We Are Sorry to Inform You

December 2005 

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The Profession

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-review.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 programmers should not use it. It is not clear what should
replace it. The paper doesn't explain to us what would be the use of the
"if" statement without a "goto" 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
alternative, 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 programming 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 than 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 facto standard and we must live with it. It will take more than the
academic elucubrations of a purist to remove it from our languages.
Publishing this would waste valuable paper: Should it be published, I am as
sure 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 tuples—and that all the operations relative to
data access be made on this model. Some of the ideas presented in the paper are
interesting and may be of some use, but, in general, this very preliminary work
fails to make a convincing point as to their implementation, performance, and
practical usefulness. The paper?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
practical interest can be cast in it. Quite the contrary, at first sight I
doubt that anything complex enough to be of practical interest can be modeled
using relations. The simplicity of the model prevents one from, for instance,
representing hierarchies directly and forces their replacement with complicated
systems of "foreign keys." In this situation, any realistic model might
end up requiring dozens of interconnected tables—hardly a practical
solution given that, probably, we can represent the same model using two or
three properly formatted files.
Even worse, the paper contains no efficiency evaluation: There are no
experiments with real or synthetic data to show how the proposed approach
compares with traditional ones on real-world problems. The main reason for
using specialized file formats is efficiency: Data can be laid out in such a
way that the common access patterns are efficient. This paper proposes a model
in which, to extract 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 given no experimental result or indication of how this
solution might scale up.
The formalism is needlessly complex and mathematical, using concepts and
notation with which the average data bank practitioner is unfamiliar. The paper
doesn't tell us how to translate its arcane operations into executable block
access.
Adding together the lack of any real-world example, performance experiment, and
implementation indication or detail, we are left with an obscure exercise using
unfamiliar mathematics and of little or no practical consequence. It can be
safely rejected.

A. TURING

"On Computable Numbers, with an Application to the Entscheidungs
Problem." This is a bizarre paper. It begins by defining a computing
device absolutely unlike anything I have seen, then proceeds to show—I
haven't quite followed the needlessly 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 ever be built: Either these numbers are too big
to be represented in the machine, in which case the conclusion is obvious, or
they are not; in that case, a machine 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 the 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 mechanism——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
journal is English and change the title accordingly.

C.E. SHANNON

"A Mathematical Theory of Communication." This paper is
poorly motivated and excessively abstract. It is unclear for what practical
problem it might be relevant. The author claims that "semantic aspects of
communication are irrelevant to the engineering problems," which seems to
indicate that his theory is suitable mostly for transmitting gibberish. Alas,
people will not pay to have gibberish 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
vacuum tubes, so the signal on the "'channel"' will always be
analogical.
A running example would have helped make the presentation clearer and less
theoretical, but none is provided. Also, the author presents no implementation
details 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 finds exciting. At any point, there are sexy topics and unsexy ones:
these days, television is sexy and color television is even sexier. Discrete
channels with a finite number of symbols are good for telegraphy, but
telegraphy is 100 years old, hardly a good research topic.
The author mentions computing machines, such as the recent ENIAC. Well, I guess
one could connect such machines, but a recent IBM memo stated that a dozen or
so such machines will be sufficient for all the computing that we'll ever need
in the foreseeable future, so there won't be a whole lot of connecting going on
with only a dozen ENIACs!
IBM has decided to stay out of the electronic computing business, and this
journal 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 line of code.
The paper introduces the idea that certain inference rules can be associated to
statements in a program and used to show that the program does indeed compute
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
preliminary 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 kinds of preliminary ideas will be more likely to find a home.
Before the author attempts journal publication, he should complete this work in
several respects. The method assumes that the function of a program can be
specified 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
publication.

R.L. RIVEST, A. SHAMIR, AND L. ADELMAN

"A Method for Obtaining Digital Signatures and Public-Key
Cryptosystems." According to the (very short) introduction, this paper
purports to present a practical implementation of Diffie and Hellman's
public-key cryptosystem for applications 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
thing, 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
algorithm must be fast and—if their application, electronic mail, is to
make sense—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 very results of the paper's Table 1, it can be factored in a
couple of hours. Scarcely 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 counter to this standard will be adopted in any significant degree.
True, the IBM method presents the problem of distributing the encryption key,
but their method is a standard and we must live with it. Instead of creating
nonstandard methods 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
Arpanet is indeed a nice gizmo, but it is unlikely it will ever be diffused
outside academic circles and public laboratories—environments in which
the need to maintain confidentiality is scarcely pressing. Laboratories with
military contracts will never communicate through the Arpanet! Either normal
people or small companies will be able to afford a VAX each, or the market for
electronic mail will remain tiny. Granted, we are seeing the appearance of
so-called microcomputers, such as the recently announced Apple II, but their
limitations are so 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
presented 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
established 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.

Simone Santini is a project researcher at the University of California, San
Diego. Contact him at ssantini@sdsc.edu.