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Thu, 22 Jul 2021 Take some real number !!\alpha!! and let its convergents be !!c_0, c_1, c_2, \ldots!!. Now consider the convergents of !!2\alpha!!. Sometimes they will include !!2c_0, 2c_1, 2c_2, \ldots!!, sometimes only some of these. For example, the convergents of !!\pi!! and !!2\pi!! are $$ \begin{array}{rlc}
\pi & \approx &
\color{darkblue}{3},&&& \color{darkblue}{\frac{22}{7}}, &
\color{darkblue}{\frac{333}{106}}, && \color{darkblue}{\frac{355}{113}}, &
\color{darkblue}{\frac{103993}{33102}}, &&
\frac{104348}{33215}, &
\color{darkblue}{\frac{208341}{66317}}, &
\ldots \\
2\pi & \approx &
\color{darkblue}{6}, & \frac{19}{3}, & \frac{25}{4}, & \color{darkblue}{\frac{44}{7}}, &
\color{darkblue}{\frac{333}{53}}, &
\frac{377}{60}, &
\color{darkblue}{\frac{710}{113}}, &
\color{darkblue}{\frac{103393}{16551}}, &
\frac{312689}{49766}, &&
\color{darkblue}{\frac{416682}{66317}}, &
\ldots
\end{array} Here are the analogous lists for !!\frac{1+\sqrt{5}}2!! and !!1+\sqrt5!!: $$ \begin{array}{rlc} \frac12{1+\sqrt{5}}& \approx & 1, & 2, & \color{darkblue}{\frac32}, & \frac53, & \frac85, & \color{darkblue}{\frac{13}8}, & \frac{21}{13}, & \frac{34}{21}, & \color{darkblue}{\frac{55}{34}}, & \frac{89}{55}, & \frac{144}{89}, & \color{darkblue}{\frac{233}{144}}, & \frac{377}{233}, &\frac{610}{377} , & \color{darkblue}{\frac{987}{610} }, & \ldots \\ 1+\sqrt{5} & \approx & & & \color{darkblue}{3}, &&& \color{darkblue}{\frac{13}4}, &&& \color{darkblue}{\frac{55}{17}}, &&& \color{darkblue}{\frac{233}{72}}, &&& \color{darkblue}{\frac{987}{305}}, & \ldots \end{array} $$ This time all the convergents in the second list are matched by convergents in the first list. The number !!\frac{1+\sqrt5}{2}!! is notorious because it's the real number whose convergents converge the most slowly. I'm surprised that !!1+\sqrt5!! converges so much more quickly; I would not have expected the factor of 2 to change the situation so drastically. I haven't thought about this at all yet, but it seems to me that a promising avenue would be to look at what Gosper's algorithm would do for the case !!x\mapsto 2x!! and see what simplifications can be done. This would probably produce some insight, and maybe a method for constructing a number !!\alpha!! so that all the convergents of !!2\alpha!! are twice those of !!\alpha!!. [Other articles in category /math] permanent link Fri, 09 Jul 2021
“Forensic” doesn't mean what I thought it did
Last week at work we released bad code, which had somehow survived multiple reviews. I was very interested in finding out how this happened, dug into the Git history to find out, and wrote a report. Originally I titled the report something like “Forensic analysis of Git history” (and one of my co-workers independently referred to the investigation as forensic) but then I realized I wasn't sure what “forensic” meant. I looked it up, and learned it was the wrong word. A forensic analysis is one performed in the service of a court or court case. “Forensic” itself is from Latin forum, which is a public assembly place where markets were held and court cases were heard. Forensic medicine is medicine in service of a court case, for example to determine a cause of death. For this reason it often refers to a postmortem examination, and I thought that “forensic” meant a postmortem or other retrospective analysis. That was the sense I intended it. But no. I had written a postmortem analysis, but not a forensic one. [Other articles in category /lang/etym] permanent link Thu, 08 Jul 2021
A simple dice-throwing game that seems hard to play
I ran into a fun math problem yesterday, easy to ask, easy to understand, but somewhat open-ended and seems to produce fairly complex behavior. It might be a good problem for a bright high school student to tinker with. Consider the following one-player game. You start with a total of n points. On each turn, you choose to throw either a four-, six-, or eight-sided die, and then subtract the number thrown from your point total. The game continues until your total reaches zero (and you win) or goes below zero (and you lose). This game seems surprisingly difficult to analyze. The computer analysis is quite easy, but what I mean is, if someone comes to you offering to pay you a dollar if you can win starting with !!n=9!! points, and it would be spoilsportish to say “just wait here for half an hour while I write this computer program”, what's your good move? Is there even a way to make an educated guess, short of doing a full analysis? The !!n≤4!! strategy is obvious, but even for !!n=5!! you need to start calculating: rolling the d4 is safe. Rolling the d6 gives you a chance of