In graduate school she was very much alone, though she was a grader for an undergraduate course taken by Raymond Johnson. In her first class, she was the only Black, the only woman. Her classmates ignored her completely, even terminating conversations if she came within earshot. She was denied a teaching assistantship, although she was an experienced (13 years) and excellent teacher. She wrote further:”I could not join my advisor and other classmates to discuss mathematics over coffee at Hilsberg’s cafe…. Hilsberg’s would not serve Blacks. Occasionally, I could get snatches of their conversation as they crossed our picket line outside the cafe.” She could not enroll in professor R.L. Moore class as he explicitly stated that he did not teach Blacks. Overlooking all this, one of her professors, complaining against the civil rights demonstrations, said to her: “If all those out there were like you, hard-working and studious, we wouldn’t have any problems.” Her reply: “If it hadn’t been for those hell-raisers out there, you wouldn’t even know me.”

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To see the structure hidden in this diagram we have to look at it through algebra and programs.

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As a senior researcher, I am saddened to see funding agencies, department heads, deans, and promotion committees encouraging younger researchers to do shallow research. As a reader of what should be serious scientific journals, I am annoyed to see the computer science literature being polluted by more and more papers of less and less scientific value. As one who has often served as an editor or referee, I am offended by discussions that imply that the journal is there to serve the authors rather than the readers. Other readers of scientific journals should be similarly outraged and demand change. The cause of all of these manifestations is the widespread policy of measuring researchers by the number of papers they publish, rather than by the correctness, importance, real novelty, or relevance of their contributions. [David Parnas]

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He was a real mathematician except that he only learned one little bit of mathematics and then didn’t learn any more. He was no practical organizer and, well, if you had Turing around in the place you wouldn’t get it going.

Looking back, what would you say was the significance of Turing’s 1936 Entscheidungs-problem paper?

I always felt people liked to make a song and dance. Something like the doctrine of the Trinity involved whereas to an engineer you’ve only got to be told about the stored program idea and you’d say at once “That’s absolutely first-rate, that’s the way to do it.” That was all there was to know.

There was no distinction in that paper that had any practical significance. He was lucky to get it published at all but I’m very glad he did. I mean [Alonzo] Churchl had got the same result by other methods.

I liked Turing; I mean we got on very well together. He liked to lay down the law and that didn’t endear him to me but he and I got on quite well. People sometimes say I didn’t get on with Turing but it’s just not true. But then I was very careful not to get involved.

From ACM Communications interview with Maurice Wilkes.

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The current system of publication in biomedical research provides a distorted view of the reality of scientific data that are generated in the laboratory and clinic. This system can be studied by applying principles from the field of economics. The “winner’s curse,” a more general statement of publication bias, suggests that the small proportion of results chosen for publication are unrepresentative of scientists’ repeated samplings of the real world. The self-correcting mechanism in science is retarded by the extreme imbalance between the abundance of supply (the output of basic science laboratories and clinical investigations) and the increasingly limited venues for publication (journals with sufficiently high impact). This system would be expected intrinsically to lead to the misallocation of resources. The scarcity of available outlets is artificial, based on the costs of printing in an electronic age and a belief that selectivity is equivalent to quality. Science is subject to great uncertainty: we cannot be confident now which efforts will ultimately yield worthwhile achievements. However, the current system abdicates to a small number of intermediates an authoritative prescience to anticipate a highly unpredictable future. In considering society’s expectations and our own goals as scientists, we believe that there is a moral imperative to reconsider how scientific data are judged and disseminated. (cite)

See my previous notes on refereeing in computer science.

Here

Here

Here

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[Boltzmann] Opposition to his ideas was harsh and his moods were volatile. Despondent, fearing disintegration of his theories,he hanged himself in 1906. It wasn’t his first suicide attempt, but it was his most successful.

This kind of expresses the mood of Janna Levin’s book about topology, the size of the universe, and all sorts of things that are too deep to even think about, like English apartments.  Silly physicists take everything too seriously.

New York.

How Did the Universe Get Its Spots?
Performance artist Laurie Anderson + astrophysicist Janna Levin
The first (and only) artist-in-residence at NASA engages in a free-form conversation with the novelist and professor of physics and astronomy at Barnard College. Levin teases apart the implications of black holes and the early conditions the universe; her first novel, A Madman Dreams of Turing Machines, won the PEN/Bingham Fellowship for Writers.

