The Universe of Discourse


Tue, 07 Apr 2020

Fern motif experts on the Internet

I live near Woodlands Cemetery and by far the largest monument there, a thirty-foot obelisk, belongs to Thomas W. Evans, who is an interesting person. In his life he was a world-famous dentist, whose clients included many crowned heads of Europe. He was born in Philadelphia, and land to the University of Pennsylvania to found a dental school, which to this day is located at the site of Evans’ former family home at 40th and Spruce Street.

A few days ago my family went to visit the cemetery and I insisted on visting the Evans memorial.

A young girl, seen from the back, is climbing a large stone
monument.  She is wearing black boots, blue jeans, and a black leather
jacket.  She is about six feet off the ground. Attached to the monument to her right is a
green copper plate that says  (among other things) ‘In memory of
DR. THOMAS WILLIAM EVANS’.  In the background is a tree, and other, smaller
monuments can be seen.

The obelisk has this interesting ornament:

Description below.

The thing around the middle is evidently a wreath of pine branches, but what is the thing in the middle? Some sort of leaf, or frond perhaps? Or is it a feather? If Evans had been a writer I would have assumed it was a quill pen, but he was a dentist. Thanks to the Wonders of the Internet, I was able to find out.

First I took the question to Reddit's /r/whatisthisthing forum. Reddit didn't have the answer, but Reddit user @hangeryyy had something better: they observed that there was a fad for fern decorations, called pteridomania, in the second half of the 19th century. Maybe the thing was a fern.

I was nerdsniped by pteridomania and found out that a book on pteridomania had been written by Dr. Sarah Whittingham, who goes by the encouraging Twitter name of @DrFrond.

Dr. Whittingham's opinion is that this is not a fern frond, but a palm frond. The question has been answered to my full and complete satisfaction.

My thanks to Dr. Whittingham, @hangeryyy, and the /r/whatisthisthing community.


[Other articles in category /art] permanent link

Mon, 06 Apr 2020

Anglo-Saxon and Hawai‘ian Wikipedias

Yesterday browsing the list of Wikipedias I learned there is an Anglo-Saxon Wikipedia. This seems really strange to me for several reasons: Who is writing it? And why?

And there is a vocabulary problem. Not just because Anglo-Saxon is dead, and one wouldn't expect it to have any words for anything not invented in the last 900 years or so. But also, there are very few extant Anglo-Saxon manuscripts, so we don't have a lot of vocabulary, even for things that had been invented 900 years ago.

Helene Hanff said:

I have these guilts about never having read Chaucer but I was talked out of learning Early Anglo-Saxon / Middle English by a friend who had to take it for her Ph.D. They told her to write an essay in Early Anglo-Saxon on any-subject-of-her-own-choosing. “Which is all very well,” she said bitterly, “but the only essay subject you can find enough Early Anglo-Saxon words for is ‘How to Slaughter a Thousand Men in a Mead Hall’.”

I don't read Anglo-Saxon but if you want to investigate, you might look at the Anglo-Saxon article about the Maybach Exelero (a hēahfremmende sportƿægn), Barack Obama, or taekwondo. I am pre-committing to not getting sucked into this, but sportƿægn is evidently intended to mean “sportscar” (the ƿ is an obsolete letter called wynn and is approximately a W, so that ƿægn is “wagon”) and I think that fremmende is “foreign” and hēah is something like "high" or "very". But I'm really not sure.

Anyway Wikipedia reports that the Anglo-Saxon Wikipedia has 3,197 articles (although most are very short) and around 30 active users. In contrast, the Hawai‘ian Wikipedia has 3,919 articles and only around 14 active users, and that is a language that people actually speak.


