January 2015 - mathfun@mailman.xmission.com

Re: [math-fun] Fwd: Nice Fibonacci stuff from Edmark
by Bill Gosper 19 Jan '15

19 Jan '15

Holy cow, it's gorgeous at VLC default speed! With my Firefox and default download player, the frames aren't even in correct time order! Apologies, John, for even imagining that you would deliberately perpetrate such a crock. --rwg If you download this clip (using DownloadHelper addon) & play it back using the VLC player, you can adjust the speed of playback using the "[" and "]" keys. "Jerkiness" is often caused by frames being dropped because the computer can't decode them fast enough to play these frames "on time". If your computer isn't capable of running the video at full speed, then perhaps it will run the video at 60% of full speed, in which case "jerkiness" should disappear. Note that there may be jerkiness anyway due to "beating" of the speed of movement of the items being rotated in the video compared with the frame rate of the video itself. All that having been said, there is some "jerkiness" in this particular video which remains even after it has been slowed down to 20%, so whoever made the video inadvertently dropped some frames along the way -- perhaps by converting to/from video/TV frame rates (video is 29.97 in US, 25 in Europe; movies are 24fps in most cases). Some of the worst of these jerkiness artifacts are caused by conversion of "progressive" to/from "interlaced" video using "3-2 pulldown". http://en.wikipedia.org/wiki/Three-two_pull_down Perhaps Vimeo themselves transcoded the movie & introduced these artifacts. At 09:18 AM 1/19/2015, John Edmark wrote: Without seeing what you're seeing It's very hard to know whether the jerkiness is intrinsic to the video. May be some compression artifacts. On 1/19/15 12:39 AM, Bill Gosper wrote: I downloaded it. Jerkiness now looks intentionally "artsy", like timelapsed plant growth. --rwg ---------- Forwarded message ---------- From: *Jon Ziegler* <jonathan.zh(a)gmail.com <mailto:jonathan.zh@gmail.com>> Date: Mon, Jan 19, 2015 at 12:26 AM Subject: Re: Nice Fibonacci stuff from Edmark To: Julian Ziegler Hunts <julianj.zh(a)gmail.com <mailto:julianj.zh@gmail.com>> Cc: Bill Gosper <billgosper(a)gmail.com <mailto:billgosper@gmail.com>>, Neil Bickford <techie314(a)gmail.com <mailto:techie314@gmail.com>> Well, y'all ought to tell him you like it. Bill, I'm happy for you to post to math-fun if you think folks will be interested. (JZ) On Mon, Jan 19, 2015 at 12:23 AM, Julian Ziegler Hunts <julianj.zh(a)gmail.com <mailto:julianj.zh@gmail.com>> wrote: Nor me. It's related to the Fibonacci stuff he was doing before, certainly. Very nice (and not jerky for me). Julian On Mon, Jan 19, 2015 at 12:38 AM, Bill Gosper <billgosper(a)gmail.com <mailto:billgosper@gmail.com>> wrote: Whoa, not me! Tell math-fun. (But my playback, at least, is awfully jerky.) --Bill On Sun, Jan 18, 2015 at 1:15 PM, Jon Ziegler <jonathan.zh(a)gmail.com <mailto:jonathan.zh@gmail.com>> wrote: Hi Julian, Bill, Neil, This stuff from Edmark is pretty nice: http://www.theverge.com/2015/1/18/7749771/watch-3d-printed-objects-turn-int… Any of you help him out with it? Regards, Jon -- John Edmark Lecturer in Design Dept. of Art & Art History Stanford University 650.564.4884edmark(a)stanford.eduwww.JohnEdmark.com

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[math-fun] Fwd: Nice Fibonacci stuff from Edmark
by Bill Gosper 19 Jan '15

