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96 COMPUTER Published by the IEEE Computer Society 0018-9162/12/$31.00 © 2012 IEEE
EDUCATION
Might Turing Have Won a Turing Award?
W hile we’re honor-ing Alan Turing 100 years after his birth with many special
events, including workshops and conferences, a simple question seems relevant: If Alan Mathison Turing (AMT) had not tragically died by his own hand in 1954, and the Turing Award (TA) had been created anyway, would he have received the award?
IMAGINE THIS SCENARIOImagine, if you can, that Turing
lived, the award was created, and we found a letter addressed to the chair of the award committee, which dis-cussed his case in 1966.
I think the letter might have looked like this—all names have been redacted.
Dear xxxxxxx:As you requested, the subcom-
mit tee met and discussed the recommendation of AMT for this award. We followed your guidelines and did not consider any alterna-tive candidates, but only looked into AMT’s work.
We also followed your advice that we should not consider any of his work in code breaking done at Bletch-
ley Park during the war. While this work likely was of immense impor-tance and saved countless lives, our subcommittee is in no position to evaluate his particular contributions. The work still is officially secret, and we agree with you, in your capacity as chair, that there are other ways more appropriate to honor his war contribution.
Executive summaryAMT has worked in many areas,
and in each he has made an original and important contribution. This is both the strength and the weakness of his case. In no area does his work show the depth that one might wish to see for the recipient of this award. Often his work is in setting up a clean framework that makes progress pos-sible for others. In no case does his work have the depth that we see for other awards. While this comparison with existing fields may be unfair, the entire committee agrees that the depth of his work is not its strength.
The committee does agree that AMT has the great ability to exam-ine a problem, see to its core, and state it, often in a new way. This has sometimes helped solve the problem, and other times it helped state the
problem in a way that should allow others to make further progress. We all agree on this.
Let’s now turn to the discussion of some of his key contributions.
ComputabilityAMT’s major contribution in this
area is his paper, “On Computable Numbers, with an Application to the Entscheidungsproblem.” This paper is notable because it gives a clear and compelling definition of what a com-putable real number is.
The model he proposes is based on an imagined simple mechanical machine and is quite clever. Of course the question of how to define comput-ability is not new and was certainly studied first by Kurt Gödel and others.
We do agree that AMT’s model has much to offer and is easier to think about than alternatives like those based on the lambda calculus—the latter is the work of Church and Kleene. We expect that the machine model will definitely lead to addi-tional insights in the future.
AMT also gives a surprising result in his simple proof that none of his machines can solve the Entscheid-ungsproblem. His proof of this result is strikingly simple, using what we
Richard J. Lipton Georgia Tech
A provocative tale highlights Alan Turing’s special ability to provide clarity to complex computing issues.
JUNE 2012 97
Editor: Ann E.K. Sobel, Department of Computer Science and Software Engineering, Miami University; [email protected]
this work alone should be enough for seriously considering AMT for the TA.
Work in other areasAs stated earlier, AMT has worked
in many other areas. None of these seem sufficient to merit receiving the TA, but the committee feels that we should at least mention this work. It does demonstrate the immense and unique breadth of his powers as a scientist.
The Riemann zeta hypothesis asks whether all the nontrivial zeroes of
the zeta function lie on the “critical line.” AMT did not make any prog-ress on proving this, but did suggest a clever method for testing the hypothesis.
The difficulty is that computing the exact location of a zero of a func-tion like the zeta function is almost impossible. But AMT showed that he could in principle use known meth-ods of number theory for counting the number of zeroes on the critical line.
He actually did this calculation for a modest range, and found that all the zeroes are where they should be. Clearly, this method may and probably will be extended in the future. The subcommittee wishes to thank the experts who took the time to explain this result to us. However, this work falls short of demonstrating an algorithmic pro-cedure to find counterexamples if the Riemann hypothesis is false, so it does not meet the AMT’s own high standard.
AMT also wrote a machine pro-gram that is capable of playing chess. He simulated the machine play by hand and lost a game to a colleague—although his automated player later beat that colleague’s wife. The com-
mittee finds this work in line with his work on “can a computer think?” But we feel that computer chess is solely an amusing side issue. As one of our subcommittee members put it, “There is no way that a machine will ever beat even a good club player, let alone the best chess player in the world.” The chair agrees completely.
Finally, AMT’s latest work is on mathematical aspects of biology, spe-cifically morphogenesis. We believe this work has potential, but clearly it is very preliminary at this time.
The committee’s recommendation
I must report that our subcommit-tee is strongly divided. All agree that AMT’s work is stellar, but there is not a consensus on whether he should be this year’s recipient of the TA.Sincerely,xxxxxxxxxxxxxxxSubcommittee Chair
W ith all due respect to this great scientist, in my opinion, as this ficti-
tious letter indicates, the answer to the question of whether Alan Turing would receive the Turing Award is not clear.
Richard J. Lipton is the Frederick G. Storey Chair in Computing at Georgia Tech. Contact him at [email protected]. He thanks Kenneth W. Regan for his comments on a draft of this article.
now know as the Halting Problem, but again this raises some depth questions. In particular, the proof is based on methods that Gödel used in his proof of the Incompleteness Theorem. The proof AMT gives also was not the first; that apparently was given by Church.
All these proofs rely on the diag-onal method proposed by Cantor in 1891 in his second proof that the real numbers are uncountable. Sev-eral committee members felt that the close relationship between these two ideas was a weakness: Cantor proved that all reals are not countable; AMT proved that all computable reals are not “countable” in a computability sense.
PhilosophyAMT’s major philosophical contri-
bution is “Computing Machinery and Intelligence.” This paper is his most original work, in the opinion of the committee. In it, he raises the ques-tion of whether mechanical devices can “think.” His brilliant idea is that while it seems to be impossible to provide a formal scientific defini-tion of this question, he does. After all, what is thinking? AMT cuts right to the core of the matter and sug-gests a Gedankenexperiment that makes great sense. He argues that if a mechanical device can pass his test, then it should be said to think.
The committee members agree that this is a strikingly original idea. Again, the committee was split on whether the suggestion that there is now a possible objective definition of thinking is sufficient.
The committee felt that further study into the ideas put forth here is needed, and perhaps it is premature at this time to make an award based on this work. Again, some of the commit-tee raised the depth issue. A brilliant definition, which is what this paper supplies, is not necessarily a deep result.
The chair wishes to state explicitly that he does not agree and believes
Alan Turing demonstrated an immense and unique breadth of powers as a scientist.
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