A Discontinuity in the Distribution of Fixed Point Sums
The quantity $f(n,r)$, defined as the number of permutations of the set $[n]=\{1,2,\dots n\}$ whose fixed points sum to $r$, shows a sharp discontinuity in the neighborhood of $r=n$. We explain this discontinuity and study the possible existence of other discontinuities in $f(n,r)$ for permutations. We generalize our results to other families of structures that exhibit the same kind of discontinuities, by studying $f(n,r)$ when "fixed points" is replaced by "components of size 1" in a suitable graph of the structure. Among the objects considered are permutations, all functions and set partitions.
Keyword(s):
2010 ◽
Vol 25
(24)
◽
pp. 4603-4621
◽
Keyword(s):
2005 ◽
Vol 2005
(19)
◽
pp. 3045-3055
◽
Keyword(s):
Keyword(s):
2020 ◽
pp. 241-249
Keyword(s):
2018 ◽
Vol 99
(03)
◽
pp. 497-507
◽