Date & Time: Saturday, March 6, 2010, 6:00 PM
Location: Rubin Museum of Art, 150 West 17th Street, New York, NY 10011

One mathematician

a very different one

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There is nothing wrong with the approach described but I fail to see that there is anything novel here either. Circuits have been modeled as state machines since the 60s (e.g. Booth 67), there is a wealth of literature on the correspondence between state machines, automata and strings, and so forth. All of this has been done before, and more completely.

I am sure that one could look in most computer science curricula and find almost all of this material being taught at the undergraduate level.

I’m really embarrassed for the entire profession here. Of course circuits have been modeled as state machines – well before 1967 in fact. Booth’s 1967 book is one of innumerable surveys.  The paper showed an alternative way of representing state machines and illustrated their use on the time sensitive behavior of combinational circuits where they are not usually employed because the number of states is so great as to overwhelm standard methods.  The specific methods used in this papers, as far as I know, are not used elsewhere in the literature – and I still don’t know any different because the CAV2010 reviewer was unable to provide a reference. To me, this is a mark of humbug. Look, if you are going to tell some poor author that their work is retelling some well known tale, you should at the very least be able to point to the well known explications. Creditably enough, CAV2010 offers a rebuttal period for reviews: but even given a second chance, and an explicit request for a reference, both the author of the review and the program committee failed.  An assertion is made that the material is covered in “most computer science curricula” and when challenged, the assertion is just left as is. No wonder so much of academic computer science is mired in stale repetition of old material when basic standards of scientific rigor are discarded by the people who are supposed to be enforcing the rules.

I don’t want to seem entirely ungrateful for the work of the reviewers: one of whom gave a perfectly rational and solid reason for rejecting the paper.

Conclusion: an elegant paper, but doomed for CAV by lack of any attempt at automation or convincing evidence that automation of the methods described would be a scientific advance.

I can’t really argue with that. The paper does not either describe automation or attempt to make an argument of why automation would succeed – although I am in no doubt about the second question. Perhaps the paper is not suitable by reason of the focus of the conference. But of 4 reviews, this reviewer was the only one who appeared to understand the material. One of the other reviewers actually responded to the rebuttal with this:

About the KR theorem and feedback, an ordinary finite state automaton “encodes” implicitly the feedback information of the underlying sequential circuit in its states, so I would be surprised that the theorem is not applicable to digital circuits with feedback

Ok. The KR (Krohn-Rhodes) theory is based on a decomposition called “loop free”. Let me type that again LOOP FREE.  The theory is concerned with the decomposition of state machines into pipelines where components can be ordered so that the output of component i depends only on the input to the system and the outputs of components j<i . What I show in the paper is how to describe one of the simplest and most beautiful achievements of Computer Engineering, a SR-latch via the interconnection of state machines that represent logic gates. The SR-latch is constructed with cross-coupled gates where the output of each gate feeds back into the input of the other gate. When the output of gate G1 feeds into the input of gate G2 and the output of G2 feeds into the input of G1, we have what is known in the technical literature as a “loop”. While the reviewer would not be surprised if a loop-free product could be used to describe a loop,  the comment makes me doubt his/her grasp on the basics of the material (BTW: the identity of this reviewer is known to me, but I’ll leave to him/her to respond or not).

One of the other reviewers included (among others) two comments  that I noted were wrong, but were not modified or defended.

2. The term “propagation delay”: It seems that you blend different concepts into this single term, namely the duration that an input has to be held stable in order to be sure that it will be reflected by the output and the latency of a circuit in forwarding such a sufficiently stable input to its outputs. While your model, by lumping together the two into a single latency, is a conservative approximation of more detailed models, you may want to make sure that your terminology is in accordance with accepted terminology. it.

Here the reviewer apparently does not understand the difference between latch time and propagation delay. Have those definitions changed since I last looked at a digital circuits book? “The propagation delay t_p of a signal path is the amount of time that is takes for a change in the input signal to produce a change in the output signal” (Wakerly, 1990, P 76).

3. The abstraction of your latch leaves the case (set,reset): (0,0) -> (1,1) unspecified, which is fine. You may, however, want to mention this detail in the accompanying text.