[Other articles in category /lang] permanent link

Caricatures of Nazis and the number four in Russian

[ Warning: this article is kinda all over the place. ]

I was looking at this awesome poster of D. Moor (Д. Моор), one of Russia's most famous political poster artists:

A Soviet propaganda poster, black,
with the foreground in yellowish-beige and a border of the same
color.  It depicts caricatures of the faces of Himmler, Göring,
Hitler, and Goebbels, labeled on the left with their names in
Russian.  Each name begins with the Russian letter Г, which is shaped
like an upside-down letter L.  Further description is below.

(original source at Artchive.RU)

This is interesting for a couple of reasons. First, in Russian, “Himmler”, “Göring”, “Hitler”, and “Goebbels” all begin with the same letter, ‘Г’, which is homologous to ‘G’. (Similarly, Harry Potter in Russian is Га́рри, ‘Garri’.)

I also love the pictures, and especially Goebbels. These four men were so ugly, each in his own distinctively loathsome way. The artist has done such a marvelous job of depicting them, highlighting their various hideousness. It's exaggerated, and yet not unfair, these are really good likenesses! It's as if D. Moor had drawn a map of all the ways in which these men were ugly.

My all-time favorite depiction of Goebbels is this one, by Boris Yefimov (Бори́с Ефи́мов):

A poster in black, blue, yellow, and muddy green, depicting
Goebbels as a hideous mashup with
Mickey Mouse. His tail divides into four at the end and is shaped like
a swastika.  His yellow-clived hands are balled into fists and spittle
is flying from his mouth. The poster is captioned (in English) at the top: “WHAT
IS AN ‘ARYAN’?  He is HANDSOME” and at the bottom “AS GOEBBELS”.

For comparison, here's the actual Goebbels:

Actual archival photograph of Goebbels, in right profile, just
like Mickey Mouse Goebbels in the previous picture, but from the chest
up.  His mouth is
closed and he is wearing a wool suit, white shirt with collar, and a
wide necktie.

Looking at pictures of Goebbels, I had often thought “That is one ugly guy,” but never been able to put my finger on what specifically was wrong with his face. But since seeing the Efimov picture, I have never been able to look at a picture of Goebbels without thinking of a rat. D. Moor has also drawn Goebbels as a tiny rat, scurrying around the baseboards of his poster.

Anyway, that was not what I had planned to write about. The right-hand side of D. Moor's poster imagines the initial ‘Г’ of the four Nazis’ names as the four bent arms of the swastika. The captions underneath mean “first Г”, “second Г” and so on.

[ Addendum: Darrin Edwards explains the meaning here that had escaped me:

One of the Russian words for shit is "govno" (говно). A euphemism for this is to just use the initial g; so "something na g" is roughly equivalent to saying "a crappy something". So the title "vse na g" (all on g) is literally "they all start with g" but pretty blatantly means "they're all crap" or "what a bunch of crap". I believe the trick of constructing the swastika out of four g's is meant to extend this association from the four men to the entire movement…

Thank you, M. Edwards! ]

Looking at the fourth one, четвертое /chetvyertoye/, I had a sudden brainwave. “Aha,” I thought, “I bet this is akin to Greek “tetra”, and the /t/ turned into /ch/ in Russian.”

Well, now that I'm writing it down it doesn't seem that exciting. I now remember that all the other Russian number words are clearly derived from PIE just as Greek, Latin, and German are:

English German Latin Greek Russian
one ein unum εἷς (eis) оди́н (odeen)
two zwei duo δύο (dyo) два (dva)
three drei trēs τρεῖς (treis) три (tri)
four vier quattuor τέτταρες (tettares) четы́ре (chyetirye)
five fünf quinque πέντε (pente) пять (pyat’)

In Latin that /t/ turned into a /k/ and we get /quadra/ instead of /tetra/. The Russian Ч /ch/ is more like a /t/ than it is like a /k/.