wiping out, but also a chance of winning instantly; is that an improvement? (Spoiler: it is, quite substantially so! Your chance of winning increases from !!36\%!! to !!40.7\%!!.) With the game as described, and optimal play, the probability of winning approaches !!45.66\%!! as the number of points increases, and the strategy is not simple: the best strategy for !!n≤20!! uses the d4 in 13 cases, the d6 in 4 cases, and the d8 in 3 cases: $$\begin{array}{rcl} n & \text{Best play} & \text{Win %} \\ \hline 1 & 4\quad & 25.00\% \\ 2 & 4\quad & 31.25 \\ 3 & 4\quad & 39.06 \\ 4 & 4\quad & 48.83 \\ \hline 5 & 6 & 40.69\% \\ 6 & 6 & 47.47 \\ 7 & 4\quad & 44.01 \\ 8 & \quad8 & 47.04 \\ \hline 9 & 4\quad & 44.80\% \\ 10 & 4\quad & 45.83 \\ 11 & 4\quad & 45.42 \\ 12 & 4\quad & 45.77 \\ \hline 13 & 6 & 45.48 \% \\ 14 & \quad8 & 45.73 \\ 15 & 4\quad & 45.60 \\ 16 & \quad8 & 45.71 \\ \hline 17 & 4\quad & 45.63 \% \\ 18 & 4\quad & 45.67 \\ 19 & 4\quad & 45.65 \\ 20 & 6 & 45.67 \end{array} $$ It seems fairly clear (and not hard to prove) that when the die with fewest sides has !!d!! sides, the good numbers of points are multiples of !!d!!, with !!kd+1!! somewhat worse, and then !!kd+2, kd+3, \ldots!! generally better and better to the next peak at !!kd+d!!. But there are exceptions: even if !!d!! is not the smallest die, if you have a !!d!!-sided die, it is good to have !!d!! points, and when you do you should roll the !!d!!-sided die. I did get a little more insight after making the chart above and seeing the 4-periodicity. In a comment on my Math SE post I observed:
The d4-d6-d8 case is unusually confusing, because for example it's not clear whether from 12 points you should throw d4, hoping to land on 8, or d6, hoping to land on 6. (I haven't checked but I imagine the two strategies perform almost equally well; similarly it probably doesn't matter much if you throw the d4 or the d6 first from !!n=10!!.) That the d6 is best for !!n=13!! is very surprising to me. Why !!45.66\%!!? I don't know. With only one die, the winning probability for large !!n!! converges to !!\frac2{n+1}!! which I imagine is a fairly straightforward calculation (but I have not done it). For more than one die, it seems much harder. Is there a way to estimate the winning probability for large !!n!!, given the list of dice? Actually yes, a little bit: the probability of winning with just a d4 is !!\frac 25!!, and the d6 and d8 can't hurt, so we know the chance of winning with all three dice available will be somewhat more than !!40\%!!, as it is. The value of larger dice falls off rapidly with the number of sides, so for example with d4+d6 the chance of winning increases from !!40\%!! to almost !!45\%!!, and adding the d8 only nudges this up to !!45.66\%!!. The probability of winning with a d2 is !!\frac 23!!, and if you have a d3 also the probability goes up to !!\frac 34!!, which seems simple enough, but if you add a d4 instead of the d3 instead it goes to !!68.965\%!!, whatever that is. And Dfan Schmidt tells me that d3 + d4 converges to !!\frac{512}{891}!!. I wrote it up for Math StackExchange but nobody has replied yet. Here's Python code to calculate the values. Enjoy. [ Addendum: Michael Lugo points out that the d2+d4 probability (“!!68.965\%!!, whatever that is”) is simply !!\frac{20}{29}!!, and gives some other similar results. One is that d3+d4+d5 has a winning probability of !!\frac{16}{27}!!; the small denominator is surprising. ] [Other articles in category /math] permanent link Wed, 07 Jul 2021Katara is interested in linguistics. When school was over for the year and she had time to think about things, I gave her all my old linguistics books. The other day for some reason I mentioned to her that I had known people who were engaged in formal research on the problem of how to get a computer to know what a pronoun referred to, and that this is very difficult. (I once had a co-worker who claimed that it was simple: the pronoun always refers back to the nearest noun. It wasn't hard to go back in his Slack history and find a counterexample he had uttered a few minutes before.) Today I wanted to tell Katara about dummy pronouns, which refer to nothing at all. I intended to send her the example from Wiktionary:
I started my message:
Then I realized I no longer needed the example. [Other articles in category /lang] permanent link Mon, 05 Jul 2021In English, this is called duckface: In German, I've learned, it's Schlauchbootlippen. Schlauch is “tube”. A Schlauchboot is a tube-boat — an inflatable rubber dingy. Schlauchbootlippen means dinghy-lips. [Other articles in category /lang/etym] permanent link Sun, 27 Jun 2021
Dogs that look like board games