19 Jan '15

I downloaded it. Jerkiness now looks intentionally "artsy", like timelapsed plant growth. --rwg ---------- Forwarded message ---------- From: Jon Ziegler <jonathan.zh(a)gmail.com> Date: Mon, Jan 19, 2015 at 12:26 AM Subject: Re: Nice Fibonacci stuff from Edmark To: Julian Ziegler Hunts <julianj.zh(a)gmail.com> Cc: Bill Gosper <billgosper(a)gmail.com>, Neil Bickford <techie314(a)gmail.com> Well, y'all ought to tell him you like it. Bill, I'm happy for you to post to math-fun if you think folks will be interested. (JZ) On Mon, Jan 19, 2015 at 12:23 AM, Julian Ziegler Hunts <julianj.zh(a)gmail.com > wrote: > Nor me. It's related to the Fibonacci stuff he was doing before, > certainly. Very nice (and not jerky for me). > > Julian > > On Mon, Jan 19, 2015 at 12:38 AM, Bill Gosper <billgosper(a)gmail.com> > wrote: > >> Whoa, not me! Tell math-fun. (But my playback, at least, is awfully >> jerky.) >> --Bill >> >> On Sun, Jan 18, 2015 at 1:15 PM, Jon Ziegler <jonathan.zh(a)gmail.com> >> wrote: >> >>> Hi Julian, Bill, Neil, >>> >>> This stuff from Edmark is pretty nice: >>> >>> http://www.theverge.com/2015/1/18/7749771/watch-3d-printed-objects-turn-int… >>> >>> Any of you help him out with it? >>> >>> Regards, >>> Jon >>> >> >> >

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[math-fun] We've lost the world's most formidable q-slinger.
by Bill Gosper 19 Jan '15

19 Jan '15

Mizan Rahman, co-author of http://books.google.com/books/about/Basic_Hypergeometric_Series.html?id=Ptu… No matter how hard I twisted my q-hypergeometric matrices, he was impossible to stump, conjuring a derivation from his (and George's) justly famous book. --Bill Gosper ---------- Forwarded message ---------- From: Richard Askey <askey(a)math.wisc.edu> Date: Mon, Jan 19, 2015 at 8:25 AM Subject: *Mizan Rahman* To: billgosper(a)gmail.com Dear Bill, Here is some sad news. Dick ----- Forwarded message from Mourad Ismail <mourad.eh.ismail(a)gmail.com> ----- Date: Sat, 17 Jan 2015 20:50:48 -0500 From: Mourad Ismail <mourad.eh.ismail(a)gmail.com> Subject: Re: [ Fwd: Prof. Rahman] To: Martin Muldoon <muldoon(a)yorku.ca> Cc: Tom Koornwinder <T.H.Koornwinder(a)uva.nl>, Erik Koelink < e.koelink(a)math.ru.nl>, Richard Askey <askey(a)math.wisc.edu>, Dennis Stanton < stanton(a)math.umn.edu>, Denise Marks <kramerfan2fla(a)hotmail.com>, GEORGE E ANDREWS <gea1(a)psu.edu>, George G <george(a)math.northwestern.edu>, Christian Berg <BERG(a)math.ku.dk>, berndt(a)math.uiuc.edu Dear Martin, Thanks for confirming that Mizan Rahman passed away. I found an interesting about Mizan which may be used to write about him in the Newsletter of the SIAM activity group. It is on: http://biggani.org/?p=1019 Best regards Mourad On Sat, Jan 17, 2015 at 7:16 PM, Martin Muldoon <muldoon(a)yorku.ca> wrote: Mourad, Tom: > I did not find anything in regular searches, but > finally went to Facebook and, sadly, confirmed the passing of Mizan. > > www.facebook.com/MizanRahmanCanada > > If you click in the black area at the top you can read the attached. > He gave a speech in Toronto as recently as December 21, 2014. > > https://www.youtube.com/watch?v=Wy3lHphJG3s > > (mostly in Bengali with a few sentences in English) > > Martin > > > > > -- Mourad Ismail Professor of Mathematics University of Central Florida Tel: 407 823 2924 ----- End forwarded message ----- Richard Askey Dept of Mathematics Univ. of Wisconsin-Madison askey(a)math.wisc.edu 608-233-7900

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[math-fun] Chess variant
by James Propp 16 Jan '15

16 Jan '15

Has anyone proposed (and is there a name for) a variant of chess in which each player proposes two possible moves (s)he could make and the other player decides which of the two will be played? Jim Propp

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[math-fun] Models of the hyperbolic plane
by Mike Stay 14 Jan '15