The change from /t/ to /f/ in English and /v/ in German is a bit weird. (The Big Dictionary says it “presents anomalies of which the explanation is still disputed”.) The change from the /p/ of ‘pente’ to the /f/ of ‘five’ is much more typical. (Consider Latin ‘pater’, ‘piscum’, ‘ped’ and the corresponding English ‘father’, ‘fish’, ‘foot’.) This is called Grimm's Law, yeah, after that Grimm.

The change from /q/ in quinque to /p/ in pente is also not unusual. (The ancestral form in PIE is believed to have been more like the /q/.) There's a classification of Celtic lanugages into P-Celtic and Q-Celtic that's similar, exemplified by the change from the Irish patronymic prefix Mac- into the Welsh patronymic map or ap.

I could probably write a whole article comparing the numbers from one to ten in these languages. (And Sanskrit. Wouldn't want to leave out Sanskrit.) The line for ‘two’ would be a great place to begin because all those words are basically the same, with only minor and typical variations in the spelling and pronunciation. Maybe someday.


[Other articles in category /lang/etym] permanent link

Sun, 05 Apr 2020

Screensharing your talk slides is skeuomorphic

Back when the Web was much newer, and people hadn't really figured it out yet, there was an attempt to bring a dictionary to the web. Like a paper dictionary, its text was set in a barely-readable tiny font, and there were page breaks in arbitrary places. That is a skeuomorph: it's an incidental feature of an object that persists even in a new medium where the incidental feature no longer makes sense.

Anyway, I was scheduled to give a talk to the local Linux user group last week, and because of current conditions we tried doing it as a videoconference. I thought this went well!

We used Jitsi Meet, which I thought worked quite well, and which I recommend.

The usual procedure is for the speaker to have some sort of presentation materials, anachronistically called “slides”, which they display one at a time to the audience. In the Victorian age these were glass plates, and the image was projected on a screen with a slide projector. Later developments replaced the glass with celluloid or other transparent plastic, and then with digital projectors. In videoconferences, the slides are presented by displaying them on the speaker's screen, and then sharing the screen image to the audience.

This last development is skeuomorphic. When the audience is together in a big room, it might make sense to project the slide images on a shared screen. But when everyone is looking at the talk on their own separate screen anyway, why make them all use the exact same copy?

Instead, I published the slides on my website ahead of time, and sent the link to the attendees. They had the option to follow along on the web site, or to download a copy and follow along in their own local copy.

This has several advantages:

  1. Each audience person can adjust the monitor size, font size, colors to suit their own viewing preferences.

    With the screenshare, everyone is stuck with whatever I have chosen. If my font is too small for one person to read, they are out of luck.

  2. The audience can see the speaker. Instead of using my outgoing video feed to share the slides, I could share my face as I spoke. I'm not sure how common this is, but I hate attending lectures given by disembodied voices. And I hate even more being the disembodied voice. Giving a talk to people I can't see is creepy. My one condition to the Linux people was that I had to be able to see at least part of the audience.

  3. With the slides under their control, audience members can go back to refer to earlier material, or skip ahead if they want. Haven't you had the experience of having the presenter skip ahead to the next slide before you had finished reading the one you were looking at? With this technique, that can't happen.

Some co-workers suggested the drawback that it might be annoying to try to stay synchronized with the speaker. It didn't take me long to get in the habit of saying “Next slide, #18” or whatever as I moved through the talk. If you try this, be sure to put numbers on the slides! (This is a good practice anyway, I have found.) I don't know if my audience found it annoying.

The whole idea only works if you can be sure that everyone will have suitable display software for your presentation materials. If you require WalSoft AwesomePresent version 18.3, it will be a problem. But for the past 25 years I have made my presentation materials in HTML, so this wasn't an issue.

If you're giving a talk over videoconference, consider trying this technique.

[ Addendum: I should write an article about all the many ways in which the HTML has been a good choice. ]


[Other articles in category /talk] permanent link

Fri, 27 Mar 2020

Pauli chess

Last week Pierre-Françoys Brousseau and I invented a nice chess variant that I've never seen before. The main idea is: two pieces can be on the same square. Sometimes when you try to make a drasatic change to the rules, what you get fails completely. This one seemed to work okay. We played a game and it was fun.