In Korean, “바둑이” (/badugi/) is a common name for a spotted dog, especially a black-spotted dog. This is because “바둑” (/baduk/) is the native Korean name for the game of go, in which round black and white stones are placed on a board. In English, black-and-white spotted dogs are sometimes named “Checkers” for essentially the same reason. [Other articles in category /lang/etym] permanent link Mon, 19 Apr 2021Recently I've been complaining about unforced translation errors. ([1] [2]) Here's one I saw today: The translation was given as:
Now, the Russian text clearly says “beep-beep” (“бип-бип”), not “honk honk”. I could understand translating this as "honk honk" if "beep beep" were not a standard car sound in English. But English-speaking cars do say “beep beep”, so why change the original? (Also, a much smaller point: I have no objection to translating “Что за херня” as “what the fuck”. But why translate “Что за херня, Олег?” as “Oleg, what the fuck” instead of “What the fuck, Oleg”?) [ Addendum 20210420: Katara suggested that perhaps the original translator was simply unaware that Anglophone cars also “beep beep”. ] [Other articles in category /lang] permanent link Wed, 14 Apr 2021A couple of days ago I discussed the epithet “soup-guzzling pie-muncher”, which in the original Medieval Italian was brodaiuolo manicator di torte. I had compained that where most translations rendered the delightful word brodaiuolo as something like “soup-guzzler” or “broth-swiller”, Richard Aldington used the much less vivid “glutton”. A form of the word brodaiuolo appears in one other place in the Decameron, in the sixth story on the first day, also told by Emilia, who as you remember has nothing good to say about the clergy:
J. M. Rigg (1903), who had elsewhere translated brodaiuolo as “broth-guzzling”, this time went with “gluttony”:
G. H. McWilliam (1972) does at least imply the broth:
John Payne (1886):
Cormac Ó Cuilleanáin's revision of Payne (2004):
And what about Aldington (1930), who dropped the ball the other time and rendered brodaiuolo merely as “glutton”? Here he says:
Oh, Richard. I think you should have tried harder. [Other articles in category /lang] permanent link Mon, 12 Apr 2021A few months ago I was pondering what it might be like to be Donald Trump. Pretty fucking terrible, I imagine. What's it like, I wondered, to wake up every morning and know that every person in your life is only interested in what they can get from you, that your kids are eagerly waiting for you to die and get out of their way, and that there is nobody in the world who loves you? How do you get out of bed and face that bitter world? I don't know if I could do it. It doesn't get him off the hook for his terrible behavior, of course, but I do feel real pity for the man. It got me to thinking about another pitiable rich guy, Ebeneezer Scrooge. Scrooge in the end is redeemed when he is brought face to face with the fact that his situation is similar to Trump's. Who cares that Scrooge has died? Certainly not his former business associates, who discuss whether they will attend his funeral:
Later, the Spirit shows Scrooge the people who are selling the curtains stolen from his bed and the shirt stolen from his corpse, and Scrooge begs:
The Spirit complies, by finding a couple who had owed Scrooge money, and who will now, because he has died, have time to pay. I can easily replace Scrooge with Trump in any of these scenes, right up to the end of chapter 4. But Scrooge in the end is redeemed. He did once love a woman, although she left him. Scrooge did have friends, long ago. He did have a sister who loved him, and though she is gone her son Fred still wants to welcome him back into the family. Did Donald Trump ever have any of those things? [Other articles in category /book] permanent link The ten storytellers in The Decameron aren't all well-drawn or easy to tell apart. In the introduction of my favorite edition, the editor, Cormac Ó Cuilleanáin, says:
I agree, mostly. I can see Dioneo more clearly than Ó Cuilleanáin suggests. Dioneo reminds me of Roberto Benigni's Roman filthy-minded Roman taxi driver in Night on Earth. I also get a picture of Bocaccio's character Filostrato, who is a whiny emo poet boy who complains that he woman he was simping for got tired of him and dumped him for someone else:
