Life is a Test: A Series of Pony Logic Puzzles

by Brony_of_Brody

The Answer 32

Since we're eliminating the more lateral solutions by removing the option to get others involved in this little scheme, including the messy side of the legal system, and we can't threaten the bank manager, the solution is to get this one solved mathematically.

Lyra has the puzzle's solution on-hoof, coloured in three colours (let's say red, blue and yellow). What she needs to do is have ANOTHER copy of the puzzle's solution, in different colours (for example, green, purple and orange). She should then cover up that map and ask Tender Lender to choose two adjacent areas of the map. She then reveals that the two parts are indeed in different colours.

Depending on how skeptical Tender Lender is, Lyra could be there for a while. If the map were made up off one hundred shaded parts as an example, if Lyra actually doesn't have the solution, at least one area of the puzzle will have two areas shaded in the same colour, and thus a 1% chance of being caught out. So after the first reveal, Tender Lender can at least be 1% sure the solution is real.

Lyra should then repeat the above highlighted steps again, changing colours every time (in case Tender Lender has an exceptional memory), including making the copy of the solution and redoing it again. Repeat until Tender Lender is convinced. If Lyra has an incomplete solution, the more this is repeated and she isn't caught, the likelihood of a lie plummets to negligible levels, if it were completed save for one border.

This sort of solution is an example of zero-knowledge proof, for those of you nerdy enough to try and look it up: a way to prove you know a thing without any proof except the fact you know the thing.