# Questions tagged [information-theory]

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

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### 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 ...
2k views

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 ...
869 views

### 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: ...
167 views

### 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 ...
180 views

### 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
1k views

### 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 ...
427 views

### 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 ...
1k views

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 ...
596 views

### 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 ...
2k views

### 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 ...
628 views

### 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 ...