Logic Puzzles

Read these first

1. 01Deducing From What Other People Do Not Know

   Sometimes the most useful sentence in a puzzle isn't a stated fact, it's someone announcing they *can't* figure something out. That single admission of ignorance rules out entire branches of possibility for everyone listening.

2. 02Pigeonhole Arguments

   If you stuff more pigeons than pigeonholes, some hole gets at least two, an observation so obvious it feels useless, until it's the entire proof that a solution must exist, with no construction required.

3. 03Twelve Coins, One Fake, Three Weighings

   One of twelve coins is fake, lighter or heavier, you don't know which, and a balance scale gives you exactly three weighings to find it and say which way it's off. The trick is designing weighings whose outcomes are informative even when they balance.

Then the rest

1. 04Cheryl's Birthday and Iterated Knowledge
2. 05One Question, Two Guards, One Door
3. 06Adaptive Versus Pre-Committed Weighing Strategies
4. 07Encoding Information With Parity in Hat Puzzles
5. 08Finding the Odd Ball Without Knowing If It Is Heavy or Light
6. 09Mastermind: Deduction From Feedback
7. 10Prisoners in a Line Guessing Hat Colours
8. 11Solving Logic-Grid Puzzles Systematically
9. 12The Chessboard Coin-Flip Prisoner Puzzle
10. 13The Muddy Children Puzzle
11. 14The Poisoned Wine Bottles and Binary Encoding
12. 15The Sum-and-Product Puzzle
13. 16Twenty Questions and the Entropy Bound