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# Posts

### October 30, 2014

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On Chris Graney’s recent guest post I linked to an earlier guest post that he had written about the Danish Renaissance astronomer Tycho Brahe and one of the new readers, that this link attracted, posted a question that I seem … Continue reading →
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The eloquently excellent Elegant Fowl (aka Pete Langman @elegantfowl) just drew my attention to a piece of high-grade seventeenth-century history of science rubbish on the website of my favourite newspaper The Guardian. In the books section a certain Ian Mortimer … Continue reading →
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Since tomorrow is Halloween, I thought we would address some Halloween […]

### October 29, 2014

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Josh Parsons (Oxford) has written a widely discussed post on "The LaTeX cargo cult," explaining why he discourages philosophy students from using LaTeX.  He makes some interesting points.  But what he has left out is the overarching principle that you should simply always use the best tool for the purpose at hand - and "best" should take into account lots of things: cost (in money and time you need to invest to become proficient in the use of the tool), ease of use, functionality, and the […]
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Josh Parsons (Oxford) has written a widely discussed post on "The LaTeX cargo cult," explaining why he discourages philosophy students from using LaTeX.  He makes some interesting points.  But what he has left out is the overarching principle that you should simply always use the best tool for the purpose at hand - and "best" should take into account lots of things: cost (in money and time you need to invest to become proficient in the use of the tool), ease of use, functionality, and the […]
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Ieri siamo andati al concerto Stefano Bollani Piano Solo di Enjoy JazzBollani era in grande forma: improvvisazione e umorismo a livelli altissimi. Interazione con il pubblico come al solito. Stavolta il tormentone sono stati i colpi di tosse del pubblico ripresi da lui e incastrati nei suoi pezzi.Immancabile e irresistibile il bis con lista di autori e canzoni chieste al pubblico. Brillante quasi come quella del concerto di Francoforte.
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Octothorpe: In the 1960's when Bell Telephone added two new buttons for push […]

### October 28, 2014

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A recent blog post on Yovisto repeats a very widespread myth concerning Copernicus, his De revolutionibus and the calendar reform of 1582. This particular myth is so prevalent that I have no illusions about stamping it out but as a … Continue reading →
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Ho appena letto su Qfwwwfq questo interessante articolo sul giovane Leopardi: IL GIOVANE METAFISICO. Ne rilancio qualche passaggio.«Nelle dissertazioni il "giovane favoloso" sostiene una serie di luoghi comuni della metafisica tradizionale che di lì a poco abbandonerà come fossero favole infantili, e si tratta esattamente di alcuni di quei luoghi comuni che modellano ancora oggi le vie neurali di gran parte dell'umanità, nonché di molti di quei filosofi idealisti e […]
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Obelus:  The symbol "÷" which is used to indicate the operation of […]
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I had a wonderful opportunity yesterday to meet with and share a meal with Pat Ballew.  Pat and I have been friend for a while, but this is the first time we had a chance to meet.Pat is a retired math teacher and runs his website kind of like I do.  He puts stuff on his website (PBallew.blogspot.com) that interests him.  He has a little math and math trivia, a lot of math and science history and a link to to his website "MathWords" (http://www.pballew.net/etyindex.html) which […]

### October 27, 2014

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At this year's Vienna Summer of Logic the organizers did something I haven't seen done before, and which I think should be emulated: over the course of the two weeks that 2,400 logicians were gathered in Vienna, they organized a Logic Lounge in seven instalments.  For an hour each, one or more conference participants engaged in a moderated conversation in front of a general audience in a café near the conference venue. The moderators were well-prepared, and the discussants all had […]
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- Ritmi irrazionali!? Ma che significa? Come fanno a essere irrazionali i ritmi? Io ho sempre visto delle frazioni all'inizio delle partiture. Tipo 2/4, 3/4, 4/4. Non sono quelle che stabiliscono il ritmo del pezzo? Che significa che il ritmo è irrazionale? Che invece di un 4/4 potrò avere un √2/4 o un π/4? Un po' difficile da contare no? Questa cosa mi puzza. Non è che mi stai per raccontare cose simili alla musica spettrale o agli esperimenti con spettri […]
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Solutions to Friday's Quiz:1.  Panda.2.  Post Office.3.  None.  O […]

### October 26, 2014

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A Dozen, a Gross, and a Score,  plus three times the square root of four,  divided by seven,              plus five times eleven,  equals nine squared and not a bit more.    David

