the 2004 Turing Award with Robert Kahn. “Without exception, all of them were accessible and accommodating and were happy to talk to anyone who wanted to talk to them. There were lots of people getting autographs. And students had an opportunity to talk to people who had written their textbooks.”

“For me, one of the two most remarkable events was the panel on ‘Turing: The Man’ consisting of people who had met Turing or his mother and had stories to tell about their experiences,” says John White, ACM’s CEO. “[1973 Turing recipient] Charlie Bachman had a great story about, when it was announced he had won [for his work in database technology], his wife had no clue as to who Turing was. She went to the library and found a biography of him written by his mother, Sarah Turing. Charlie and his wife managed to track her down in a nursing home outside of London and they visited her and talked about her son and the award. That was just one of so many amazing little anecdotes that came out of that panel.

“The other remarkable event was the talk, ‘Lambda Calculus, Then And Now,’ by [1976 Turing recipient] Dana Scott [who introduced the idea of nondeterministic machines to automata theory],” says White. “Dana did his Ph.D. with Alonzo Church, the same person with whom Turing did his Ph.D. The way Dana and the other panelists tied the areas they worked in to the fundamental contributions of Turing was really amazing—and I learned a lot.”

Lazowska recalls being particularly impressed with remarks by 1994 Turing recipient Raj Reddy who, as a member of the panel on artificial intelligence, brought the audience to its feet when he responded to the question “What are the next AI challenges?”

“What he said—and I’m paraphrasing—is there are so many millions and millions of books in the world that, if he did nothing but read 24 hours a day, he could only read 40,000 in his lifetime,” says Lazowska. “But wouldn’t it be something if a program could be created, a sort of personal assistant, to read all those books—and then whisper in his ear when a piece of information was relevant to what he was working on or talking about? He really captured peoples’ imaginations with how he described his vision—and hundreds of people started applauding.”

Cerf recalls being particularly moved by an incident involving futurist Paul Saffo who emceed the event and quipped about the need for “all two women attending the conference” to walk over to the photographer who was waiting to take their picture.

“He was, of course, referring to the fact that historically women have been underrepresented in computer science,” explains Cerf.

However, it turned out that nearly 150 women were at the Turing Cenenary and some were offended by Saffo’s remark.

“Saffo apologized,” recalls Cerf, “and took advantage of the opportunity to point out that discrimination exists not only against women but also minorities in computer science. And there needs to be a change because it is shortsighted for us not to take advantage of every brain available to solve some of the serious problems facing us as a society. Saffo made a beautiful, eloquent apology that was very impressive.”

Other high points of the program include:

  • The formal award ceremony when computer scientist and philosopher Judea Pearl received the 2011 A.M. Turing Award for his work in artificial intelligence.

“He has been contributing to very fundamental ideas in probalistic and causal reasoning for decades,” says Cerf, “and, in the end, companies like Google have come to rely on Bayes’ theorem in myriad ways. So it was particularly gratifying to see him win.”

  • 2003 Turing laureate Alan Kay’s homage to Ivan Sutherland on the 50th anniversary of Sketchpad, Sutherland’s Ph.D. thesis that led to the first graphical user interface. Kay recreated the Sketchpad display of the famous Sketchpad “truss bridge” demo.

“It was terrific how Kay did it live and interactively,” says Lazowska. “I mean, this is the work that, back in the 1960s, influenced Kay’s Smalltalk programming language work in the 1970s.”

  • A hardware panel moderated by University of California, Berkeley professor David Patterson in which 1988 Turing laureate Ivan Sutherland made an argument favoring asynchronous logic over synchronous. “In Turing’s day, logic was expensive; it was slow,” said Sutherland. “Relative to logic, wires were almost free and very fast. Since then, the cost of logic and wires has totally interchanged. Today, logic is fast and almost free, but wires are slow and costly.”

“That’s been a debate that’s gone on for decades,” says Cerf, “but Sutherland’s was the most cogent, terse argument I’d ever heard, delivered in a powerful way that was really beautiful.”

