Is a Circle One-Dimensional or Two-Dimensional?
A recent question led me to find a series of old questions, each answering it at a different level. All of them are worth presenting.
Month: September 2025
Pigeonhole Principle II: Sets, Subsets, and Sums
Last time, we looked at the Pigeonhole Principle, applying it to geometrical problems, largely about distances, gradually working from almost literal “balls and boxes” (“pigeons and pigeonholes”) to more abstract applications that are harder to see. Here, we will go beyond that, proving facts about sets.