Eight by eight matrix, flip a coin.
Moderators: jestingrabbit, Moderators General, Prelates

 Posts: 2
 Joined: Fri Dec 25, 2015 8:13 am UTC
Eight by eight matrix, flip a coin.
Say we have an eight by eight matrix, and each entry has a coin, heads or tails, determined by Randall Monroe. Randall Monroe points at a coin he deems "worthy." Then, we must flip exactly 1 coin. A partner with whom I have conspired with before must be able to tell which coin is "worthy." Is this possible or not?
 emlightened
 Posts: 42
 Joined: Sat Sep 26, 2015 9:35 pm UTC
 Location: Somewhere cosy.
Re: Eight by eight matrix, flip a coin.
So there's an 8x8 matrix of values, heads or tails, and you can look at the entire matrix before Randall selects a coin and flips it over. Can't you just memorise the entire matrix, tell it to your partner, and leave them to determine which coin was flipped? If not, then they can't know any prior knowledge about the matrix, just what methods could be used. None, as it happens, as if this isn't a lateral thinking problem, you're partner's just looking at a 8x8 array of coins, with no idea which to turn.
For instance, all of the coins could be heads, except for the one Randall deems worthy, which is then also flipped to be heads. your partner now has to pick the worthy coin from 64 heads, with nothing to distinguish between them. Either it's impossible, a memory task, requires lateral thinking, or I've misunderstood the problem.
For instance, all of the coins could be heads, except for the one Randall deems worthy, which is then also flipped to be heads. your partner now has to pick the worthy coin from 64 heads, with nothing to distinguish between them. Either it's impossible, a memory task, requires lateral thinking, or I've misunderstood the problem.
██████████████████████████████████████████████████████████████████████████████████████████████████████
"Therefore it is in the interests not only of public safety but also public sanity if the buttered toast on cats idea is scrapped, to be replaced by a monorail powered by cats smeared with chicken tikka masala floating above a rail made from white shag pile carpet."
"Therefore it is in the interests not only of public safety but also public sanity if the buttered toast on cats idea is scrapped, to be replaced by a monorail powered by cats smeared with chicken tikka masala floating above a rail made from white shag pile carpet."

 Posts: 35
 Joined: Wed Sep 24, 2014 5:01 pm UTC
Re: Eight by eight matrix, flip a coin.
Randall sets the initial array of heads and tails and selects a coin, then based on that choice, you select any coin (not necessarily the same one) and flip it over, then the partner (who has not looked at the initial array of coins, and has not communicated with you since you were first able to see it) gets to look at the array as it exists after you flipped a coin over. From that information, the partner has to determine which coin is the one Randall chose.
Spoiler:
Who is online
Users browsing this forum: No registered users and 8 guests