Addenda to recent articles 200811
Earlier I discussed an interesting technique for flag variables in Bourne shell programs. I did a little followup research. I looked into several books on Unix shell programs, including:Linux Shell...
View ArticleTriples and Closure
Lately I've been reading Lambek and Scott's Introduction to Higher-Order Categorical Logic, which is too advanced for me. (Yoneda Lemma on page 10. Whew!) But you can get some value out of books that...
View ArticleThe loophole in the U.S. Constitution: recent developments
Some time ago I wrote a couple of articles [1][2] on the famous story that Kurt Gödel claimed to have found a loophole in the United States Constitution through which the U.S. could have become a...
View ArticleArchimedes and the square root of 3, revisited
Back in 2006 I discussed Archimedes' calculation of the approximate value of π. In the calculation, he needed rational approximations to several irrational quantities, such as √3, and pulled...
View ArticleHigher-Order Perl: nonmemoizing streams
The first version of tail() in the streams chapter looks like this: sub tail { my $s = shift; if (is_promise($s->[1])) { return $s->[1]->(); # Force promise } else { return $s->[1]; } }...
View ArticleAmusements in Hyperspace
[ Michael Lugo's post on n-spheres today reminded me that I've been wanting for some time to repost this item that I wrote back in 1999. ] This evening I tried to imagine life in a 1000-dimensional...
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A simple trigonometric identity
A few nights ago I was writing up notes for my category theory reading group, and I wanted to include a commutative diagram on three objects. I was using Paul Taylor's stupendously good diagrams.sty...
View ArticleMaybe energy is really real
About a year ago I dared to write down my crackpottish musings about whether energy is a real thing, or whether it is just a mistaken reification. I made what I thought was a good analogy with the...
View ArticleMore Uzi-clubbing: a counterexample
Last year I wrote an article about iterating over a hash, searching for a certain key. Larry Wall called said this was like "clubbing someone to death with a loaded Uzi", because the whole point of a...
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Stupid crap
This is a short compendium of some of the dumbest arguments I've ever heard. Why? I think it's because they were so egregiously stupid that they've been bugging me ever since. Anyway, it's been on my...
View ArticleThe junk heap of (blog) history
A couple of years ago, I said: I have an idea that I might inaugurate a new section of the blog, called "junkheap", where unfinished articles would appear after aging in the cellar for three years,...
View ArticleStupid crap, presented by Plato
Yesterday I posted:"She is not 'your' girlfriend," said this knucklehead. "She does not belong to you." Through pure happenstance, I discovered last night that there is an account of this same bit of...
View ArticleMilo of Croton and the sometimes failure of inductive proofs
Ranjit Bhatnagar once told me the following story: A young boy, upon hearing the legend of Milo of Croton, determined to do the same. There was a calf in the barn, born that very morning, and the boy...
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Second-largest cities
A while back I was in the local coffee shop and mentioned that my wife had been born in Rochester, New York. "Ah," said the server. "The third-largest city in New York." Really? I would not have...
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Worst error messages this month
This month's winner is:Line 319 in XML document from class path resource [applicationContext-standalone.xml] is invalid; nested exception is org.xml.sax.SAXParseException: cvc-complex-type.2.3:...
View ArticleMost annoying phrase known to man?
I have been wasting time, those precious minutes of my life that will never return, by eliminating the odious phrase "known to man" from Wikipedia articles. It is satisfying, in much the same way as...
View ArticleProduct types in Java
Recently I wanted a Java function that would return two Person objects. Java functions return only a single value. I could, of course, make a class that encapsulates two Persons: class Persons2 {...
View Article"Known to Man" and the advent of the space aliens
Last week I wrote about how I was systematically changing the phrase "known to man" to just "known" in Wikipedia articles. Two people so far have written to warn me that I would regret this once the...
View ArticleBipartite matching and same-sex marriage
My use of the identifiers husband and wife in Thursday's example code should not be taken as any sort of political statement against same-sex marriage. The function was written as part of a program to...
View ArticleNo flimping
Advance disclaimer: I am not a linguist, have never studied linguistics, and am sure to get some of the details wrong in this article. Caveat lector. There is a standard example in linguistics that is...
View ArticlePeriodicity
The number of crank dissertations dealing with the effects of sunspots on political and economic events peaks every eleven years.
View ArticleA child is bitten by a dog every 0.07 seconds...
I read in the newspaper today that letter carriers were bitten by dogs 3,000 times last year. (Curiously, this is not a round number; it is exact.) The article then continued: "children ... are 900...
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Gray code at the pediatrician's office
Last week we took Katara to the pediatrician for a checkup, during which they weighed, measured, and inoculated her. The measuring device, which I later learned is called a stadiometer, had a bracket...
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Dijkstra was not insane
Recently, a reader on the Higher-Order Perl discussion mailing list made a remark about Edsger Dijkstra and his well-known opposition to the break construction (in Perl, last) that escapes prematurely...
View ArticleYou think you're All That, but you're not!
I have long been interested in term rewriting systems, and one of my long-term goals is to implement the Knuth-Bendix completion algorithm, described by Knuth and Bendix in their famous paper "Word...
View ArticleOn failing open
An axiom of security analysis is that nearly all security mechanisms must fail closed. What this means is that if there is an uncertainty about whether to grant or to deny access, the right choice is...
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World's shortest explanation of Gödel's theorem
A while back I started writing up an article titled "World's shortest explanation of Gödel's theorem". But I didn't finish it, and later I encountered Raymond Smullyan's version, which is much shorter...
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Another short explanation of Gödel's theorem
In yesterday's article, I said: A while back I started writing up an article titled "World's shortest explanation of Gödel's theorem". But I didn't finish it... I went and had a look to see what was...
View ArticleMonads are like burritos
A few months ago Brent Yorgey complained about a certain class of tutorials which present monads by explaining how monads are like burritos. At first I thought the choice of burritos was only a...
View ArticleA monad for probability and provenance
I don't quite remember how I arrived at this, but it occurred to me last week that probability distributions form a monad. This is the first time I've invented a new monad that I hadn't seen before;...
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