  • 2008 Turing laureate Barbara Liskov who made the case that “producing software is still difficult and we can do better.” She added that production languages are complicated—too complicated to teach programming and computational thinking, which is why these courses are increasingly taught in languages like Python and Ruby that don’t have any support for modularity. Liskov urged the audience to “design languages all over again; the only thing that absolutely matters is support for modularity and encapsulation.”

Turing laureate Barbara Liskov urged the audience to “design languages all over again; the only thing that absolutely matters is support for modularity and encapsulation.”

  • 2009 Turing laureate Charles Thacker commented that “there are a surprising number of people who program day-by-day but don’t actually understand how a computer works. That limits you,” he said. “It’s important to have a fairly good idea of what goes on at the bottom. Cutting it off at the C compiler seems to me to be quite limiting.”
  • A screening of the movie Code-breakers, a drama-documentary about Turing and his work at Britain’s code-breaking center in Bletchley Park during World War II. For a time, Turing headed up the section responsible for German naval cryptanalysis.
  • A visit to the nearby Computer History Museum in Mountain View where a 25,000-square-foot exhibition, “Revolution: The First 2000 Years of Computing,” covers the history of computers in 20 galleries from the invention of the abacus to the Internet.

See the Turing Centenary Celebration Webcast at

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UF1 Figure. Raj Reddy and Fran Allen

UF2 Figure. Donald Knuth addresses a panel.

UF3 Figure. Charles Bachman (left) and Judea Pearl

UF4 Figure. The Turing Centenary Celebration featured the largest single gathering of Turing Award laureates in computer science history. The key below identifies the 30 laureates in this group photo. Missing, but in attendance, were Joseph Sifakis and E. Allen Emerson (both 2007 recipients).

UF5 Figure. ACM A.M. Turing Award Laureates: 1. Charles Bachman 1973 Award Recipient 2. Alan C. Kay 2003 Award Recipient 3. Raj Reddy 1994 Award Recipient 4. Fran Allen 2006 Award Recipient 5. Butler Lampson 1992 Award Recipient 6. William Kahan 1989 Award Recipient 7. Robert Kahn 2004 Award Recipient 8. Judea Pearl 2011 Award Recipient 9. Fernando Corbató 1990 Award Recipient 10. Vinton Cerf 2004 Award Recipient 11. Niklaus Wirth 1984 Award Recipient 12. Ken Thompson 1983 Award Recipient 13. Ivan Sutherland 1988 Award Recipient 14. Frederick P. Brooks, Jr. 1999 Award Recipient 15. Barbara Liskov 2008 Award Recipient 16. Juris Hartmanis 1993 Award Recipient 17. Leonard Adleman 2002 Award Recipient 18. Adi Shamir 2002 Award Recipient 19. Leslie Valiant 2010 Award Recipient 20. Edmund M. Clarke 2007 Award Recipient 21. Robert Tarjan 1986 Award Recipient 22. Edward Feigenbaum 1994 Award Recipient 23. Stephen Cook 1982 Award Recipient 24. Richard Stearns 1993 Award Recipient 25. Dana Scott 1976 Award Recipient 26. Charles Thacker 2009 Award Recipient 27. John Hopcroft 1986 Award Recipient 28. Richard Karp 1985 Award Recipient 29. Ron Rivest 2002 Award Recipient 30. Donald Knuth 1974 Award Recipient

UF6 Figure. Alan C. Kay

UF7 Figure. Adi Shamir (and E. Allen Emerson)

UF8 Figure. Leslie G. Valiant

UF9 Figure. Edmund M. Clarke

UF10 Figure. Stephen A. Cook

UF11 Figure. Niklaus Wirth

UF12 Figure. Ivan Sutherland

UF13 Figure. Barbara Liskov

UF14 Figure. Vint Cerf (left) and Robert Kahn

UF15 Figure. Edward Feigenbaum

UF16 Figure. Joseph Sifakis

UF17 Figure. Fernando Corbató

UF18 Figure. Frederick P. Brooks, Jr. (left) and Charles Thacker

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