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6 votes
1 answer
278 views

A Sauer-Shelah-like lermma for prefix tree

I proved a variant of the Sauer-Shelah lemma and I was wondering if something like that is already known. Let $S \subseteq \{0,1\}^n $. We say that a set of coordinates $K \subseteq [n]$ is shattered ...
Or Meir's user avatar
  • 419
2 votes
0 answers
87 views

Restricted Erdos-Ko-Rado theorem reference

Consider a family $\mathfrak{F}$ of $k$ element subsets of $\{1,2,..,n\}$, where $n\geq 2k$, such that any two members of $\mathfrak{F}$ have nonempty intersection. The Erdos-Ko-Rado theorem asserts ...
Chris H's user avatar
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1 vote
1 answer
168 views

Number of distinct 3-sets formed as subsets of a 4-uniform set family

Let $\mathcal{F} \subseteq \binom{[n]}{4}$ be a collection of size-4 subsets of $\{1,\ldots,n\}$, i.e., a 4-uniform set family. Let $\mathcal{F'}$ be the collection of size-3 sets for which a ...
Bart Jansen's user avatar
3 votes
0 answers
133 views

Kruskal-Katona for multisets?

Following Fedor Petrov's remarks, here is a "set-theoretic version" of the question I asked a while ago. For integer $n\ge 1$, denote by $\mathcal M_n$ the family of all (finite) multisets with the ...
Seva's user avatar
  • 23k
4 votes
0 answers
114 views

Kruskal-Katona for homocyclic groups?

I need a version of the Kruskal-Katona theorem (better still, of the Lovasz "approximate" version thereof) for the elementary abelian / homocyclic groups, in the following spirit: What is the ...
Seva's user avatar
  • 23k