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Tagged with bell-numbers binomial-coefficients
3
questions
2
votes
0
answers
118
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Number of preorder relations on a set related to the open problem about preorder relations
Consider a set $A=\left\{1,2,3\right\}$,I want to count the number of preorder relations on this set, so there is two cases two consider,either the relation is symmetric or it is not, if the relation ...
user715522
2
votes
1
answer
110
views
New wrong recurrence formula for Bell numbers
Bell numbers are the numbers counting the total partitions on a set with $n$ distinct elements.
Explanation:
Consider a set like $A:=\left\{x_{1},x_{2},...,x_{n}\right\}$
A partial equivalence ...
user715522
0
votes
1
answer
154
views
Probability of set partition
Let $A = \{1\dots n\}$. Do partition of set $A$ on pairwise disjoint two- and three-element subsets randomly. For each n determine probability that number of two-element subsets is equal to three-...
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