14 Jan '15

Suppose we have the hyperboloid t^2 - x^2 - y^2 = 1. We get the Beltrami-Klein disk model of the plane by placing our eye at the origin and tracing what we see on the plane t=1. In this model, geodesics are straight lines, but angles aren't preserved. We get the Poincare disk model of the plane by taking one step back, placing our eye at t=-1 and tracing what we see on the plane t=0. In this model, geodesics are arcs of circles intersecting the boundary of the disk at right angles and angles are preserved. Clearly we can continue stepping backwards; what happens if we place our eye at t=-2 and draw what we see on the plane t=-1? Does it have any nice properties? Is there a limiting model? Does it have any nice properties? -- Mike Stay - metaweta(a)gmail.com http://www.cs.auckland.ac.nz/~mike http://reperiendi.wordpress.com

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[math-fun] Edmund Harriss's fractal spiral - and algebraic numbers
by Alex Bellos 14 Jan '15

14 Jan '15

http://www.theguardian.com/science/alexs-adventures-in-numberland/2015/jan/… <http://www.theguardian.com/science/alexs-adventures-in-numberland/2015/jan/…>

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[math-fun] Corey strikes again
by Bill Gosper 13 Jan '15

13 Jan '15

In[39]:= PolyhedronData["PentagonalCupola", "SurfaceArea"] Out[39]= 1/4 (20 + Sqrt[10 (80 + 31 Sqrt[5] + Sqrt[2175 + 930 Sqrt[5]])]) (*Depth 3. Probably lifted from http://en.wikipedia.org/wiki/Pentagonal_cupola*) In[40]:= Expand[RationalizeDenominator[Strad[%]]] Out[40]= 5 + (5 Sqrt[3])/4 + 1/4 5^(3/4) Sqrt[62 + 29 Sqrt[5]] (*Depth 2*) In[41]:= MinimalPolynomial[% - %%] Out[41]= #1 & Similarly for PolyhedronData["PentagonalGyrobicupola", "SurfaceArea"] (the dual of the (disappointingly squat) rhombic icosahedron) Something I didn't know: "The rhombic triacontahedron is also interesting in that its vertices include the arrangement of all the platonic solids <http://en.wikipedia.org/wiki/Platonic_solids>. It contains ten tetrahedrons <http://en.wikipedia.org/wiki/Tetrahedron>, five hexahedrons <http://en.wikipedia.org/wiki/Cube>, five octahedrons <http://en.wikipedia.org/wiki/Octahedron>, an icosahedron <http://en.wikipedia.org/wiki/Icosahedron> and a dodecahedron <http://en.wikipedia.org/wiki/Dodecahedron>." --rwg

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[math-fun] Math jam
by Stuart Anderson 12 Jan '15

12 Jan '15

A link to the 2014 Math Jam in Staffordshire, with some papers and slides ; http://www.mathsjam.com/conference/index.php?content=2014talks I particularly liked Geoffrey Morley's work on Squaring the Torus http://www.mathsjam.com/conference/talks/2014/GeoffreyMorley-Torus-Squaring… Stuart Anderson

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Re: [math-fun] RE Chess Problem (H Baker)
by Henry Baker 09 Jan '15

09 Jan '15

Yes, the problem I proposed was more of a puzzle than a game. I actually don't know if it can be solved. I don't know if it's possible to set up for a "massacre" wherein once pieces start to be taken, the _only_ moves allowed are captures until only the kings are left. I'm asking if a legal (if stupid) game of chess could progress without captures until a capture happens, after which only legal captures are allowed until only kings remain. I think that solving this would require hacking an existing chess program to first reject any captures, and then at some point, accept only captures. Since the capture game tree is substantially smaller than a normal game tree, it might actually be possible to store _every_ mini-massacre (sequences consisting of only captures), and hash it into a table. At 01:58 AM 1/9/2015, Guy Haworth wrote: >The two-phase chess 'game' seems to less than well defined, and - as far as it is defined - seems to be a puzzle rather than a game as there is only one results ... 'draw'. > >Losing Chess, which prioritises losing and capturing men, is perhaps the nearest in concept. > >There are various variants of it, but recent work on the mainline version of Losing Chess (ICGA Journal, Vol. 37-2 (2014) ) indicates that 1.e3 is a win for White. > >Guy

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[math-fun] The sign says LINE, not LINE SEGMENT
by Bill Gosper 09 Jan '15

09 Jan '15

But in an uncharacteristic spasm of rebelliousness, I exited my vehicle and took this picture anyway. gosper.org/IMG_0298.JPG "But officer, the Universe contains only a finite number of molecules of yellow paint." --rwg

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