发信人: zyingp(C砣S月NEXT), 信区: CompSci. 本篇人气: 196
标 题: We Are Sorry to Inform You-著名文章被拒
发信站: 小百合BBS (Sat May 27 14:48:21 2006)
at http://csdl2.computer.org/persagen/DLAbsToc.jsp?resourcePath=/dl/mags/co/&t
oc=comp/mags/co/2005/12/rztoc.xml&DOI=10.1109/MC.2005.423
We Are Sorry to Inform You
Simone Santini, University of California, San Diego
Once upon a time there was a little-known patent clerk in Bern who received a
disappointing annual performance review in '05 (www.norvig.com/performance-rev
iew.html).
E.W. DIJKSTRA
"Goto Statement Considered Harmful." This paper tries to convince us that the
well-known goto statement should be eliminated from our programming languages
or, at least (since I don't think that it will ever be eliminated), that progr
ammers should not use it. It is not clear what should replace it. The paper do
esn't explain to us what would be the use of the "if" statement without a "got
o" to redirect the flow of execution: Should all our postconditions consist of
a single statement, or should we only use the arithmetic "if," which doesn't
contain the offensive "goto"?
And how will one deal with the case in which, having reached the end of an alt
ernative, the program needs to continue the execution somewhere else?
The author is a proponent of the so-called "structured programming" style, in
which, if I get it right, gotos are replaced by indentation. Structured progra
mming is a nice academic exercise, which works well for small examples, but I
doubt that any real-world program will ever be written in such a style. More t
han 10 years of industrial experience with Fortran have proved conclusively to
everybody concerned that, in the real world, the goto is useful and necessary
: its presence might cause some inconveniences in debugging, but it is a de fa
cto standard and we must live with it. It will take more than the academic elu
cubrations of a purist to remove it from our languages.
Publishing this would waste valuable paper: Should it be published, I am as su
re it will go uncited and unnoticed as I am confident that, 30 years from now,
the goto will still be alive and well and used as widely as it is today.
Confidential comments to the editor: The author should withdraw the paper and
submit it someplace where it will not be peer reviewed. A letter to the editor
would be a perfect choice: Nobody will notice it there!
E.F. CODD
"A Relational Model of Data for Large Shared Data Banks." This paper proposes
that all data in a database be represented in the form of relations—sets of t
uples—and that all the operations relative to data access be made on this mod
el. Some of the ideas presented in the paper are interesting and may be of som
e use, but, in general, this very preliminary work fails to make a convincing
point as to their implementation, performance, and practical usefulness. The p
aper?s general point is that the tabular form presented should be suitable for
general data access, but I see two problems with this statement: expressivity
and efficiency.
The paper contains no real-world example to convince us that any model of prac
tical interest can be cast in it. Quite the contrary, at first sight I doubt t
hat anything complex enough to be of practical interest can be modeled using r
elations. The simplicity of the model prevents one from, for instance, represe
nting hierarchies directly and forces their replacement with complicated syste
ms of "foreign keys." In this situation, any realistic model might end up requ
iring dozens of interconnected tables—hardly a practical solution given that,
probably, we can represent the same model using two or three properly formatt
ed files.
Even worse, the paper contains no efficiency evaluation: There are no experime
nts with real or synthetic data to show how the proposed approach compares wit
h traditional ones on real-world problems. The main reason for using specializ
ed file formats is efficiency: Data can be laid out in such a way that the com
mon access patterns are efficient. This paper proposes a model in which, to ex
tract any significant answer from any real database, the user will end up with
the very inefficient solution of doing a large number of joins. Yet we are gi
ven no experimental result or indication of how this solution might scale up.
The formalism is needlessly complex and mathematical, using concepts and notat
ion with which the average data bank practitioner is unfamiliar. The paper doe
sn't tell us how to translate its arcane operations into executable block acce
ss.
Adding together the lack of any real-world example, performance experiment, an
d implementation indication or detail, we are left with an obscure exercise us
ing unfamiliar mathematics and of little or no practical consequence. It can b
e safely rejected.
A. TURING
"On Computable Numbers, with an Application to the Entscheidungs Problem." Thi
s is a bizarre paper. It begins by defining a computing device absolutely unli
ke anything I have seen, then proceeds to show—I haven't quite followed the n
eedlessly complicated formalism—that there are numbers that it can't compute.
As I see it, there are two alternatives that apply to any machine that will e
ver be built: Either these numbers are too big to be represented in the machin
e, in which case the conclusion is obvious, or they are not; in that case, a m
achine that can't compute them is simply broken!
Any tabulating machine worth its rent can compute all the values in the range
it represents, and any number computable by a function—that is, by applying t
he four operations a number of times—can be computed by any modern tabulating
machine since these machines—unlike the one proposed here with its bizarre m
echanism——have the four operations hardwired. It seems that the "improvement
" proposed by Turing is not an improvement over current technology at all, and
I strongly suspect the machine is too simple to be of any use.
If the article is accepted, Turing should remember that the language of this j
ournal is English and change the title accordingly.