Specfically, our rules say:

  1. All pieces move and capture the same as in standard chess, except:

  2. Up to two pieces may occupy the same square.

  3. A piece may move into an occupied square, but not through it.

  4. A piece moving into a square occupied by a piece of the opposite color has the option to capture it or to share the square.

  5. Pieces of opposite colors sharing a square do not threaten one another.

  6. A piece moving into a square occupied by two pieces of the opposite color may capture either, but not both.

  7. Castling is permitted, but only under the same circumstances as standard chess. Pieces moved during castling must move to empty squares.

Miscellaneous notes

Pierre-Françoys says he wishes that more than two pieces could share a square. I think it could be confusing. (Also, with the chess set we had, more than two did not really fit within the physical confines of the squares.)

Similarly, I proposed the castling rule because I thought it would be less confusing. And I did not like the idea that you could castle on the first move of the game.

The role of pawns is very different than in standard chess. In this variant, you cannot stop a pawn from advancing by blocking it with another pawn.

Usually when you have the chance to capture an enemy piece that is alone on its square you will want to do that, rather than move your own piece into its square to share space. But it is not hard to imagine that in rare circumstances you might want to pick a nonviolent approach, perhaps to avoid a stalemate.

Some discussion of similar variants is on Chess Stack Exchange.

The name “Pauli Chess”, is inspired by the Pauli exclusion principle, which says that no more than two electrons can occupy the same atomic orbital.


[Other articles in category /games] permanent link

Tue, 24 Mar 2020

git log --author=... confused me

Today I was looking for recent commits by co worker Fred Flooney, address fflooney@example.com, so I did

    git log --author=ffloo

but nothing came up. I couldn't remember if --author would do a substring search, so I tried

    git log --author=fflooney
    git log --author=fflooney@example.com

and still nothing came up. “Okay,” I said, “probably I have Fred's address wrong.” Then I did

    git log --format=%ae | grep ffloo

The --format=%ae means to just print out commit author email addresses, instead of the usual information. This command did produce many commits with the author address fflooney@example.com.

I changed this to

    git log --format='%H %ae' | grep ffloo

which also prints out the full hash of the matching commits. The first one was 542ab72c92c2692d223bfca4470cf2c0f2339441.

Then I had a perplexity. When I did

    git log -1 --format='%H %ae' 542ab72c92c2692d223bfca4470cf2c0f2339441

it told me the author email address was fflooney@example.com. But when I did

    git show 542ab72c92c2692d223bfca4470cf2c0f2339441

the address displayed was fredf@example.com.

The answer is, the repository might have a file in its root named .mailmap that says “If you see this name and address, pretend you saw this other name and address instead.” Some of the commits really had been created with the address I was looking for, fflooney. But the .mailmap said that the canonical version of that address was fredf@. Nearly all Git operations use the canonical address. The git-log --author option searches the canonical address, and git-show and git-log, by default, display the canonical address.

But my --format=%ae overrides the default behavior; %ae explicitly requests the actual address. To display the canonical address, I should have used --format=%aE instead.

Also, I learned that --author= does not only a substring search but a regex search. I asked it for --author=d* and was puzzled when it produced commits written by people with no d. This is a beginner mistake: d* matches zero or more instances of d, and every name contains zero or more instances of d. (I had thought that the * would be like a shell glob.)

Also, I learned that --author=d+ matches only authors that contain the literal characters d+. If you want the + to mean “one or more” you need --author=d\+.

Thanks to Cees Hek, Gerald Burns, and Val Kalesnik for helping me get to the bottom of this.

The .mailmap thing is documented in git-check-mailmap.

