The set of ratios of derangements to permutations in digraphs is dense in \([0,1/2]\)
The electronic journal of combinatorics, Tome 29 (2022) no. 1
A permutation in a digraph $G=(V, E)$ is a bijection $f:V \rightarrow V$ such that for all $v \in V$ we either have that $f$ fixes $v$ or $(v, f(v)) \in E$. A derangement in $G$ is a permutation that does not fix any vertex. Bucic, Devlin, Hendon, Horne and Lund proved that in any digraph, the ratio of derangements to permutations is at most $1/2$. Answering a question posed by Bucic, Devlin, Hendon, Horne and Lund, we show that the set of possible ratios of derangements to permutations in digraphs is dense in the interval $[0, 1/2]$.
DOI :
10.37236/10293
Classification :
05C20, 05C30, 05A05
Mots-clés : ratios of derangements, number of permutations
Mots-clés : ratios of derangements, number of permutations
@article{10_37236_10293,
author = {Bethany Austhof and Patrick Bennett and Nick Christo},
title = {The set of ratios of derangements to permutations in digraphs is dense in \([0,1/2]\)},
journal = {The electronic journal of combinatorics},
year = {2022},
volume = {29},
number = {1},
doi = {10.37236/10293},
zbl = {1481.05061},
url = {http://geodesic.mathdoc.fr/articles/10.37236/10293/}
}
TY - JOUR AU - Bethany Austhof AU - Patrick Bennett AU - Nick Christo TI - The set of ratios of derangements to permutations in digraphs is dense in \([0,1/2]\) JO - The electronic journal of combinatorics PY - 2022 VL - 29 IS - 1 UR - http://geodesic.mathdoc.fr/articles/10.37236/10293/ DO - 10.37236/10293 ID - 10_37236_10293 ER -
%0 Journal Article %A Bethany Austhof %A Patrick Bennett %A Nick Christo %T The set of ratios of derangements to permutations in digraphs is dense in \([0,1/2]\) %J The electronic journal of combinatorics %D 2022 %V 29 %N 1 %U http://geodesic.mathdoc.fr/articles/10.37236/10293/ %R 10.37236/10293 %F 10_37236_10293
Bethany Austhof; Patrick Bennett; Nick Christo. The set of ratios of derangements to permutations in digraphs is dense in \([0,1/2]\). The electronic journal of combinatorics, Tome 29 (2022) no. 1. doi: 10.37236/10293
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