# Inversion (in combinatorics)

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Inversion may refer to:

• An inversion of a permutation $\pi$ on the ordered set $\{1,2,\ldots,n\}$ is a pair $i < j$ such that $\pi(i) > \pi(j)$
• A transposition, a permutation that exchanges two elements
• A derangement, a permutation with no fixed points
How to Cite This Entry:
Inversion (in combinatorics). Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Inversion_(in_combinatorics)&oldid=39878