Ah well, the second week of Digital Electronics II is not for everyone. “However if we negate both inputs simultaneously, the latch goes into an unpredictable next state and it may in fact oscillate or enter the metastable state.” (Wakerly 1990 P355). See it’s really not so hard to provide a citation.

There’s actually a lot more to ridicule in these reviews – I’ll post more on request, but I do want to look at one more comment from Reviewer4.

I still believe that this paper lacks motivation and new results for being accepted. As the author says himself, the paper is about a technique for specifying automata, and I am not convinced why not doing it directly with automata, using standard and well-studied techniques. For instance, given that the propagation delays of the gates are modeled using discrete time, why embedding them directly into the definition of gates (even underspecified), instead of modelling them directly with I/O finite state machines (or sequential circuits with feedback)?

It’s not at all clear to me what  modeling a gate as a sequential circuit with feedback even means. In terms of digital circuit engineering, a gate is a combinational circuit, not a sequential circuit. The cool thing about a cross-coupled latch is that the feedback produces sequential properties from combinational circuits. So this comment is quite obscure. On the other hand, I/O automata (from Lynch/Tuttle) are a good example of the augmented automata that I’m deliberately avoiding because of their mathematical ugliness. You can take classical state machines and add all sorts of stuff to them: clocks, fairness conditions, oracles depending on the Axiom of Choice, steroids, flavor enhancers, and so on.  The “standard and well-studied techniques” Reviewer4 has in mind are almost certainly timed and hybrid automata which are types of augmented automata. But the argument made in my paper is that the austere flavor of classical automata theory is strong enough to model timing without additives. Rather than responding to this argument, the Reviewer asks why I don’t use the “standard” methods with additives.

It’s certainly possible that the work described in the paper lacks interest to anyone but me ( the “crank” hypothesis). But lacking credible reviews, it’s hard to make any conclusion at all.

A response.

Hi Victor, good to hear from you.

About your CAV paper, don’t get pathetic. Each PC member has to review in a short time numerous papers and he cannot afford the time needed to give full feedback to the author of a paper which shows strict disconnectedness with contemporary verification. Instead of thanking (or even apologizing) to the PC members for the fact that they bothered to read your paper and give you some feedback (one minute browsing was sufficient to predict its rejection) you still complain and make useless noise.

I will send you my rejected paper and its reviews, if you enjoy reading such things.

Pathetic! Ouch.

In other matters

For a variety of reasons, this reminds me of  a conference I attended in Salvador Brazil many years ago which was like something out of a Magical Realism novel involving lachrymose Argentines who longed to teach meringue, drum bands, unbearably tedious talks, dreamlike missed airplane sequences,  a moment when I was sure that Amir Pnueli, his wife, and myself were about to be assaulted while we were discussing the Israeli novel Blue Mountain which according to Pnueli, was set in his home town, random appearances of gigantic fashion models, an abandoned building in which rooster fighting was taking place,  the most delicious beer ever drunk in world history, a peculiar lecture on Fra Angelico and the relationship between New Mexico and Hassidism (“you must look at the white spaces between the words”) , a hero named Hercules, and much more. I returned from the trip to a faculty meeting chaired by Jean Louis Lassez.  Did any of it even really happen? The conference also provided me with an astounding article review: the reviewer explained that I had made an elementary error when I proved something about a set without taking into account the ordering of the set. Even the Baal Shem Tov would not be able to discern meaning in such a comment.

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And as an added bonus – the great “Recursive Functions” book by Rozsa Peters contains the following remarkable note that has nothing to do with the mathematics, but a lot to do with how mathematicians think.

Ok, “the present conditions” were kind of dramatic.

1956: Soviet troops overrun Hungary

At least 1,000 Soviet tanks are reported to have entered Budapest and troops deployed throughout the country are battling with Hungarian forces for strategic positions.
The Soviet air force has bombed part of the Hungarian capital, Budapest, and Russian troops have poured into the city in a massive dawn offensive.

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EURYI applications were first submitted to the relevant national research councils, who could nominate a specific number of candidates. This selection cut the proportion of women from one-quarter to one-fifth. Each national research council oversaw a drop in the number of selected women. In Spain, where nearly a third of the applicants were women, not one was nominated. The all-male Spanish list emerged with the highest success rate in the later European rounds, nearly three times the average. From 133 national nominees, European evaluation committees created a shortlist of 67, causing the largest drop in the proportion of women: 9.90+/-.5% of men applying made the European short list , but only 4.7+/-1.4% of women did. [cite]

For more see here.

