DerangementYou are currentlybrowsing as guest. Click here to log in 

A Derangement is a permutation that leaves nothing in its "natural" place. Alternatively, it's a function f from {1,...,n} to {1,...,n} such that f(i) is never i.
The number of derangements of n items is given by

In particular, in any arrangement we can choose a selection of items to derange, then derange them, leaving the others unmoved. Hence:
As n gets larger the probability that a randomly chosen permutation is a derangement approaches
Last change to this page Full Page history Links to this page 
Edit this page (with sufficient authority) Change password 
Recent changes All pages Search 