Knights and Knaves

Knights and Knaves

One always lies, and one always tells fiddly old truths.

A handful of variations on the classic puzzle. Outwit liars, avoid lions, talk to statues, and roll the dice with clowns!

(Note for mobile players: this looks best in landscape mode)

How to play

Select a guard to begin building a question, then use the popup keyboard as well as the other doors, guards, and speech bubbles to add symbols to your question.

Questions can range from as simple as:

🚪1 ?

 to as complicated as (not a real solution):

⬤ = 💬1(🙂2 & ▲) / (🚪3 ≠ 🎲) ?

Once you have reached each level's question limit, choose a door to enter. If you chose wrong, you can try again - and even get a hint if you want one.

You can also hit the Questions button in the top right to view your entire conversation, as well as examine a logic table showing various possible responses to your last question.

Also, don't worry if you choose wrong and lose a balloon - they're not worth anything more than bragging points! And you can always refresh this page to restart the game from scratch.

Custom puzzles

The format for custom levels goes like this:

numLiars:numDoors:numQuestions:guardType-useLanguage-isStatue:doorType

Guards can be "guard", "vendor", "monty", "monkey", or "clown", and doors can be "gate", "door", "hedge", or "mirror".

An example level:

1:2:1:guard-false-false,guard-false-false:gate

Credits

• Raymond Smullyan, who popularized the puzzle and coined the phrase
  
• Edsger Dijkstra's shunting yard algorithm, which I made a mess of
• BR Heap's permutation algorithm, which I left alone
• Monty Hall and his problems
• JQuery
• Fonts (Calistoga and Quicksand) by Google Fonts

Soundtrack