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The cursed d65536

aleph.se

51–60 of 74 posts

Re: The cursed d65536

#51
post #47
post #46

Earlier quoted context omitted.

No.

Why? Is it because it haven't been found, or is there a proof of impossibility?

It would require P=NP (widely assumed to be false) and the nonexistence of one-way functions (actually an even stronger assumption). Any one-way function can be used as a PRNG, and it's computationally infeasible to distinguish that from a true random number generator, almost by definition.

Re: The cursed d65536

#52
post #20

Probably says something about me that my immediate reaction to the number 65536 wasn’t 2^16, but rather the frequency of the timer crystal you had to swap into a Radio Shack tone dialer to make a “red box”[1] that would let you make free phone calls on US pay phones by simulating the analog coin code sound of a quarter being deposited. Fun fact that the “red box” was the first hackaday article[2] posted way back in 2…

Interesting, most timer crystals I'm familiar with are 32768 hz.

Re: The cursed d65536

#53

There's an assumption here that a polytope with equal area faces will be fair. I'd like to see a proof. My mathematical intuition is that the probability of stopping on a face depends on the extent that nearby faces slow a rotation, which depends on the angle of attack across each face. Without symmetry, this will vary by face.

The article explicitly says that equal areas are not required for fairness; and gives this explanation for wanting equal areas: "Dice that are fair by symmetry (and hence under any reasonable throwing dynamics) always have to have an even number of sides and belong to certain symmetry groups (Diaconis & Keller 1989)."

Re: The cursed d65536

#54
post #47
post #46

Earlier quoted context omitted.

No.

Why? Is it because it haven't been found, or is there a proof of impossibility?

Assuming "random" means that there is no program to generate the sequence that is shorter than the sequence itself, proving the nonexistence of such a program is equivalent to the halting problem. See https://en.wikipedia.org/wiki/Kolmogorov_complexity

Re: The cursed d65536

#55
post #11
post #5

From the broken first attempt: Each face has 3 vertices, shared between 6 faces, so the total number of vertices is 65536, and they become faces of my die. This should have tipped you off. If you have six triangular faces around every vertex, you have a flat Euclidean plane, not a sphere with positive curvature. For another example of this: https://m.youtube.com/watch?v=jfSTwqmrQDc

That's why "don't do math after midnight". But I don't get what's wrong with repeated throws of tetrahedron - 2 bits of result at a time - or even icosahedron, with re-throws if one of 4 "wrong" sides is up - 4 bits at a "good" throw...

You can also make repeated throws of an octahedron for 3 bits per throw. 16 is not a multiple of 3, but there's no difficulty with just discarding the 17th and 18th bits. So you'd need to roll 6d8 instead of 8d4.

Re: The cursed d65536

#56
post #50
post #44

Look at the humble d10 for inspiration. The trick is to avoid making a spherical-looking die. A fair d65536 could look like a pair of cones glued together, with 32768 sides per cone. Alternatively, one can make a fair 65536-sided cylinder with rounded ends.

In practice though I'd go with four of those: https://commons.wikimedia.org/wiki/File:D16_HEX_dice.JPG (assuming that I can get them in four different colors)

Blasphemy. Single fair die or bust.

Re: The cursed d65536

#57

> This is of course hilariously cursed. It will look almost perfect, but very rarely give numbers outside the expected range. If the D65538 is fair, it is usable: you just discard the two unwanted values when they show up and roll again. Those faces could be labelled as "roll again". If you have a uniform source of random numbers from 1 to N, you can get a uniform distribution from 1 to M < N simply by discarding val…

Rejection sampling , that is. Unexpectedly, but obviously in retrospect, the common (ancient) wisdom of using that in the continuous case instead of figuring out tricky combinations of special functions to get the result from a bounded number of uniform samples... fails miserably on LuaJIT. Of course atan2() is not the fastest thing in the world, but on a compiler that only really understands loops with linear bodies…

[deleted]

Re: The cursed d65536

#58
post #2

I know it's not the point of TFA, but you can just roll a d8 6 times, generating 3 bits each time, for a total of 18 bits, and then discard two of them.

You can buy hexadecimal dice ie D16 with the sides labelled 0 through F, I have some, I use them to generate random numbers when it is important to me that I personally have confidence these are random numbers. With hex dice you can generate 16 bits with four rolls, four bits each time. Obviously you're more likely to already have a D6 somewhere, but then you're even more likely to own a coin, and 16 coin tosses is a…

> Obviously you're more likely to already have a D6 somewhere, but then you're even more likely to own a coin

I'm not sure this is still true. At least not here in Sweden. Everyone I know owns multiple board games which come with at least one D6 and in recent years I've had discussions with friends and family about us paying everything electronically nowadays. There has even been talk about the risk to our society of no one having cash anymore.

In fact, some weeks ago I needed a coin to show my kids when they asked about this physical money they'd heard of and I couldn't find one.

Re: The cursed d65536

#59
I believe that there are fewer than factorial(65536) particles in our universe[0], so I reject using a die with that many faces to equalize the probabilities. As other comments point out, a mere 65536 faces is on the verge of practicality.

[0]https://www.popularmechanics.com/space/a27259/how-many-parti...

Re: The cursed d65536

#60
post #20

Probably says something about me that my immediate reaction to the number 65536 wasn’t 2^16, but rather the frequency of the timer crystal you had to swap into a Radio Shack tone dialer to make a “red box”[1] that would let you make free phone calls on US pay phones by simulating the analog coin code sound of a quarter being deposited. Fun fact that the “red box” was the first hackaday article[2] posted way back in 2…

I guess it says you're more into hardware than you're into math, when I saw the title I thought 'this must be some really weird Dungeons and Dragons article'
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