[ Addendum: I could also have used git-log --no-use-mailmap ..., had I known about this beforehand. ]


[Other articles in category /prog] permanent link

Sun, 16 Feb 2020

Midichlorians

Over on the other blog I said “Midichlorians predated The Phantom Menace.” No, the bacterium was named years after the movie was released.

Thanks to Eyal Joseph Minsky-Fenick and Shreevatsa R. for (almost simultaneously) pointing out this mistake.


[Other articles in category /oops] permanent link

Thu, 13 Feb 2020

Gentzen's rules for natural deduction

Here is Gerhard Gentzen's original statement of the rules of Natural Deduction (“ein Kalkül für ‘natürliche’, intuitionistische Herleitungen”):

Screencap
from Gentzen's 1934 paper, titled “Die Schlußfiguren-Schemata”.  The
table is laid out in three lines, with the rules for ‘and’ and ‘or’,
then the rules for ‘exists’ and “for all’, and then the rules for
‘implies’, ‘not’, and ‘false’.  The variable names are written in
old-style German black-letter font, but otherwise the presentation is
almost identical to the modern form.

Natural deduction looks pretty much exactly the same as it does today, although the symbols are a little different. But only a little! Gentzen has not yet invented !!\land!! for logical and, and is still using !!\&!!. But he has invented !!\forall!!. The style of the !!\lnot!! symbol is a little different from what we use now, and he has that tent thingy !!⋏!! where we would now use !!\bot!!. I suppose !!⋏!! didn't catch on because it looks too much like !!\land!!. (He similarly used !!⋎!! to mean !!\top!!, but as usual, that doesn't appear in the deduction rules.)

We still use Gentzen's system for naming the rules. The notations “UE” and “OB” for example, stand for “und-Einführung” and “oder-Beseitigung”, which mean “and-introduction” and “or-elimination”.

Gentzen says (footnote 4, page 178) that he got the !!\lor, \supset, \exists!! signs from Russell, but he didn't want to use Russell's signs !!\cdot, \equiv, \sim, ()!! because they already had other meanings in mathematics. He took the !!\&!! from Hilbert, but Gentzen disliked his other symbols. Gentzen objected especially to the “uncomfortable” overbar that Hilbert used to indicate negation (“[Es] stellt eine Abweichung von der linearen Anordnung der Zeichen dar”). He attributes his symbols for logical equivalence (!!\supset\subset!!) and negation to Heyting, and explains that his new !!\forall!! symbol is analogous to !!\exists!!. I find it remarkable how quickly this caught on. Gentzen also later replaced !!\&!! with !!\land!!. Of the rest, the only one that didn't stick was !!\supset\subset!! in place of !!\equiv!!. But !!\equiv!! is much less important than the others, being merely an abbreviation.

Gentzen died at age 35, a casualty of the World War.

Source: Gerhard Gentzen, “Untersuchungen über das logische Schließen I”, pp. 176–210 Mathematische Zeitschrift v. 39, Springer, 1935. The display above appears on page 186.

[ Addendum 20200214: Thanks to Andreas Fuchs for correcting my German grammar. ]


[Other articles in category /math/logic] permanent link

Thu, 06 Feb 2020

Major screwups in mathematics: example 3

[ Previously: “Cases in which some statement S was considered to be proved, and later turned out to be false”. ]

In 1905, Henri Lebesgue claimed to have proved that if !!B!! is a subset of !!\Bbb R^2!! with the Borel property, then its projection onto a line (the !!x!!-axis, say) is a Borel subset of the line. This is false. The mistake was apparently noticed some years later by Andrei Souslin. In 1912 Souslin and Luzin defined an analytic set as the projection of a Borel set. All Borel sets are analytic, but, contrary to Lebesgue's claim, the converse is false. These sets are counterexamples to the plausible-seeming conjecture that all measurable sets are Borel.

