
How to Slice a Bagel into Two Linked Halves - msvan
http://www.georgehart.com/bagel/bagel.html
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huhtenberg
Neat, but academic, because as everyone undoubtedly knows slicing bagel into a
Mobius strip is _far_ more practical. Not only does it give you a surface for
jam-and-buttering, but also keeps the construct in a single piece ensuring an
unbeatable simplicity and predictability of the user experience. It's the same
technique as in the article, but the knife needs to rotate at the half of its
angular speed as it goes along bagel's diameter.

~~~
Bill_Dimm
_Not only does it give you a surface for jam-and-buttering..._

Yeah, but if you drop it on the floor it is guaranteed to land jam-side-down
100% of the time.

~~~
Coincoin
It will fall jam side down 100% of the time even if it's not a Mobius strip.
It's the law.

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up_and_up
> It is much more fun to put cream cheese on these bagels than on an ordinary
> bagel. In additional to the intellectual stimulation, you get more cream
> cheese, because there is slightly more surface area.

I believe this is winning on all fronts here.

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joshu
trivia: vi hart is child of george hart. i guess awesome runs in that family.

~~~
GuiA
And Erik Demaine is the son of the prodigal Martin Demaine. It seems that some
mathematicians are good at communicating their passion to their children.

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emillon
This construction shows Villarceau circles[1], which are the nontrivial circle
sections of a torus. This can be also seen on the POV raytracer hall of
fame[2].

    
    
        [1]: http://en.wikipedia.org/wiki/Villarceau_circles
        [2]: http://hof.povray.org/Villarceau_Circles-CSG.html

~~~
philsnow
Oh man, if ever I lose my wedding ring, I know what I'm going to commission to
replace it.

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yen223
And they say topology is useless!

~~~
kzrdude
We expanded the utilty from teacups and donuts to now include bagels!

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mauvehaus
I have a number of friends who are middle and high school math teachers. I
have asked them to demonstrate this for their students and report back on how
utterly blown their students' minds are.

Stuff like this makes me wish I had continued on the path of becoming a math
teacher myself rather than returning to the world of software.

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a_p
The rest of George Hart's site is interesting as well, especially his
encyclopedia of virtual polyhedra [1]. There is also a part 2 of
"Mathematically Correct Breakfast" (this time a trefoil knot) [2], and his
sculptures are worth looking at as well [3].

[1] <http://www.georgehart.com/virtual-polyhedra/vp.html>

[2] <http://www.georgehart.com/bagel/knot.html>

[3] <http://www.georgehart.com/sculpture/sculpture.html>

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ambiate
Previous discussions:

<http://news.ycombinator.com/item?id=982249>
<http://news.ycombinator.com/item?id=1234503>
<http://news.ycombinator.com/item?id=1967930>

This story has allotted a total of 656 karma, interesting.

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crusso
I felt a great disturbance in the Force, as if millions of bagels suddenly
cried out in terror, and were suddenly silenced.

~~~
JadeNB
> … and were suddenly silenced.

You misspelt 'sliced'.

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ck2
Now if they could bake them like this, I could see that fad taking off...

~~~
gojomo
I suspect you could bake two interlocked bagel rings with a little help from a
baking sheet that had angled U-shaped cutouts. You'd mold the rings while the
dough was soft, and the baking sheet would help support the rings, as separate
but interlocked, during baking. (To me, this feels like less of a challenge
than the cutting trick.)

~~~
Samuel_Michon
That won’t work, as the dough isn’t soft enough before it is baked. By that
time, the dough has been shaped, risen for 36 hours and boiled. Baking is a
pretty minor step in the process.

<http://www.genuineideas.com/ArticlesIndex/bagels.html>

~~~
gojomo
Thanks for the reference... seems the proper accessory would need to be
something that helps hold the two in the proper position through
rising/boiling. Maybe something in high-temperature silicone? (And yes, it'd
certainly force a different hole-to-ring proportion...) Needs experiments!

~~~
Samuel_Michon
Sure, that could work. I think it comes down to the definition of a bagel.
Most bagels you can buy in the store don't meet my definition, that's
partially why this exercise is so challenging for me. I will definitely try to
find a solution, though. The idea appeals to me.

—Ashkenazi Jew, my grandmother taught me how to make bagels. It's quite a
process, when done properly.

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sunnybunny
Been waiting for somebody to explain how that could be possible.

~~~
Retric
Normally you take a knife slice a bagel down the middle and you end up with 2
half's but part of that action ends up cutting both sides of the hole at the
same time.

Instead take a knife cut to the center but not the other side then as you cut
around the edge rotate the cut so by the time your around the full bagel the
knife is upside down. If you picture it at one point knife handle is on the
above the bagel and after a little while it's below the bagel. The only trick
is to make you cut line up when your done.

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doktrin
Great. Now I have the urge to dissect bagels at 2 AM :)

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Evbn
I have tried these cuts a dozen times, never with success. What kind of
knife/dough do you need to make clean cuts? 10 year olds can do it in two
tries, why can't I?

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lessnonymous
Missed the Hacker News on this one ..

I know I'm not heavily karma'd and so my opinion counts for less, but this
isn't the sort of thing I'm expecting on HN. This belongs over in Reddit
(where I promise I'll still see it .. probably reposted a dozen times)

~~~
scott_s
"Please don't submit comments complaining that a submission is inappropriate
for the site." <http://ycombinator.com/newsguidelines.html>

Complaining is just noise.

~~~
lessnonymous
Thanks for pointing me to those.

I also missed this one: > If your account is less than a year old, please
don't submit comments saying that HN is turning into Reddit. (It's a common
semi-noob illusion.)

I'm only up to 326 days, so I'll go back to my corner and apologize
(genuinely) for not being aware of these rules.

Though I still don't think it belongs here ;-D