C.E. SHANNON
"A Mathematical Theory of Communication." This paper is poorly motivated and e
xcessively abstract. It is unclear for what practical problem it might be rele
vant. The author claims that "semantic aspects of communication are irrelevant
to the engineering problems," which seems to indicate that his theory is suit
able mostly for transmitting gibberish. Alas, people will not pay to have gibb
erish transmitted anywhere.
I don't understand the relevance of discrete sources: No matter what one does,
in the end, the signal will have to be modulated using good old-fashioned vac
uum tubes, so the signal on the "'channel"' will always be analogical.
A running example would have helped make the presentation clearer and less the
oretical, but none is provided. Also, the author presents no implementation de
tails or experiments taken from a practical application.
Confidential comments to the editor: The only thing absolutely wrong with this
paper is that it doesn't quite "resonate" with what the research community fi
nds exciting. At any point, there are sexy topics and unsexy ones: these days,
television is sexy and color television is even sexier. Discrete channels wit
h a finite number of symbols are good for telegraphy, but telegraphy is 100 ye
ars old, hardly a good research topic.
The author mentions computing machines, such as the recent ENIAC. Well, I gues
s one could connect such machines, but a recent IBM memo stated that a dozen o
r so such machines will be sufficient for all the computing that we'll ever ne
ed in the foreseeable future, so there won't be a whole lot of connecting goin
g on with only a dozen ENIACs!
IBM has decided to stay out of the electronic computing business, and this jou
rnal should probably do the same!
C.A.R. HOARE
"An Axiomatic Basis for Computer Programming." I am not sure I understand this
article. It claims to be about programming, but it doesn't contain a single l
ine of code.
The paper introduces the idea that certain inference rules can be associated t
o statements in a program and used to show that the program does indeed comput
e what it is supposed to. I have some reservations that the program's purpose
can be defined in the terms the author claims—we all know how fuzzily defined
the features of real programs are—but the idea, if suitably justified, might
have some merit. However, in its current state, the work is far too prelimina
ry to be considered for a journal. It may well be insufficient for any kind of
publication, so I would advise the author to try a workshop at which these ki
nds of preliminary ideas will be more likely to find a home.
Before the author attempts journal publication, he should complete this work i
n several respects. The method assumes that the function of a program can be s
pecified as the final value of certain variables. This is an unrealistic view
for interactive programs: The author should show how his method fits with the
industry's standard way of specifying requirements. He should also extend the
method to be applicable to a standard programming language such as COBOL or PL
/I and provide the details of his implementation, possibly with a few graphics
to show how the system works in practice.
Until this is done, I fear the work is too tentative and preliminary for publi
cation.
R.L. RIVEST, A. SHAMIR, AND L. ADELMAN
"A Method for Obtaining Digital Signatures and Public-Key Cryptosystems." Acco
rding to the (very short) introduction, this paper purports to present a pract
ical implementation of Diffie and Hellman's public-key cryptosystem for applic
ations in the electronic mail realm. If this is indeed the premise, the paper
should be rejected both for a failure to live up to it and for its irrelevance
.
I doubt that a system such as this one will ever be practical. The paper does
a poor job of convincing the reader that practicality is attainable. For one t
hing, there is the issue of the number n used to factor the message.
The scheme's security relies on the factorization of n in prime factors taking
so long as to be impractical. The authors also stress that the encryption alg
orithm must be fast and—if their application, electronic mail, is to make sen
se—the algorithm should run on all sorts of machines. Let us be generous and
assume that every computer user has access to a latest-generation minicomputer
such as the VAX. This 32-bit machine's speed considerations limit the choice
of n to n < 232 = 4,294,967,296. Granted, this is a large number, but by the v
ery results of the paper's Table 1, it can be factored in a couple of hours. S
carcely a time margin that will grant security!
Further, as the authors acknowledge, a data encryption standard already exists
, supported by both the US National Bureau of Standards and IBM, currently the
largest computer manufacturer. It is unlikely that any method that runs count
er to this standard will be adopted in any significant degree. True, the IBM m
ethod presents the problem of distributing the encryption key, but their metho
d is a standard and we must live with it. Instead of creating nonstandard meth
ods that will soon be dead for lack of users, the authors should try to extend
the standard and devise ways to distribute the encryption keys securely.
Finally, there is the question of the application. Electronic mail on the Arpa
net is indeed a nice gizmo, but it is unlikely it will ever be diffused outsid
e academic circles and public laboratories—environments in which the need to
maintain confidentiality is scarcely pressing. Laboratories with military cont
racts will never communicate through the Arpanet! Either normal people or smal
l companies will be able to afford a VAX each, or the market for electronic ma
il will remain tiny. Granted, we are seeing the appearance of so-called microc
omputers, such as the recently announced Apple II, but their limitations are s
o great that neither they nor their descendants will have the power necessary
to communicate through a network.
The introduction is only two paragraphs long, the relevant literature is not p
resented or cited, and there is virtually no comparison with the relevant work
in the area. In summary, it looks as if this paper is a mathematical exercise
with little originality (the authors claim that most of their ideas come from
other papers), too far from practical applicability, running against the esta
blished standards, and with a declared application area of dubious feasibility
. Not the kind of material our readers like to see in the journal. Reject.
And the rest is history.
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