Identifier
- St000702: Permutations ⟶ ℤ
Values
[1,2] => 2
[2,1] => 1
[1,2,3] => 3
[1,3,2] => 2
[2,1,3] => 2
[2,3,1] => 1
[3,1,2] => 2
[3,2,1] => 2
[1,2,3,4] => 4
[1,2,4,3] => 3
[1,3,2,4] => 3
[1,3,4,2] => 2
[1,4,2,3] => 3
[1,4,3,2] => 3
[2,1,3,4] => 3
[2,1,4,3] => 2
[2,3,1,4] => 2
[2,3,4,1] => 1
[2,4,1,3] => 2
[2,4,3,1] => 2
[3,1,2,4] => 3
[3,1,4,2] => 2
[3,2,1,4] => 3
[3,2,4,1] => 2
[3,4,1,2] => 2
[3,4,2,1] => 2
[4,1,2,3] => 3
[4,1,3,2] => 3
[4,2,1,3] => 3
[4,2,3,1] => 3
[4,3,1,2] => 2
[4,3,2,1] => 2
[1,2,3,4,5] => 5
[1,2,3,5,4] => 4
[1,2,4,3,5] => 4
[1,2,4,5,3] => 3
[1,2,5,3,4] => 4
[1,2,5,4,3] => 4
[1,3,2,4,5] => 4
[1,3,2,5,4] => 3
[1,3,4,2,5] => 3
[1,3,4,5,2] => 2
[1,3,5,2,4] => 3
[1,3,5,4,2] => 3
[1,4,2,3,5] => 4
[1,4,2,5,3] => 3
[1,4,3,2,5] => 4
[1,4,3,5,2] => 3
[1,4,5,2,3] => 3
[1,4,5,3,2] => 3
[1,5,2,3,4] => 4
[1,5,2,4,3] => 4
[1,5,3,2,4] => 4
[1,5,3,4,2] => 4
[1,5,4,2,3] => 3
[1,5,4,3,2] => 3
[2,1,3,4,5] => 4
[2,1,3,5,4] => 3
[2,1,4,3,5] => 3
[2,1,4,5,3] => 2
[2,1,5,3,4] => 3
[2,1,5,4,3] => 3
[2,3,1,4,5] => 3
[2,3,1,5,4] => 2
[2,3,4,1,5] => 2
[2,3,4,5,1] => 1
[2,3,5,1,4] => 2
[2,3,5,4,1] => 2
[2,4,1,3,5] => 3
[2,4,1,5,3] => 2
[2,4,3,1,5] => 3
[2,4,3,5,1] => 2
[2,4,5,1,3] => 2
[2,4,5,3,1] => 2
[2,5,1,3,4] => 3
[2,5,1,4,3] => 3
[2,5,3,1,4] => 3
[2,5,3,4,1] => 3
[2,5,4,1,3] => 2
[2,5,4,3,1] => 2
[3,1,2,4,5] => 4
[3,1,2,5,4] => 3
[3,1,4,2,5] => 3
[3,1,4,5,2] => 2
[3,1,5,2,4] => 3
[3,1,5,4,2] => 3
[3,2,1,4,5] => 4
[3,2,1,5,4] => 3
[3,2,4,1,5] => 3
[3,2,4,5,1] => 2
[3,2,5,1,4] => 3
[3,2,5,4,1] => 3
[3,4,1,2,5] => 3
[3,4,1,5,2] => 2
[3,4,2,1,5] => 3
[3,4,2,5,1] => 2
[3,4,5,1,2] => 2
[3,4,5,2,1] => 2
[3,5,1,2,4] => 3
[3,5,1,4,2] => 3
[3,5,2,1,4] => 3
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Description
The number of weak deficiencies of a permutation.
This is defined as
$$\operatorname{wdec}(\sigma)=\#\{i:\sigma(i) \leq i\}.$$
The number of weak exceedances is St000213The number of weak exceedances (also weak excedences) of a permutation., the number of deficiencies is St000703The number of deficiencies of a permutation..
This is defined as
$$\operatorname{wdec}(\sigma)=\#\{i:\sigma(i) \leq i\}.$$
The number of weak exceedances is St000213The number of weak exceedances (also weak excedences) of a permutation., the number of deficiencies is St000703The number of deficiencies of a permutation..
References
[1] Elizalde, S. Statistics on pattern-avoiding permutations MathSciNet:2717168
[2] Burstein, A., Eriksen, N. Combinatorial properties of permutation tableaux MathSciNet:2732829
[2] Burstein, A., Eriksen, N. Combinatorial properties of permutation tableaux MathSciNet:2732829
Code
def statistic(pi):
return sum(1 for i,pii in enumerate(pi) if pii <= i+1)
Created
Mar 03, 2017 at 10:16 by Christian Stump
Updated
Mar 22, 2017 at 13:18 by Martin Rubey
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