When it's Filostrato's turn to choose the theme for the day's stories, he makes the others tell stories of ill-starred love with unhappy endings. They comply, but are relieved when it is over. (Dioneo, who is excused from the required themes, tells instead a farcical story of a woman who hides her secret lover in a chest after he unwittingly drinks powerful sedative.) Ah, but Emilia. None of the characters in the Decameron is impressed with the manners or morals of priests. But Emilia positively despises them. Her story on the third day is a good example. The protagonist, Tedaldo, is meeting his long-lost mistress Ermellina; she broke off the affair with him seven years ago on the advice of a friar who advised that she ought to remain faithful to her husband. Tedaldo is disguised as a friar himself, and argues that she should resume the affair. He begins by observing that modern friars can not always be trusted:
Modern friars, narrates Emilia, "strut about like peacocks" showing off their fine clothes. She goes on from there, complaining about friars' vanity, and greed, and lust, and hypocrisy, getting more and more worked up until you can imagine her frothing at the mouth. This goes on for about fifteen hundred words before she gets back to Tedaldo and Ermellina, just at the same time that I get around to what I actually meant to write about in this article: Emilia has Tedaldo belittle the specific friar who was the original cause of his troubles,
This was so delightful that I had to write a whole blog post just to show it to you. I look forward to calling other people soup-guzzling pie-munchers in the coming months. But, as with the earlier article about the two-bit huckster I had to look up the original Italian to see what it really said. And, as with the huckster, the answer was, this was pretty much what Bocaccio had originally written, which was:
Delightful! I love Bocaccio. While I was researching this article I ran into some other English translations of the phrase. The translation at Brown University's Decameron Web is by J.M. Rigg:
which I award full marks. The translation of John Payne has
and two revised versions of Payne, by Singleton and Ó Cuilleanáin, translate it similarly. But the translation of Richard Aldington only says:
which I find disappointing. I often wonder why translators opt to water down their translations like this. Why discard the vivid and specific soup and pie in favor of the abstract "fat-witted glutton"? What could possibly be the justification? Translators have a tough job. A mediocre translator will capture only the surface meaning and miss the subtle allusions, the wordplay, the connotations. But here, Aldington hasn't even captured the surface meaning! How hard is it to see torte and include pie in your translation somewhere? I can't believe that his omitting it was pure carelessness, only that Aldington thought that he was somehow improving on the original. But how, I can't imagine. Well, I can imagine a little. Translations can also be too literal. Let's consider the offensive Spanish epithet pendejo. Literally, this is a pubic hair. But to translate it in English as "pubic hair" would be a mistake, since English doesn't use that term in the same way. A better English translation is "asshole". This is anatomically illogical, but linguistically correct, because the metaphor in both languages has worn thin. When an anglophone hears someone called an “asshole” they don't normally imagine a literal anus, and I think similarly Spanish-speakers don't picture a literal pubic hair for pendejo. Brodaiuolo could be similar. Would a 14th-century Florentine, hearing brodaiuolo, picture a generic glutton, or would they imagine someone literally holding a soup bowl up to their face? We probably don't know. But I'm inclined to think that “soup-guzzler” is not too rich, because by this point in Emilia's rant we can almost see the little flecks of spittle flying out of here mouth. I'm offended by Aldington's omission of pie-munching. [ Addendum 20210414: More translations of brodaiuolo. ] [Other articles in category /book] permanent link Mon, 29 Mar 2021The King James Version of Job 19:26 says:
I find this mysterious for two reasons. First, I cannot understand the grammar. How is this supposed to be parsed? I can't come up with any plausible way to parse this so that it is grammatically correct. Second, how did the worms get in there? No other English translation mentions worms and they appear to be absent from the original Hebrew. Did the KJV writers mistranslate something? (Probably not, there is nothing in the original to mistranslate.) Or is it just an interpolation? Pretty ballsy, to decide that God left something out the first time around, but that you can correct His omission. [Other articles in category /book] permanent link Fri, 26 Mar 2021
Something I didn't know and I bet you didn't either
The Panama Canal has a loyalty program. If you're planning to ship at least 450,000 TEU per year, you can register in advance and get a discount on your tolls. [Other articles in category /misc] permanent link |