### October 25, 2014

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This problem is related to a broader problem known as “Squaring the Square” […]
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11 pieces are needed.  Other solutions are available, but none have less than 11 pieces.David

### October 24, 2014

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Da La Stampa del 18 settembre"Al termine di sette anni di scavi un gruppo del museo Yad VeShem di Gerusalemme ha ritrovato nel sottosuolo della Polonia una delle camere a gas del campo di sterminio di Sobibor contribuendo a portare alla luce un tassello della Shoah che i nazisti tentarono di occultare distruggendolo e piantandovi sopra nel 1943 un'intera foresta.David Silberkland, capo delle ricerche a Sobibor, ha lavorato sulla base dei frammenti di testimonianze dei pochissimi […]
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Mr. B’s “BRAIN-O” Quiz   Guaranteed to unclog clogged up […]

### October 23, 2014

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I am so sorry that I forgot Martin Gardner's birthday on October 21st.  He has been gone for a while now, but he would have been 100 years old this year.If you don't know his name, and you are interested in recreational mathematology you need to learn it.  Strickly speaking is is not a mathematician, he is a journalist.  But he has written more on the topic of mathematics (in particular recreational mathematics) than any mathematician I know of.Many of you have been his fans for […]
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Courses Logic I (Phil 279) Logic II (Phil 379) Logic III (Phil 479) Modal Logic (Phil 579.2/679.5) Nineteenth and Twentieth Century Analytic Philosophy (Phil 307) […]
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Sam Loyd produced this puzzle a while back, and it has become one his most famous puzzles:"For Christmas, Mrs. Potipher Perkins received a very pretty patchwork quilt constructed of 169 square pieces of silk material. The puzzle is to find the smallest number of square portions of which the quilt could be composed and show how they might be joined together. Or, to put it the reverse way, divide the quilt into as few square portions as possible by merely cutting the stitches."Warning: The […]

### October 22, 2014

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The integral z-squared dzFrom one to the cube root of threeTimes the cosineOf three pi over nineEquals log of the cube root of e.  David

### October 21, 2014

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One form of a paradox is a sentence that appears to contradict itself.  For example:“This sentence is false”If the sentence is true, then it has to be false (because that is what it says).If the sentence is false, then it has to be true (because is it false that “This sentence is false.”).It can also apply to mathematical statements, such as Richards Paradox.Clearly there are integers so huge they can’t be described in fewer than 22 syllables. Put them all in a big pile and […]
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The Prof is back. A couple of years back Professor Christopher M. Graney, known to his friends as Chris, wrote a highly informative guest post for The Renaissance Mathematicus defending the honour of Tyco Brahe against his ignorant modern critics. In the mean time … Continue reading →
Editor's Pick
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A dire il vero, qualche volta l'esigenza della virgola interrogativa l'ho avuta. E forse pure del punto ironizzante. Altrimenti uno è costretto a usare sempre le emoticone che, in alcuni contesti, non sono molto appropriate. Che ne dite? L'esistenza di segni di punteggiatura che ignoravo l'ho scoperta leggendo l'interessante articolo "La mia Giornata proGrammatica", in cui Licia Corbolante racconta la sua esperienza di esperta linguistica e "testimone di buona lingua" presso l’IIS Paolo […]
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There's a discussion going on at the Foundations of Mathematics mailing list about the purpose and value, actual and potential, for formalized proofs in mathematics.  Harvey Friedman asked Jeremy Avigad to comment; he sent this super-useful list of references, republished here with his approval. John Harrison and I recently wrote a survey on formalized mathematics, for computer scientists: Jeremy Avigad, John Harrison, 2014, "Formally verified mathematics." Communications of the ACM 57: […]

### October 20, 2014

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Just found out that Edward Nelson died last month. http://www.princeton.edu/main/news/archive/S41/11/36I14/index.xml http://en.wikipedia.org/wiki/Edward_Nelson AddThis:
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1.  Dog.2.  Add a slash to turn a + sign into a 4: 5 + 545 = 550.3.& […]
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3.14159265358979323846264338327950288419716939937510…Well, the first digit is 3 – that’s prime.3.14159265358979323846264338327950288419716939937510…1 is not prime, 14 is not prime, 141 is not prime, 1415 is not prime, but 14159 is prime.3.14159265358979323846264338327950288419716939937510…2 is prime.3.14159265358979323846264338327950288419716939937510…6 is not prime, 65 is not prime, but 653 is prime.3.14159265358979323846264338327950288419716939937510…5 is […]