Group Theory in the Bedroom: the curious mathematics of mattress flipping | Hacker News Reader

Group Theory in the Bedroom: the curious mathematics of mattress flipping

americanscientist.org

38 pointstokenadult12 comments

A King-sized mattress could be made square by being just 4 inches wider. Not only would it make more rotations possible (8) but it would also be easier to put the sheets on, as it's impossible to put them on the "wrong" way.

Sorry, just a pet peeve of mine.

I would be reluctant to rotate the mattress so that the old feet location is the new head location.

Why? (Ignoring say foot fungus, is it just squeamishness or is there something else I should know? ;))

That would also allow for a more even wear across the mattress. The center (from left to right) of our current mattress becomes soft and saggy over time, which can not be solved by anything but a quarter turn (or a new mattress).

We have tried to rotate the duvet and pillows to get the same effect, only to find The Boy's head at my feet next morning.

If you really want to rotate your mattress: IKEA used to sell round beds and mattresses. It's a bit too "Playboy Mansion" for my taste though, and it severely limits your options in sheets and duvet covers.

I've been peevish about that too. 4" off-square makes no sense.

Solved it by getting a Cal-king. Much happier, more snuggling with my wife, and my toes don't hold up the end of the blankets any more (I'm 6'2").

The only problem I've had since is that 4 Cal-king sheets we ordered in a row were mislabeled, and in fact Kings (or some other shape/size. trust me, they've been pretty weird). But that could be because I'm in the Midwest, where Cal-anything is mostly unheard of.

To get back on topic, the article is rather amusingly complete... I'm quite impressed someone would put this much work into this (though not surprised. A (math) geek, obsessed? never!).

That's quite an amusing extrapolation.

(Kinda O/T) I amused my girlfriend the other day by taking a permanent marker to our mattress. On one side, I wrote "top to bottom" in the top-left and bottom-right corners, facing the edges. On the other side, I wrote "side to side".

Each time you flip, you just look at the bottom corner and it tells you what to do next.

Why not label the configurations 1, 2, 3 and 4? Less writing and you don't need to remember which instruction to read.

That'd work, the only catch being that when you see 1 you need to know where 2 is, and it's on the other side of the mattress (I have a latex mattress, it weighs about 30kg so it's a pain to turn over, even to look. Turning it twice because you got it wrong with the first movement is a big cost.)

You don't actually need to remember which instruction to read, cos they're the same on the each side of the mattress. I could have just written "side to side" on one side and "top to bottom" on the other side, it'd just sometimes be upside down.

Perhaps instead of replacing our crappy mattress with a new one I can instead regale the lovely wife with group theory: "Look, honey. It's our old friend Z2xZ2xZ2."

Won't she be pleased!

If you don't want to browse through 7 pages, here's the full text:

http://www.americanscientist.org/issues/id.3465,y.0,no.,cont...

A much better reading format, thanks for the link!

I haven't had a mattress that's symmetrical along all axis. I only ever 'turn' the mattress 180° parallel to the ground.

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