From: kirby urner
<kirby...@gmail.com>
To: mathf...@googlegroups.com
Sent: Fri, June 11, 2010 1:51:34 PM
Subject: Re: [Math 2.0] Re: Tessellations Again
On Fri, Jun 11, 2010 at 7:25 AM, Bradford Hansen-Smith
<
wholem...@sbcglobal.net> wrote:
> Kirby,
>
> As you stated....
>
>>Aristotle was right by the way, tetrahedra *do* fill
>>space. According to this recent source, he never
>>said "regular":
>
>> >
>> > "Which Tetrahedra Fill Space?"
>> > author Marjorie Senechal,
>> > Mathematics Magazine, Vol.54, No.5, Nov. 1981
>> > (pp 227-243)
>
> "... Aristotle did not state explicitly that he meant regular
> tetrahedra..."
>
> I do not understand the importance of all-filling space objects (a static
> concept) when space is necessary for anything to grow, move, develop,
> change, etc. People have a strange idea that
space needs to be filled.
It
> goes along with thinking of space as commodity to buy and sell. Where is the
> sense of all this?
Hi Brad --
I'm impressed by your cube necklace. Reminds me of Yoshimoto Cube.
Well done.
As to all-space-filling objects, they're a part of spatial logic and even
nature has lots of frozen static geological forms (many of which are
bought and sold, I can't deny it -- was happening long before I got here).
I've been harping on this Mite (minimum tetrahedron) in the last
few weeks, having held a contest, timed with annual Portland's
Rose Festival, for a Minimum Space-filler.
I was looking for the minimal shape that'd fill space alone, without
mirror images (left and right versions). The Mite was already the
answer I had in mind but maybe some judges would come out of
the woodwork and tip the scales another way? We had some
lengthy debates on another geometry
list.
Having been to a scientific lecture on the naming and categorization
of planets by the Vatican's chief astronomer some years ago, I know
that nomenclature is an important business -- the Vatican takes it
very seriously.
Mathematics, touting itself as a "universal language" is nevertheless
full of nooks and crannies where esoteric nomenclature pertains.
In this tiny subculture that cares about polyhedra, from several
angles, it makes a difference if we call our minimum space-filler
a Mite or not.
Mites make Sytes which make Kites (not the same as the
Penrose kite but there's room for qualified meanings).
Although the LA Times says there's "no magic bullet" for fixing
math education **, I'd like to propose that the Mite is our magic bullet.
I'm only being somewhat tongue in cheek, as I think spatial
geometry should and could be a part of an education Renaissance,
should we decide to
pull ourselves together and plan for the future
more seriously (understood that many have given up on doing
that).
What makes the Mite / Syte / Kite nomenclature attractive is
it comes with a more complete set of polyhedra organized in
a table with many more whole number and/or rational volumes
than are usually conveyed, streamlining the whole subject
immeasurably.
For example, our Mite has volume 1/8 while our rhombic dodeca-
hedron (another space-filler) has volume 6, and our cube
(another space-filler) volume 3 and so on.
The regular tetrahedron, which you alluded to going back a
post, has a volume of unity. That's part of what's innovative
about the Montessori-compatible set of shapes...
From my point of view, we're sitting on a gold mine of
mostly unshared spatial geometric lore, part of our
collective heritage. That's probably a metaphor you
don't like though (gold
mine) as it connotes buying and
selling. I understand your qualms.
** http://articles.latimes.com/2010/may/30/opinion/la-ed-eval-20100530>
> Attached you will find pics of a 1985 model I made to demonstrate one way of
> dividing the cube into a tetrahedra necklace. You might find it interesting.
> This is not an easy puzzle to reassemble, but educational when thinking
> about space-filling.
>
> Brad
Looks to be. Pondering those pictures...
Kirby
>
>
> Bradford Hansen-Smith
> Wholemovement
> 4606 N. Elston #3
> Chicago Il 60630
>
www.wholemovement.com>
> ________________________________
> From: kirby <
kirby...@gmail.com>
> To: MathFuture <
mathf...@googlegroups.com>
> Sent: Fri, June 11, 2010 1:56:33 AM
> Subject: [Math 2.0] Re: Tessellations Again
>
> On Jun 10, 5:56 pm, kirby <
kirby.ur...@gmail.com> wrote:
>> Here's a link to a Math Forum post from earlier today:
>>
>> http://mathforum.org/kb/message.jspa?messageID=7094310&tstart=0>>
>> Note the link to ConceptNet, a cool (and free) MIT
resource.
>>
>> However (a sign of the times?), the assertion about the tetrahedron is
>> false.
>>
>> And I quote:
>>
>>
"""
>>
>> Speaking of our geometry junkyard, check out this
>> screen shot from ConceptNet out of MIT. Do you see
>> the error
(two of them actually):
>>
>>
>> http://www.flickr.com/photos/17157315@N00/4680326861/http://csc.media.mit.edu/docs/conceptnet/overview.html>>
>> """
>
> Here is the screen shot again:
>
> http://controlroom.blogspot.com/2010/06/more-stress-tests.html>
> Re: IsA(tetrahedron, four polygon equal)
>
> Answer key:
>
> Error 1: a tetrahedron is not a polygon
> although it is the only polyhedron comprised
> of just four polygonal facets.
>
> Error 2: these facets need not be equal.
>
> Now maybe this IsA(tetrahedron, four polygon equal) is saying
>
a tetrahedron is comprised of four equal polygons. That'd be
> only half the mistake then ("equal" still too restrictive).
>
> I'd need to see what it says for a Cube -- although in that
> case more than one polyhedron consists
of six equal polygons
> (there's a dipyramid...).
>
> We find very few associations for Tetrahedron in general in
> ConceptNet. No "simplex". Kinda scary, to think this
> might be a mirror of our collective semantic web. Our
> spatial geometry is so weak!
>
> However, in Math 2.0, we could build our own ConceptNets,
> and purposely invest them with lots of associations,
> connotations. The Web is already playing that role at
> some level, but it's fun to use more specialized tools
> sometimes, such as Maria knows about.
>
> My own geometrical subculture has tetrahedra called
> Mite and Sytes (Syte = Mite + Mite), also A, B, T and
> some others (Mite = AAB) -- canonical "blocks" in a
> language game of assemblies and dissections, relative
> volumes. I'm alluding to published literature, not just
> some
ultra-esoteric board game or science fiction.
> Practically no one teaches this stuff though, outside
> of certain math circles. We live as outlaws.
>
> The Cuisenaire rods of Caleb Gattegno fame, far better
> known, likewise give that "right brain" experience (spatial,
> graphical). It's so important to find those bridges, twixt
> lexical and graphical content. Those colored rods are
> far more rectilinear than ours however, and reinforce
> the dominant ideas of "box" and/or "blocks".
>
> I've cast our more tetrahedrally based ethnicity in the
> form of so-called Martian Math (science fiction flavored).
> I've got it linked to some school Web pages here and
> there. For example:
>
> http://worlduniversity.wikia.com/wiki/Mathematics#Select_Wikis>
http://worlduniversity.wikia.com/wiki/Quakers_-_Religious_Society_of_Friends#Select_Wikis>
> Sometimes we make fun of how the mainstream culture
> seems so ignorant of the Tetrahedron, can't bring itself to
> use the word, has to say "three sided pyramid". Even
> NASA does this.
>
> Kirby
>
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