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GENERALLY ACCEPTED AS TRUE BY RESEARCHERS IN DISTRIBUTED SYSTEMS

• - The client-server paradigm is a good one
• - Microkernels are the way to go
• - UNIX can be successfully run as an application program
• - RPC is a good idea to base your system on
• - Atomic group communication (broadcast) is highly useful
• - Caching at the file server is definitely worth doing
• - File server replication is an idea whose time has come
• - Message passing is too primitive for application programmers to use
• - Synchronous (blocking) communication is easier to use than asynchronous
• - New languages are needed for writing distributed/parallel applications
• - Distributed shared memory in one form or another is a convenient model

and then Rob Pike’s refutation entitled “Andy Tanenbaum hasn’t learned anything”. A key point that comes up later in the discussion is Tanenbaum’s (incorrect) assertion that a “factor of two” performance loss is nothing to worry about. The date of the discussion is interesting, because in a few years the Linux Tsunami washed away most of the landscape of this discussion. As for my contribution it is very disturbing to see that I have not learned much about those topics in the last 14 16 years.

It is clear that Rob Pike was right on many more issues than AST, but that seemed clear at the time too.

Subject: Andy Tanenbaum hasn’t learned anything

From: rob@alice.att.com (research!rob)
Date: 6 Apr 92 20:06:28 GMT
Approved: comp-os-research@ftp.cse.ucsc.edu
Newsgroups: comp.os.research
Organization: AT&T, Bell Labs
Sender: usenet@darkstar.ucsc.edu

The implementers of Plan 9 are baffled by Andy Tanenbaum’s recent posting.
We suspect we are not representative of the mainline view, but we disagree
at some level with most of the “GENERALLY ACCEPTED” truths Andy claims.
Point by point:

- The client-server paradigm is a good one
Too vague to be a statement. “Good” is undefined.
- Microkernels are the way to go
False unless your only goal is to get papers published.
Plan 9′s kernel is a fraction of the size of any microkernel we know and offers more functionality and comparable or often better performance.
- UNIX can be successfully run as an application program
`Run’ perhaps, `successfully’ no. Name a product that succeeds by running UNIX as an application.
- RPC is a good idea to base your system on
Depends on what you mean by RPC. If you predefine the complete set of RPC’s, then yes. If you make RPC a paradigm and expect every application to build its own (c.f. stub compilers), you lose all the discipline you need to make the system comprehensive.
- Atomic group communication (broadcast) is highly useful
Perhaps. We’ve never used it or felt the need for it.
- Caching at the file server is definitely worth doing
True, but caching anywhere is worthwhile. This statement is like saying ‘good algorithms are worth using.’
- File server replication is an idea whose time has come
Perhaps. Simple hardware solutions like disk mirroring solve a lot of the reliability problems much more easily. Also, at least in a stable world, keeping your file server up is a better way to solve the problem.
- Message passing is too primitive for application programmers to use
False.
- Synchronous (blocking) communication is easier to use than asynchronous
They solve different problems. It’s pointless to make the distinction based on ease of use. Make the distinction based on which you need.
- New languages are needed for writing distributed/parallel applications
`Needed’, no. `Helpful’, perhaps. The jury’s still out.
- Distributed shared memory in one form or another is a convenient model
Convenient for whom? This one baffles us: distributed shared memory is a lousy model for building systems, yet everyone seems to be doing it. (Try to find a PhD this year on a different topic.)

How about the “CONTROVERSIAL” points? We should weigh in there, too:

- Client caching is a good idea in a system where there are many more nodes than users, and users do not have a “home” machine (e.g., hypercubes)

What?

- Atomic transactions are worth the overhead

Worth the overhead to whom?

- Causal ordering for group communication is good enough

We don’t use group communication, so we don’t know.

- Threads should be managed by the kernel, not in user space

Better: have a decent process model and avoid this process/thread dichotomy.

Rob Pike
Dave Presotto
Ken Thompson
Phil Winterbottom

Distributed shared memory – an idea that never made any sense to me.

[edited to reflect the passage of time][ and again to add the Pike/Presott/Thompson/Winterbottom text]

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