[HN Gopher] A two-person method to simulate die rolls
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A two-person method to simulate die rolls
Author : Fraterkes
Score : 32 points
Date : 2025-12-05 19:32 UTC (2 days ago)
(HTM) web link (blog.42yeah.is)
(TXT) w3m dump (blog.42yeah.is)
| AnotherGoodName wrote:
| A + B mod n seems much easier than this.
| BoiledCabbage wrote:
| Yup
| tomsmeding wrote:
| The method proposed is just A - B mod n. The two are entirely
| equivalent.
| AnotherGoodName wrote:
| A few extra steps to essentially manually do the mod part
| tbh. Would take their 20 line program to a 1 liner.
| IanCal wrote:
| This starts by assuming humans are bad at coming up with unbiased
| numbers but then requires them to do so. I don't get how this
| could work with biased inputs.
| jdpage wrote:
| Bear in mind, the terminal goal doesn't actually require
| unbiased numbers; the way most TTRPGs work is that you're
| trying to roll over or under a target number to get a weighted,
| unpredictable outcome. The idea is that while players (usually)
| want any given action to succeed, they some of their actions to
| fail in order to preserve narrative interest, while having
| their character be better at some things than others.
|
| As such, while randomness is _best_ , the given method is quite
| sufficient for having fun, and both players can agree that it's
| fair: they each have equal influence over the result.
| xg15 wrote:
| > _We can prove that in an ideal situation, the die roll will be
| fair. Assuming both parties can come up with unbiased random
| numbers ranging from [0;12)..._
|
| Doesn't that assumption remove the entire problem though? I
| thought the whole reason for the method was that people _can 't_
| easily think of an unbiased random number.
|
| Or put differently, if that's your starting point, what's
| stopping you from simply doing (A mod 6) + 1?
| AnotherGoodName wrote:
| I think the game theory inherit here makes it ok for this
| purpose. You get an advantage being random. You're likely still
| not going to generate random numbers but at least there's good
| motivation to be random and that part just becomes part of the
| game imho (guess what number the opponent calls to maximize
| your roll).
|
| Of course as others note this is a convoluted mod n process.
| torginus wrote:
| Yeah, the only valuable idea here is the angle-one, which is
| like a modulo, making the approach a primitive LCG, which is a
| way of generating pseudorandom numbers from seeds.
|
| I'd say the only unbiased and non crappy method here is to feed
| the 2 participants' numbers into some sorth of hash function.
| zeroonetwothree wrote:
| It would be more interesting to look at how much this reduces
| bias based on numbers humans actually tend to generate.
|
| BTW a "classic" method of generating random numbers is to look at
| the second hand of a watch mod n.
| AlotOfReading wrote:
| Another procedure based on a similar problem I worked on with a
| friend: you both pick positive integers a and b, then add them
| together to create c. Either sqrt(c) or sqrt(c+1) is irrational
| and the fractional digits provide your random numbers. If you
| need a new sequence, you take some digits from the current
| expansion and sqrt() them again.
|
| Might not be unbiased, but good luck proving it.
| amelius wrote:
| After a while both people will get tired or bored and start
| generating the same number over and over again. At which point
| the method breaks down.
| fweimer wrote:
| Usually, commitment schemes are used for this:
| https://en.wikipedia.org/wiki/Commitment_scheme
|
| (However, if the stakes are high enough, the party that learns
| the outcome first can choose to exit the protocol if they are
| unsatisfied with the result.)
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(page generated 2025-12-07 23:00 UTC)