I would like to track down more details about this. This Math Overflow post summarizes Lebesgue's error:

It came down to his claim that if !!{A_n}!! is a decreasing sequence of subsets in the plane with intersection !!A!!, the the projected sets in the line intersect to the projection of !!A!!. Of course this is nonsense. Lebesgue knew projection didn't commute with countable intersections, but apparently thought that by requiring the sets to be decreasing this would work.


[Other articles in category /math] permanent link

Tue, 28 Jan 2020

James Blaine keeps turning up

Today I learned that James Blaine (U.S. Speaker of the House, senator, perennial presidential candidate, and Secretary of State under Presidents Cleveland, Garfield, and Arthur; previously) was the namesake of the notorious “Blaine Amendments”. These are still an ongoing legal issue!

The Blaine Amendment was a proposed U.S. constitutional amendment rooted in anti-Catholic, anti-immigrant sentiment, at a time when the scary immigrant bogeymen were Irish and Italian Catholics.

The amendment would have prevented the U.S. federal government from providing aid to any educational institution with a religious affiliation; the specific intention was to make Catholic parochial schools ineligible for federal education funds. The federal amendment failed, but many states adopted it and still have it in their state constitutions.

Here we are 150 years later and this is still an issue! It was the subject of the 2017 Supreme Court case Trinity Lutheran Church of Columbia, Inc. v. Comer. My quick summary is:

  1. The Missouri state Department of Natural Resources had a program offering grants to licensed daycare facilities to resurface their playgrounds with shredded tires.

  2. In 2012, a daycare facility operated by Trinity Lutheran church ranked fifth out of 44 applicants according to the department’s criteria.

  3. 14 of the 44 applicants received grants, but Trinity Lutheran's daycare was denied, because the Missouri constitution has a Blaine Amendment.

  4. The Court found (7–2) that denying the grant to an otherwise qualified daycare just because of its religious affiliation was a violation of the Constitution's promises of free exercise of religion. (Full opinion)

It's interesting to me that now that Blaine is someone I recognize, he keeps turning up. He was really important, a major player in national politics for thirty years. But who remembers him now?


[Other articles in category /law] permanent link

Fri, 17 Jan 2020

Pylgremage of the Sowle

As Middle English goes, Pylgremage of the Sowle (unknown author, 1413) is much easier to read than Chaucer:

He hath iourneyed by the perylous pas of Pryde, by the malycious montayne of Wrethe and Enuye, he hath waltred hym self and wesshen in the lothely lake of cursyd Lechery, he hath ben encombred in the golf of Glotony. Also he hath mysgouerned hym in the contre of Couetyse, and often tyme taken his rest whan tyme was best to trauayle, slepyng and slomeryng in the bed of Slouthe.

I initially misread “Enuye” as “ennui”, understanding it as sloth. But when sloth showed up at the end, I realized that it was simpler than I thought, it's just “envy”.


[Other articles in category /book] permanent link

Thu, 16 Jan 2020

A serious proposal to exploit the loophole in the U.S. Constitution

In 2007 I described an impractical scheme to turn the U.S. into a dictatorship, or to make any other desired change to the Constitution, by having Congress admit a large number of very small states, which could then ratify any constitutional amendments deemed desirable.

An anonymous writer (probably a third-year law student) has independently discovered my scheme, and has proposed it as a way to “fix” the problems that they perceive with the current political and electoral structure. The proposal has been published in the Harvard Law Review in an article that does not appear to be an April Fools’ prank.

The article points out that admission of new states has sometimes been done as a political hack. It says:

Republicans in Congress were worried about Lincoln’s reelection chances and short the votes necessary to pass the Thirteenth Amendment. So notwithstanding the traditional population requirements for statehood, they turned the territory of Nevada — population 6,857 — into a state, adding Republican votes to Congress and the Electoral College.

Specifically, the proposal is that the new states should be allocated out of territory currently in the District of Columbia (which will help ensure that they are politically aligned in the way the author prefers), and that a suitable number of new states might be one hundred and twenty-seven.


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