---
tag: 0XHWTD3MPV
kind: concept
name: Derangement
msc: [05A05]
sources:
  - url: https://en.wikipedia.org/wiki/Derangement
    locator: lead section
same_as:
  wikidata: Q1207920
  wikipedia: Derangement
---

## Summary

A derangement is a permutation that moves every element. Derangements answer the classical hat-check problem, and their number is a standard application of inclusion and exclusion. The node [[derangement|0TH61JR04G]] gives the precise definition.