Summary

  • The pigeonhole principle is a simple mathematical concept that states that if six items are put into five containers, at least two items will end up in the same container.
  • While this may sound like a simpleminded party trick, it has become a non-trivial tool for computer scientists to prove the hidden relationships between different problems in theoretical computer science.
  • The principle can be applied in various everyday situations, such as in attenuated password reuse in a crowded stadium to having the same set of digits being reused in different passwords.
  • Through thought experiments, a computer scientist has extrapolated the simple principle into a whole new avenue of research in complexity theory, where problems that are guaranteed to have solutions because of the pigeonhole principle have been dubbed “APEPP” (abundant polynomial empty-pigeonhole principle) problems.
  • This new class of computational problems has led to new insights into old problems that have been around for over 50 years.
  • The simplicity of the concept has led the computer scientist to quip that “It goes to the bone of important problems in complexity.

By Ben Brubaker

Original Article