Questions tagged [information-theory]

For puzzles that use an aspect of information theory - the processing and transmission of information.

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Two Sheriffs and Eavesdroppers - 3

“The Two Sheriffs” puzzle was already discussed here. This puzzle has only one difference: we have six suspects instead of eight. Two sheriffs in neighboring towns are on the track of a killer, in a ...
mathlander's user avatar
1 vote
0 answers

What's with the flip?

Uh-oh... We should've taken Professor Kernighan's advice before taking this trip and learned the local language. This desert is dreadful and we just want to reach civilization again, as fast as ...
Hazel へいぜる's user avatar
9 votes
3 answers

Judgment-free construction of a playlist

Alice and Bob are planning a long car trip and need to come up with a playlist for it. For any given song, they have one of four opinions on it: "That's, like, my favorite song ever" (love), ...
Joseph Sible-Reinstate Monica's user avatar
-3 votes
1 answer

Ruins Game - Puzzle Edition

The ruins are clear to you. They're real, and you're trapped by lava. But before you can get the button, there's a puzzle: Send: Receive: Send: Receive: Send: Receive: Find my ...
Someone's user avatar
  • 544
6 votes
1 answer

6 balls and a scale

Suppose you are given 6 balls all of which look identical. You’re told that 4 of the balls all weigh the same, but there are 2 balls that have unequal weights. Additionally, these two ...
user57753's user avatar
18 votes
7 answers

Cracking Nested One-time Pads

Inspired by the famous "how to send a locked box without pre-shared keys" puzzle, I have designed a Truly Clever and Very Secure cryptographic protocol for situations where you must send a secret ...
Bass's user avatar
  • 76k
8 votes
1 answer

IBM Research Puzzle – 5-ops implementation of erasure code

I found this interesting puzzle on IBM Research Puzzling Page called Ponder This; specifically, here. Design a storage system that encodes 24 information bits on 8 disks of 4 bits each, such that: ...
Lifesaving Linen's user avatar
0 votes
2 answers

Transfer of Information between two people [closed]

So if my friend and I both know something that the other wants, how can we transfer this information without any chance of one of us betraying the other and not telling (for example, exchanging notes ...
Tobu's user avatar
  • 21
-3 votes
1 answer

Create a rule, so every integer can be written in only 1 symbol [closed]

Inspired from this question Create a mathematic rule, so every integer can be written in only 1 symbol. Note : white spaces (space, tab, etc) is considered as different symbol
Jamal Senjaya's user avatar
13 votes
4 answers

Rewritable punch cards

Punch cards are boring, primitive, non-rewritable storage devices. Or are they? Indeed, a punch card that is filled to the brim with data seems impossible to write upon. Once you punched a hole ...
BaSzAt's user avatar
  • 5,667
11 votes
5 answers

The oldest wins the prize, but they won't tell their age

I'm trying to design a problem that should be as close as possible to the following setup, while meeting some requirements about its solutions. Initial setup There is a group of more than 2 people ...
Flavian Hautbois's user avatar
12 votes
3 answers

Overhead Projector Cryptography

Back in the day, if you wanted to show an image to a large audience, you would use an overhead projector. This would shine a light through a transparency, which is a clear sheet with a black drawing ...
Mike Earnest's user avatar
  • 32.1k
10 votes
3 answers

Two Sheriffs and Eavesdroppers - 2

“The Two Sheriffs” puzzle was already discussed here Two Sheriffs and Eavesdroppers. This puzzle has only one difference: we have seven suspects instead of eight. Two sheriffs in neighboring towns ...
Alexey Ustinov's user avatar
13 votes
2 answers

A Game of Phones

The Chaos Legion is an infamous criminal organization, responsible for every major disaster in history from the burning of the Library of Alexandria to the recent Sony hack. The Order of Seven is ...
Mike Earnest's user avatar
  • 32.1k
6 votes
2 answers

Snow White and the Secret Message (Secret Sharing Problem)

Snow White needs to send a message to Prince Charming. She considers telling this message to each of the Seven Dwarves, then sending them to deliver it to the Prince. However, the road to the castle ...
Mike Earnest's user avatar
  • 32.1k
34 votes
9 answers

Two Sheriffs and Eavesdroppers

Two sheriffs are working on a case to find one culprit. There were initially 8 suspects; through independent work, each sheriff has narrowed this down to a list of 2. Because they are good sheriffs, ...
Mike Earnest's user avatar
  • 32.1k
11 votes
2 answers

The postmen of Abbab

I've found a very interesting problem that I want to share with you. In the planet Abbab, the alphabet consists only of the letters A and B. All the sentences are written without spaces between words,...
leoll2's user avatar
  • 12.6k